16 Medical Mycology (48)

Question 1

With what pathogen is this patient most likely infected?

1 Toxoplasma gondii
2 Cryptosporidium
3 Pneumocystis carinii
4 Mycobacterium
5 Coccidiomycosis

Answer 1

Pneumocystis carinii

Pneumocystis carinii pneumonia (PCP) is one of the leading causes of death in AIDS patients. The immunocompromised status in AIDS results in opportunistic infections like PCP. The patient presents with dry cough and shortness of breath. Chest X-ray shows diffuse bilateral infiltrates extending from the perihilar region. About 90% of HIV-infected patients with PCP have an elevated LDH. Bronchoalveolar lavage may also prove useful in diagnosis.
Other organs may also be affected; hepatomegaly, cotton wool spots, thyromegaly, skin lesions, and bone marrow necrosis have been reported. Treatment is effected with trimethoprim and sulfamethoxazole (TMP-SMX). Pentamidine is used in cases with TMP-SMX toxicity; however, relapses are common.
Toxoplasma gondii is an intracellular parasite with predominant nervous system manifestations. Patients usually present with convulsions, disorientation, and dementia.
Cryptosporidium is a diarrhea-causing protozoan in HIV-infected patients. Patients present with 20 to 40 episodes of watery stools per day and abdominal cramps.
HIV patients are most commonly affected with an atypical form of mycobacterium called Mycobacterium avium intracellulare. It causes tuberculosis-like disease in the lungs, which is usually resistant to treatment.
Coccidioidomycosis causes systemic mycosis involving the brain, liver, bones, skin, and lymphatic tissue. This systemic infection carries a high mortality.

Question 2

What fungi is the most likely causative agent of this patient’s illness?

1 Aspergillus fumigatus
2 Histoplasma capsulatum
3 Penicillium marneffei
4 Cryptococcus neoformans
5 Coccidioides immitis

Answer 2

Histoplasma capsulatum

The patient’s condition is most likely to be acute pulmonary histoplasmosis acquired by exposure to bat guano (excrement) containing spores of Histoplasma capsulatum. In the U.S., infections by H.capsulatum are highly endemic in the Ohio and Mississippi valleys and also in localized foci in mideastern states. Infection occurs due to inhalation of aerosols containing the fungal conidia (spores). Person to person transmission does not occur. Excreta of birds and bats are known to accelerate the growth of the mycelial forms and sporulation of the fungus. Bat guano can be a good source of the spores, as the fungus can colonize in the gastrointestinal tract of bats.
Exposure may result in asymptomatic infection or symptomatic disease. The extent of disease depends on the number of conidia inhaled and the host’s cellular immunity. Pulmonary infection is the primary manifestation of infection. It is often self-limited, with flu-like symptoms from which recovery occurs without any specific treatment. Inhalation of a large number of spores may result in severe pulmonary disease with acute respiratory distress syndrome.
Thermally dimorphic fungi are fungi that occur in 2 morphological forms at different temperatures. Yeast forms are seen in tissues and when grown on enriched media at 37°C. Mycelial forms are seen in the soil and when grown on Sabouraud’s or similar media at 25-30°C. Description of the tissue form given in the question is typical of H.capsulatum.
Histoplasmosis is worldwide in distribution. It is more prevalent in North and Central America. Occupation and travel-associated outbreaks of acute histoplasmosis have been reported in the U.S. Other than acute pulmonary infection, main clinical manifestations of the disease are chronic cavitary pulmonary histoplasmosis and disseminated histoplasmosis.
Chronic cavitary pulmonary histoplasmosis simulates pulmonary tuberculosis and develops in people with pre-existing pulmonary conditions like emphysema or chronic obstructive pulmonary disease (COPD).
Disseminated histoplasmosis occurs in people with impaired cell-mediated immunity, as in HIV-positive individuals, immunosuppressed individuals, and the elderly. Dissemination affects the reticuloendothelial system and may involve other organs including skin and mucous membranes. Rheumatologic syndromes occur as sequelae in some patients with acute pulmonary histoplasmosis.
Laboratory diagnosis of histoplasmosis is done by tests based on microscopy, culture, antigen detection, and serology. Sensitivity and utility of the tests vary with the clinical syndromes, the fungal burden, and host factors.
Serology is reported to have good sensitivity in diagnosing acute pulmonary histoplasmosis. Complement fixation (CF) and immunodiffusion (ID) tests are used to detect antibodies to H and M antigens, which are important exoantigens of H.capsulatum and primary immunoreactive constituents of histoplasmin (HMIN). Immunodiffusion is more specific than CF test and is simpler to perform. A Western blot test for detecting antibodies using deglycosylated M antigen has been reported to be highly sensitive and specific and is useful for diagnosing even early infections. An enzyme-linked immunosorbant assay (ELISA) using purified and deglycosylated HMIN has been found to be rapid, sensitive and specific, and valuable where laboratory facilities are limited.
Urinary antigen detection by Enzyme Immuno Assay (EIA) is useful for diagnosis of acute histoplasmosis. Antigen detection in urine and serum is also very useful in diagnosing disseminated disease. The test has the advantage of a rapid turnaround time and helps to monitor patient’s response to therapy.
Antigen detection assays done with bronchioalveolar lavage (BAL) and histopathological examination of lung biopsy specimens for the yeast forms of H.capsulatum have been helpful for the diagnosis of severe and extensive forms of acute pulmonary infections.
Culture is the gold standard for diagnosis of histoplasmosis, but it is not of much use in diagnosing acute pulmonary infections. In severe acute pulmonary infections following heavy inoculum exposure, culture of lung biopsy and BAL samples have been found helpful. Culture has good sensitivity in chronic pulmonary and disseminated histoplasmosis and is found positive in about 85% of such cases. The method is time-consuming and may take up to 6 weeks. The growth of the fungus on Sabouraud’s agar kept at 25-30°C appears as cottony mycelial growth with characteristic tuberculate macroconidia and small microconidia. On enriched media like blood agar incubated at 37°C, it produces smooth colonies of yeast cells.
Microscopic demonstration of intracellular yeast forms of H.capsulatum in smears of bone marrow or blood helps diagnosis of disseminated histoplasmosis. Giemsa or Wright stain can be used for staining the smears. Fungal stains like Gomori’s methenamine silver (GMS) are used for demonstration of the fungus in tissue sections.
Polymerase chain reaction (PCR) based assays developed for identification of mycelial and tissue forms of H.capsulatum and detection of the fungus in clinical specimens have given promising results. These are not available for routine use.
All other fungi listed can produce pulmonary manifestations but can be excluded due to following reasons.
Aspergillus fumigatus is a mold and Cryptococcus neoformans is yeast. Both are not dimorphic fungi.
Coccidioides immitis is one of the thermally dimorphic fungi and causes coccidioidomycosis, endemic in the dry arid regions of Southwest U.S. The tissue form of the fungus does not resemble that of H.capsulatum and occurs as large spherules (10-80 microns) with a thick doubly refractile wall containing endospores.
Penicillium marneffei is the only Penicillium species shown to possess dimorphism. It produces infections in AIDS patients, and the infection is reported to be endemic only in South East Asia. The yeast form shows a single distinct central septum, which is a distinguishing feature.

Question 3

What is the most likely isolated organism?

1 Histoplasma capsulatum
2 Cryptococcus neoformans
3 Candida albicans
4 Trichosporon asahii
5 Candida glabrata

Answer 3

Cryptococcus neoformans

The diagnosis in the above patient on prolonged steroid therapy is probably meningitis caused by Cryptococcus neoformans. Cryptococcus neoformans is a yeast with a large polysaccharide capsule and is associated with infections, mostly in immunocompromised individuals. Features of the organism mentioned in the question are characteristic of C.neoformans.
Cryptococcus neoformans is a soil saprophyte; it occurs worldwide and feces of birds, like pigeons, are a good source of C.neoformans.
Pathogenesis of cryptococcosis is similar to that of tuberculosis, and cell-mediated immunity plays a very important role in the outcome of infection. Infection usually occurs by inhalation. Pulmonary infection may be asymptomatic or may cause mild or severe pneumonia. People with HIV disease, malignancies, and persons under immunosuppression are at high risk of developing disseminated disease. Dissemination of infection can occur with involvement of multiple sites including the central nervous system, skin, prostate, and eyes.
Cryptococcal meningitis is the most serious form of infection and may resemble tuberculous or any other chronic form of meningitis. It is one of the common opportunistic infections in patients with AIDS; mortality of HIV-associated cryptococcal meningitis is high.
The polysaccharide capsule contributes to the virulence of the organism as it interferes with a variety of immunological functions of the host such as leukocyte migration, cytokine production, and phagocytosis. 3 other products synthesized by C. neoformans, namely mannitol, melanin, and prostaglandins, are also thought to affect the host immune response and thus contribute to the virulence of the organism.
Laboratory diagnosis of cryptococcal meningitis depends on the microscopic demonstration of the large yeast cells (5-10 microns) with prominent capsules in India ink preparation, cultural isolation of the organism, and detection of polysaccharide capsular antigen in the CSF by latex agglutination test.
Urease production and inability to ferment sugars help to differentiate cryptococcus from other yeasts, while ability to grow at 37°C helps to differentiate C. neoformans from other cryptococcus species. Ability to produce phenol oxidase, which breaks down diphenolic compounds into melanin, is another test for C. neoformans and can be detected using special media.
The serological test for detection of capsular antigen in CSF is rapid, specific, and sensitive. Latex agglutination or ELISA can be used, and the antigen can be detected in serum as well. In a patient undergoing antifungal therapy, high antigen titer indicates high burden of yeasts, poor immune response, and hence poor prognosis.
Histoplasma capsulatum is a thermally dimorphic fungus and is a soil saprophyte. It produces yeast forms in tissues and on enriched media at 37°C and does not possess capsule. On Sabouraud’s agar at 25°C to 30°C, it produces mycelial growth. The fungus causes histoplasmosis. CNS involvement leading to chronic meningitis can occur as a result of hematogenous dissemination. Risk factors for disseminated histoplasmosis include AIDS, hematological malignancies, organ transplants, and immunosuppressive therapy with agents like corticosteroids and tumor necrosis factor antagonists. Infants and the elderly also are at risk of developing severe illness after exposure.
Candida albicans and Candida glabrata are yeast-like fungi and belong to the normal flora of skin, mucous membrane, and gastrointestinal tract. Candida albicans appears as non-encapsulated oval budding cells (3-6 microns) with pseudohyphae. Tissue invasion is associated with formation of mycelia. Germ tube formation, when incubated in human serum, and production of thick-walled spherical chlamydospores on corn meal agar are used for differentiating C. albicans from other species. C. albicans produces a variety of opportunistic superficial infections such as thrush, vulvovaginitis, onychomycosis, and cutaneous candidiasis. It can cause systemic candidiasis in immunocompromised hosts and chronic mucocutaneous candidiasis in children with cellular immune deficiencies. Prolonged antibiotic therapy is another predisposing factor for candida infections. Nosocomial candidiasis is not uncommon.
Candida meningitis is not common and occurs among low birth weight infants and HIV-positive persons or as a terminal complication of severe diseases like leukemia. Detection of candida antigen mannan in CSF is reported to help rapid diagnosis. Mannan or mannoprotein is a cell wall component of candida.
In recent years C. glabrata has emerged as a more frequent cause of mucosal and invasive infections. This is thought to be due to the intrinsic and acquired resistance of this candida species to the azole group of antimycotic agents.
Trichosporon asahii is a yeast-like fungus that is being increasingly recognized as an opportunistic pathogen causing invasive infections, especially in granulocytopenic and immunocompromised hosts. Chronic meningitis is described as one of the clinical manifestations of T. asahii infection. The fungus is also reported to be associated with hypersensitivity pneumonitis. Infection in immunocompetent individuals is mostly characterized by superficial cutaneous involvement. T.asahii grows on Sabouraud’s medium, producing wrinkled colonies that contain budding yeasts, hyphae, and arthroconidia.

Question 4

What is likely to be a characteristic of this fungus?

1 Mycelial growth with non-septate hyphae
2 Growth of yeast forms at 25°C
3 Mycelial growth with septate hyphae at 37°C
4 Thermal dimorphism
5 Causes cutaneous mycosis

Answer 4

Thermal dimorphism

The fungal elements in the biopsy tissue from the non-healing ulcer associated with nodular lymphangitis are likely to be that of Sporothrix schenckii, which shows characteristic thermal dimorphism. Thermal dimorphism is a characteristic of this fungus as it occurs in 2 different morphological forms depending on the temperature. Yeast forms are seen in the infected tissue and when grown in vitro at 35-37°C. Formation of mycelial phase is seen in nature and at room temperature (25-30 degrees).
Sporothrix schenckii occur as small oval, spindle shaped, or cigar shaped yeast cells in infected tissue and when grown at 37° in vitro. When cultured on Sabouraud’s medium at 25°, produces grey to black colonies which become wrinkled and fuzzy with age. These colonies contain very thin (1-2 micron diameter) branching septate hyphae and small conidia (3-5 microns) arranged in flower-like clusters at the ends of tapering conidiophores.
Sporothrix schenckii causes subcutaneous mycosis known as sporotrichosis, a chronic granulomatous infection. The disease is characterized by development of nodules in skin and subcutaneous tissues which suppurate and break down to form indolent ulcers. The draining lymphatics become thickened and cord like. Multiple nodules develop along the lymphatics which also subsequently ulcerate. Disease characterized by single fixed nodule without involvement of lymphatics may be produced especially in endemic areas. Localization of infection occurs due to immunity.
The infection is reported to be endemic in Mexico and South America.
Lymphocutaneous infection, clinically resembling sporotrichosis, may be caused by other organisms like Nocardia brasiliensis, Mycobacterium marinum and Leishmania braziliensis. In the US, S. schenckii is the most commonly reported cause of this manifestation. Culture of biopsy specimen is important in confirming diagnosis.
S. schenckii occurs in nature as a saprophyte on plants, soil, timber, and a variety of vegetations. Infection usually occurs following thorn pricks or minor injuries and the fungal hyphal fragment or conidia being introduced through the traumatized skin. The disease is more often associated with certain occupations like in horticulturists, florists, and those engaged in gardening, farming, and hunting. Zoonotic transmission can also occur following contact with infected cats, dogs, and horses. Several cases of sporotrichosis acquired from cats have been reported from Brazil.
Systemic spread occurs rarely, causing arthritis or with involvement of central nervous system. Disseminated infections in immunocompromised patients have been reported.
Potassium iodide and itraconazole are used for treatment. In disseminated infections amphotericin B is given.
Cutaneous mycosis is the fungal infection affecting the superficial keratinized tissue and involves skin, hair, and nails. The most important causative agents are dermatophytes belonging to 3 genera: trichophyton, epidermophyton, and microsporum.

Question 5

What is the most likely pathohistological feature of the causative agent?

1 Spherules with endospores
2 Broad-based budding
3 Tuberculate macroconidium
4 Gram-positive diplococci
5 Gram-negative rods

Answer 5

Spherules with endospores

The correct answer is spherules with endospores. This patient has pneumonia with a travel history to the Southwest (New Mexico), and erythema nodosum, which is characteristic of Coccidioides. When the soil is disrupted, the arthroconidia can become airborne and, if inhaled by a susceptible host, produce infection. Localized in the pulmonary acinus, the arthrospore sheds its outer coating, swells, and becomes a spherical structure, i.e., the spherule.
Broad-based budding is seen in Blastomycosis.
Tuberculate macroconidium is seen in Histoplasmosis. Histoplasmosis is more common in the Ohio River Valley.
This patient does not have a bacterial infection. The patient has a dry cough, with a fever, pleuritic chest pain, as well as a travel history to an endemic area of Coccidioides.

Question 6

What is the best treatment for this disease?

1 Ciprofloxacin
2 Doxycycline
3 Itraconazole
4 Rifampin
5 Tetracycline

Answer 6

Itraconazole

This is a typical case of Sporothrix schenckii infection. This fungus is found in the Mississippi and Missouri valleys. Usually, the fungus is inoculated in the skin by a puncture with a thorn from roses or conifers. About 1-12 weeks after the puncture, the patient presents with a papule or nodule that sometimes gets ulcerated, and adenopathy develops along the lymphatic chain. Diagnosis is by biopsy where cigar-shaped bodies are seen. Classically, the treatment was potassium iodide, but antifungal medicines such as itraconazole (Sporanox) are used more commonly now.
Ciprofloxacin is a fluoroquinolone that is active against many Gram-negative and Gram-positive organisms. It is commonly used to treat sinusitis and respiratory infections.
Doxycycline is a tetracycline that is also active against many Gram-negative and positive organisms in addition to syphilis and Lyme disease.
Rifampin is a most commonly used to treat tuberculosis. It may also be used to treat some staphylococcus and streptococcal species.
Tetracycline is used to treat many Gram-positive and Gram-negative organisms, as well as rickettsial disease, chlamydia, and mycoplasma infections.

Question 7

Transmission of Pneumocytis carinii occurs by which of the following?

1 Inhalation
2 Skin contact
3 Sexual contact
4 Infected needles
5 Animal vectors

Answer 7

Inhalation

Transmission of Pneumocytis carinii occurs by inhalation, and infection is prominent in the lungs. Pneumonia occurs when host defenses are reduced.

Question 8

Tinea cruris (jock itch) is caused by which of the following?

1 Epidermophyton floccosum
2 Microsporum canis
3 Tinea mentagrophytes
4 Tinea tonsurans
5 Cytomegalovirus

Answer 8

Epidermophyton floccosum

Tinea cruris (jock itch) is caused by Epidermophyton floccosum. Microsporum canis causes tinea corporis or ringworm, tinea mentagrophytes causes athlete’s foot, tinea tonsurans causes tinea capitis, and cytomegalovirus causes cytomegalovirus inclusion disease.

Question 9

Chromomycosis is a slowly progressive granulomatous infection of the skin caused by

1 Phialophora verrucosa
2 Epidermophyton floccosum
3 Tinea rubrum
4 Tinea tonsurans
5 Microsporum canis

Answer 9

Phialophora verrucosa

Chromomycosis is a slowly progressive granulomatous infection of the skin caused by Phialophora verrucosa. Epidermophyton floccosum, tinea rubrum, tinea tonsurans, and microsporum canis are all fungi that cause infection of the superficial layer of the skin.

Question 10

Which one of the following is a subcutaneous fungus

1 Phialophora verrucosa
2 Epidermophyton floccosum
3 Tinea rubrum
4 Tinea tonsurans
5 Microsporum canis

Answer 10

Phialophora verrucosa

Chromomycosis is a slowly progressive granulomatous infection of the skin caused by Phialophora verrucosa. Epidermophyton floccosum, tinea rubrum, tinea tonsurans, and microsporum canis are all fungi that cause infection of the superficial layer of the skin.

Question 11

Coccidioides immitis is a systemic fungus that is transmitted by inhalation of

1 Arthrospores
2 Spherules
3 Aerosol-droplet
4 Zygospores
5 Ascospores

Answer 11

Arthrospores

Coccidioides immitis is systemic fungus that is transmitted by inhalation of arthrospores and not spherules, aerosol-droplet, zygospores, or ascospores.

Question 12

The ascomycetous sexual stage of the fungus Histoplasma capsulatum is called:

1 Emmonsiella capsulata
2 Epidermophyton floccosum
3 Zygospores
4 Ascospores
5 Blastospores

Answer 12

Emmonsiella capsulata

The ascomycetous sexual stage of the fungus Histoplasma capsulatum is called Emmonsiella capsulata and not Epidermophyton floccosum, zygospores, ascospores, or blastospores.
Cognitive Level: Remember

Question 13

Histoplasma capsulatum infection occurs via

1 Inhalation of conidia
2 Fecal-oral route
3 Tick bite
4 Louse bite
5 Contaminated water

Answer 13

Inhalation of conidia

Histoplasma capsulatum infection occurs via inhalation of conidia and not by fecal-oral route, louse or tick bite, or contaminated water.

Question 14

A distinguishing feature of Cryptococcus neoformans is the presence of

1 Carbohydrate capsule
2 Peptidoglycan
3 Teichoic acids
4 Golgi bodies
5 Endoplasmic reticulum

Answer 14

Carbohydrate capsule

A distinguishing feature of Cryptococcus is the presence of a wide carbohydrate capsule both in culture and in tissues. Peptidoglycan and teichoic acids are found in bacterial cell walls and golgi bodies. The endoplasmic reticulum are parts of eukaryotic cells.

Question 15

Cryptococcus neoforman differs from non-pathogenic cryptococci in that it grows at

1 25° C
2 30° C
3 35°C
4 37°C
5 40°C

Answer 15

37°C

Cryptococcus neoformans differs from non-pathogenic cryptococci in that it grows at 37°C and not at 25°C, 30°C, 35°C, or 40°C.

Question 16

If the skin manifestations are due to a fungal infection confined to the stratum corneum, what fungus is most likely to be the etiological agent of this condition?

1 Piedraia hortae
2 Microsporum canis
3 Trichophyton rubrum
4 Malassezia furfur
5 Epidermophyton floccosum
6 Hortaea werneckii

Answer 16

Malassezia furfur

Appearance of lesions that fluoresce under Wood’s lamp is characteristic of Pityriasis versicolor, a superficial mycosis confined to the stratum corneum. Malassezia furfur, a yeast-like lipophilic fungus is the etiological agent of Pityriasis versicolor. Stratum corneum contains dead keratin-filled cells that have migrated from the basal layer and the fungus lives in this layer, eliciting minimal inflammatory response. Pityriasis versicolor is a common affliction and is mainly a cosmetic problem. Microscopic examination of skin scrapings in 10-20% KOH will show short unbranched hyphae and spherical yeast-like cells giving characteristic “spaghetti and meatball” appearance. The fungus can be grown on Sabouraud’s agar covered with a layer of olive oil. Pityriasis versicolor is treated with applications of selenium sulphide. Topical or oral azoles are also effective. Some individuals develop folliculitis due to Malassazia. Rarely the fungus causes opportunistic fungemia in patients (usually infants) receiving total parenteral nutrition, as a result of contamination of the lipid emulsion.
Piedra hortai causes black piedra, a nodular infection of the hair shaft.
Microsporum canis, Trichophyton rubrum, and Epidermophyton floccosum are dermatophytes. They infect only the superficial keratinized tissue (skin, hair, and nail). Though infection is confined to the cornified layer of the skin and its appendages, a variety of inflammatory and allergic responses are induced by the presence of the fungi and their metabolic products. In skin scrapings, the dermatophytes are detected by the presence of hyaline, septate, branching hyphae, or chains of arthroconidia.
Hortaea wernickii (Cladosporium wernickii) is a dematiaceous fungus associated with Tinea nigra, a localized infection of the stratum corneum, particularly of the palms. Lesions appear as black or brownish discoloration. Microscopic examination of skin scrapings will reveal branched septate hyphae and budding cells with melaninized cell walls.

Question 17

Which of the following is commonly implicated in tinea pedis

1 Microsporum audouinii, Microsporum canis, and Trichophyton tonsurans
2 Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum
3 Epidermophyton floccosum, Trichophyton tonsurans, and Microsporum canis
4 Trichophyton schoenleinii and Microsporum audouinii

Answer 17

Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum

Tinea pedis, commonly referred to as athlete’s foot, is the fungal infection of feet. Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum are the dermatophytes commonly implicated in tinea pedis. The lesions appear on the interdigital space of the person wearing shoes. Infection causes itching between the toes and vesicle formation. Itching can lead to rupture of vesicle and fluid discharge. Maceration and peeling of the skin of the toe web can cause the crack in the skin leading to a secondary bacterial infection.
Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum are also associated with tinea cruris (jock itch) and tinea unguium (infection of nail).
Microsporum audouinii, Microsporum canis, and Trichophyton tonsurans are common causes of tinea capitis (Ringworm of the scalp).
Trichophyton schoenleinii is associated with tinea favosa, an acute infection of the hair and follicles. This dermatophyte forms scutula around infected hair follicles leading to permanent hair loss.

Question 18

Dematiaceous fungi cause chronic, granulomatous infection typically confined to the skin and subcutaneous tissues of the feet and legs known as

1 Histoplasmosis
2 Dermatophytoses
3 Chromoblastomycosis
4 Zygomycosis

Answer 18

Chromoblastomycosis

Traumatic implantation of dematiaceous fungus can lead to slowly progressive granulomatous infection of skin and subcutaneous tissue, which is known as chromoblastomycosis. The infection is characterized by appearance of small scaly papule at the site of implantation leading to slow development of verrucous nodules. Lesions of chromoblastomycosis are more common in lower legs and feet. Verrucous nodules may vegetate and develop cauliflower like appearance. Lesions may spread to other areas of the skin by autoinoculation or lymphatic drainage. Direct microscopic examination reveal pigmented hyphal elements at skin surface and chestnut brown colored muriform cells (cells having cross-walls in two directions).
The common etiological agents of chromoblastomycosis include following:
Cladosporium carrionii
Fonsecaea pedrosoi
Fonsecaea compacta
Rhinocladiella aquaspersa
Phialophora verrucosa
Diagnosis:
The direct microscopic examination and histopathological examination are as follows:
Epidermis shows pseudoepitheliomatous hyperplasia.
Biopsy of infected lesions reveals tissue forms of fungus known as sclerotic bodies.
Crust and skin scraping demonstrates brown branching hyphae.
Pus or biopsy specimen of epidermal and subcutaneous tissue may demonstrate thick walled round cells with septa.

Question 19

Piedraia hortae is the etiological agent of

1 White piedra
2 Black piedra
3 Tinea manuum
4 Tinea corporis
5 Busse-Buschke’s disease

Answer 19

Black piedra

Piedraia hortae is a superficial mycose and causes black piedra. Black piedra is a superficial infection of hair shaft characterized by a hard, black nodule attached to the hair shaft. Piedraia hortae mostly infects scalp hair and does not penetrate the cortex of the hair shaft. The nodule consists of asci and ascospores. The infection usually occurs in tropical areas of South America, the pacific islands, and eastern Asia.
Direct microscopic examination of infected hair in 10% KOH preparation will reveal black, hard, gritty nodules composed of fungal cells. Examination of crushed nodules can show asci containing ascospores with single polar filaments at each end, and dark brown hyphae. Treatment includes shaving or cutting the infected hair.
The following table indicates the etiological agents of the fungal infection given in the question:

Disease Etiological Agent
Busse-buschke’s disease Cryptococcus neoformans
White peidra Trichosporon beigelii
Tinea favosa Trichophyton schoenleinii
Tinea magnum Trichophyton rubrum,
Trichophyton mentagrophytes

Question 20

Microsporum is a dermatophyte and can be identified by its ability to produce

1 Macroconidia
2 Basidiospores
3 Favic-chandelier
4 Zygospores
5 Germ tubes

Answer 20

Macroconidia

Microsporum is implicated in dermatophytosis that involves hair and skin infection, but not the infection of nails. This species invades ectothrix of hair and forms dense sheaths of spores in a mosaic pattern around the hair. Microsporum infected hairs fluoresce when examined under Wood’s lamp. Microsporum produces large, rough walled, many celled macroconidia.
Microsporum audouinii is an anthropophilic dermatophyte associated with epidemic tinea capitis. Microsporum canis is associated with zoophilic tinea capitis (nonepidemic). Microsporum belongs to Ascomycotina and produces ascospores.
Basidiospores are produced by fungi grouped under Basidiomycotina such as Cryptococcus neoformans.
Favic-chandelier is an antler shaped hyphae produced by Trichophyton schoenleinii, causative agent of Tinea favosa.
Candida albicans is known to produce germ tube.
Opportunist pathogen such as Rhizopus nigrans produces large thick walled zygospores.

Question 21

Which of the following is an anthropophilic dermatophyte that is associated with epidemic type tinea capitis and fluoresces under Wood’s lamp?

1 Microsporum canis
2 Microsporum audouinii
3 Epidermophyton Floccosum
4 Trichophyton schoenleinii
5 Trichophyton verrucosum

Answer 21

Microsporum audouinii

Microsporum is implicated in dermatophytosis that involves hair and skin infection, but not the infection of nails. Microsporum species invades ectothrix of hair and form dense sheaths of spores in a mosaic pattern around the hair. Microsporum infected hairs fluoresce when examined under Wood’s lamp. Microsporum produces large, rough walled, many-celled macroconidia.
Microsporum audouinii is a anthropophilic dermatophyte associated with epidemic tinea capitis. It fluoresces bright yellow green when examined under Wood’s lamp.
Microsporum canis is associated with zoophilic tinea capitis (nonepidemic) and invades ectothrix of hair and fluoresces bright yellow-green under Wood’s lamp and when isolated produces abundant, rough walled, spindle shaped, and many-celled macroconidia.
Epidermophyton Floccosum is an anthropophilic dermatophyte that does not infect hair, but invades skin and nail only. It does not fluoresce when examined under Wood’s lamp. It is mostly implicated in tinea pedis, tinea cruris, and tinea unguium. It produces club shaped 1 to 5-celled macroconidia.
Trichophyton schoenleinii is an anthropophilic dermatophyte associated with favic hair invasion referred to as tinea favosa. The mycose produces scutulum, which is a waxy mass of hyphal elements around the hair follicle at the scalp line. Microscopic examination of hair in KOH preparation reveals hyphae without the spores throughout the hair forming tunnels and air bubbles at the point of degeneration. When incubated for 2-3 weeks the microscopic examination of the colony reveals characteristic antler hyphae known as favic-chandelier.
Trichophyton verrucosum is zoophilic dermatophyte often seen in cattle and is the most common agent implicated in tinea barbae in dairy areas. It produces characteristic chain of chlamydospores when thiamin rich media is incubated at 37° C.

Question 22

Which of the following is a zoophilic dermatophyte often seen in cattle that produces a characteristic chain of chlamydospores?

1 Microsporum canis
2 Microsporum audouinii
3 Epidermophyton Floccosum
4 Trichophyton schoenleinii
5 Trichophyton verrucosum

Answer 22

Trichophyton verrucosum

Microsporum is implicated in dermatophytosis that involves hair and skin infection, but not the infection of nails. Microsporum species invades ectothrix of hair and form dense sheaths of spores in a mosaic pattern around the hair. Microsporum infected hairs fluoresce when examined under Wood’s lamp. Microsporum produces large, rough walled, many-celled macroconidia.
Microsporum audouinii is a anthropophilic dermatophyte associated with epidemic tinea capitis. It fluoresces bright yellow green when examined under Wood’s lamp.
Microsporum canis is associated with zoophilic tinea capitis (nonepidemic) and invades ectothrix of hair and fluoresces bright yellow-green under Wood’s lamp and when isolated produces abundant, rough walled, spindle shaped, and many-celled macroconidia.
Epidermophyton Floccosum is an anthropophilic dermatophyte that does not infect hair, but invades skin and nail only. It does not fluoresce when examined under Wood’s lamp. It is mostly implicated in tinea pedis, tinea cruris, and tinea unguium. It produces club shaped 1 to 5-celled macroconidia.
Trichophyton schoenleinii is an anthropophilic dermatophyte associated with favic hair invasion referred to as tinea favosa. The mycose produces scutulum, which is a waxy mass of hyphal elements around the hair follicle at the scalp line. Microscopic examination of hair in KOH preparation reveals hyphae without the spores throughout the hair forming tunnels and air bubbles at the point of degeneration. When incubated for 2-3 weeks the microscopic examination of the colony reveals characteristic antler hyphae known as favic-chandelier.
Trichophyton verrucosum is zoophilic dermatophyte often seen in cattle and is the most common agent implicated in tinea barbae in dairy areas. It produces characteristic chain of chlamydospores when thiamin rich media is incubated at 37° C.

Question 23

Which of the following is an anthropophilic dermatophyte that causes favic hair invasion by scutula formation?

1 Microsporum canis
2 Microsporum audouinii
3 Epidermophyton Floccosum
4 Trichophyton schoenleinii
5 Trichophyton verrucosum

Answer 23

Trichophyton schoenleinii

Microsporum is implicated in dermatophytosis that involves hair and skin infection, but not the infection of nails. Microsporum species invades ectothrix of hair and form dense sheaths of spores in a mosaic pattern around the hair. Microsporum infected hairs fluoresce when examined under Wood’s lamp. Microsporum produces large, rough walled, many-celled macroconidia.
Microsporum audouinii is a anthropophilic dermatophyte associated with epidemic tinea capitis. It fluoresces bright yellow green when examined under Wood’s lamp.
Microsporum canis is associated with zoophilic tinea capitis (nonepidemic) and invades ectothrix of hair and fluoresces bright yellow-green under Wood’s lamp and when isolated produces abundant, rough walled, spindle shaped, and many-celled macroconidia.
Epidermophyton Floccosum is an anthropophilic dermatophyte that does not infect hair, but invades skin and nail only. It does not fluoresce when examined under Wood’s lamp. It is mostly implicated in tinea pedis, tinea cruris, and tinea unguium. It produces club shaped 1 to 5-celled macroconidia.
Trichophyton schoenleinii is an anthropophilic dermatophyte associated with favic hair invasion referred to as tinea favosa. The mycose produces scutulum, which is a waxy mass of hyphal elements around the hair follicle at the scalp line. Microscopic examination of hair in KOH preparation reveals hyphae without the spores throughout the hair forming tunnels and air bubbles at the point of degeneration. When incubated for 2-3 weeks the microscopic examination of the colony reveals characteristic antler hyphae known as favic-chandelier.
Trichophyton verrucosum is zoophilic dermatophyte often seen in cattle and is the most common agent implicated in tinea barbae in dairy areas. It produces characteristic chain of chlamydospores when thiamin rich media is incubated at 37° C.

Question 24

Which of the following is a zoophilic dermatophyte that invades ectothrix of hair and fluoresces bright yellow-green under wood’s lamp and when isolated, produces abundant, rough walled, spindle shaped, and many celled macroconidia

1 Microsporum canis
2 Microsporum audouinii
3 Epidermophyton Floccosum
4 Trichophyton schoenleinii
5 Trichophyton verrucosum

Answer 24

Microsporum canis

Microsporum is implicated in dermatophytosis that involves hair and skin infection, but not the infection of nails. Microsporum species invades ectothrix of hair and form dense sheaths of spores in a mosaic pattern around the hair. Microsporum infected hairs fluoresce when examined under Wood’s lamp. Microsporum produces large, rough walled, many-celled macroconidia.
Microsporum audouinii is a anthropophilic dermatophyte associated with epidemic tinea capitis. It fluoresces bright yellow green when examined under Wood’s lamp.
Microsporum canis is associated with zoophilic tinea capitis (nonepidemic) and invades ectothrix of hair and fluoresces bright yellow-green under Wood’s lamp and when isolated produces abundant, rough walled, spindle shaped, and many-celled macroconidia.
Epidermophyton Floccosum is an anthropophilic dermatophyte that does not infect hair, but invades skin and nail only. It does not fluoresce when examined under Wood’s lamp. It is mostly implicated in tinea pedis, tinea cruris, and tinea unguium. It produces club shaped 1 to 5-celled macroconidia.
Trichophyton schoenleinii is an anthropophilic dermatophyte associated with favic hair invasion referred to as tinea favosa. The mycose produces scutulum, which is a waxy mass of hyphal elements around the hair follicle at the scalp line. Microscopic examination of hair in KOH preparation reveals hyphae without the spores throughout the hair forming tunnels and air bubbles at the point of degeneration. When incubated for 2-3 weeks the microscopic examination of the colony reveals characteristic antler hyphae known as favic-chandelier.
Trichophyton verrucosum is zoophilic dermatophyte often seen in cattle and is the most common agent implicated in tinea barbae in dairy areas. It produces characteristic chain of chlamydospores when thiamin rich media is incubated at 37° C.

Question 25

Which of the following mycose has predilection for lymphatic system and is associated with rose gardener syndrome?

1 Trichosporon beigelii
2 Trichophyton tonsurans
3 Trichophyton verrucosum
4 Sporothrix schenckii

Answer 25

Sporothrix schenckii

Sporothrix schenckii is a dimorphic fungus found on plants or woods that causes sporotrichosis when traumatically introduced into the skin.. Sporotrichosis is a chronic granulomatous infection characterized by nodular lesions of cutaneous or subcutaneous tissues and adjacent lymphatics. The subcutaneous nodule can develop into buboes. Nodules breaks down as the mycotic agent grows within the lesion and penetrates the skin to form ulcers along the lymph channels that may persist for months or years. Sporotrichosis occurs world wide in all age groups and is inoculated in the skin by thorn pricks, splinters, sphagnum moss, grasses, or garden soil. It is an occupational disease of gardeners, foresters, and horticulturists.
Lymphocutaneous sporotrichosis is associated with rose cultivation, as the mycotic agent is found on thorns. Penetrating wound caused by thorns can cause subsequent infection in the rose gardener and, therefore it is also called rose gardener syndrome in the United States.
Trichosporon beigelii, Trichophyton verrucosum, and Trichophyton tonsurans are associated with superficial mycoses.
Trichosporon beigelii causes white piedra which is infection of the hair shaft.
Trichophyton verrucosum is commonly implicated in acute or chronic folliculitis of the, beard, neck, or face in dairy areas.
Trichophyton tonsurans is associated with black dot tinea capitis which is characterized by hair breakage and filling of follicles with dark conidia.

Question 26

Etiological agent of systemic mycoses includes:

1 Histoplasma capsulatum
2 Trichophyton rubrum
3 Fonsecaea compacta
4 Exophiala spinifera
5 Piedra hortae

Answer 26

Histoplasma capsulatum

Systemic mycoses, also referred to as deep mycoses, are caused by geophilic fungi, and infection is acquired by inhalation, causing primary pulmonary infection. These pathogenic fungi invade the body of a healthy compromised individual and cause disease. Etiological agents of systemic mycoses are mostly dimorphic in nature.
The 4 classic agents of systemic mycoses are as follows:
Histoplasma capsulatum.
Coccidioides immitis.
Blastomyces dermatitidis.
Paracoccidioides brasiliensis.
Histoplasma capsulatum is the etiological agent of histoplasmosis, an intracellular mycosis of reticuloendothelial system. The fungus grows within macrophages and giant cells.
Patchy bronchopneumonia containing yeast-laden phagocytic cells develop in alveolar spaces after inhalation of conidia.
Trichophyton rubrum is a dermatophyte commonly implicated in infection of skin, nail, and hair.
Fonsecaea compacta and Exophiala spinifera are agents of subcutaneous mycosis.
Peidra hortae is an etiological agent of black piedra, an infection of hair shaft.

Question 27

Darling’s disease is caused by

1 Inhalation of yeast form of Blastomyces dermatitidis
2 Inhalation of conidia or hyphal fragments of Histoplasma capsulatum
3 Penetration of the skin by ascospores of Microsporum canis
4 Penetration of skin by hyphae of Trichophyton tonsurans

Answer 27

Inhalation of conidia or hyphal fragments of Histoplasma capsulatum

Histoplasma capsulatum is the causative agent of histoplasmosis that is also known as Darling’s disease. This chronic, granulomatous infection results from inhalation of arthroconidia or hyphal fragments of Histoplasma capsulatum. The organism causes initial infection in the lungs and eventually invades the reticuloendothelial system. Histoplasma capsulatum grows in the soil rich in nitrogen content and contaminated with bird and bat droppings.
In the United States, histoplasmosis is endemic in the Ohio and Mississippi Valley regions. 80% or more of the long-term residents in these regions have been infected with Histoplasma capsulatum according to the surveys of skin test reactivity to histoplasmin. Approximately 95% of cases are asymptomatic and are self-limited. However, depending on inoculum size, lung structure and immune status of the host disease can be severe. Amphotericin B is the primary choice of drug for severe form of histoplasmosis.
Other names of histoplasmosis are:

Reticuloendothelial cytomycosis.
Spelunker’s disease.
Darling’s disease.
Cave disease.

Question 28

Which of the following is an etiological agent of desert rheumatism?

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 28

Coccidioides immitis

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 29

Which of the following is an etiological agent of South American blastomycosis?

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 29

Paracoccidioides brasiliensis

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 30

The mycelial form of this fungi produces alternate, thick walled, barrel shaped arthroconidia.

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 30

Coccidioides immitis

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 31

The yeast phase of this mycotic agent is characterized by multipolar budding and appears as “mariner’s wheel” or “Mickey Mouse Cap.”

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 31

Paracoccidioides brasiliensis

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 32

Which of the following is the etiological agent of Gilchrist’s disease, or North American blastomycosis?

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 32

Blastomyces dermatitidis

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 33

Which of the following is the etiological agent of the most prevalent pulmonary mycosis of human and animals in the United States?

1 Histoplasma capsulatum
2 Coccidioides immitis
3 Blastomyces dermatitidis
4 Paracoccidioides brasiliensis

Answer 33

Histoplasma capsulatum

Systemic mycoses are infections caused by the inhalation of the mycotic agent and originate primarily in the lungs but may spread to other organs of the body. Dimorphic pathogenic fungi associated with systemic mycoses include all of the following:
Histoplasma capsulatum
Coccidioides immitis
Blastomyces dermatitidis
Paracoccidioides brasiliensis
None of these dimorphic agents of systemic mycosis are encapsulated. Cryptococcus neoformans is the monomorphic encapsulated yeast associated with systemic mycoses.
Coccidioidomycosis is endemic in the areas with semiarid climate, which include Maricopa and Pima counties of Arizona, San Joaquin Valley of California, and Southwestern Texas in the United States. Coccidioidomycosis is also known as San Joaquin Valley fever, Posada’s Disease, and desert rheumatism.
Coccidioides immitis is the causative agent of coccidioidomycosis that may be manifested as primary pulmonary infection or as a progressive, disseminated granulomatous infection. Disseminated coccidioidomycosis may involve skin, bone, joints, visceral organs, and meninges. Desert rheumatism is arthritic allergic manifestation of coccidioidomycosis. Other allergic manifestation may include toxic erythema, erythema multiforme, or erythema nodosum. The infection is acquired through inhalation of arthroconidia. Arthroconidia germinates to develop into spherule containing endospores. The spherule is the tissue phase of Coccidioides immitis and can be observed by microscopic examination of the tissue in pus or in sputum. When cultured, Coccidioides immitis hyphal colony produces alternate, barrel shaped, thick walled arthroconidia.
Individuals who inhale the arthroconidia of Coccidioides immitis and become infected acquire a positive delayed type of hypersensitive response. Skin testing done using coccidioidin can elicit delayed type of hypersensitive reaction. A positive skin test is defined as induration that is greater than 5mm in diameter. Serological testing can be done for diagnosis and management of coccidioidomycosis.
Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis that is also known as South American blastomycosis, or Lutz-Splendore-Almeida’s disease. It may be manifested primarily as pulmonary infections that are mostly asymptomatic or more frequently as ulcerative granulomatous lesions of the oral and nasal cavity. Paracoccidioidomycosis is restricted to South and Central America with higher incidence in Brazil, Venezuela, and Colombia. The infection is acquired by inhalation of conidia that converts to yeast phase inside the tissue. When KOH preparation of the infected specimen is examined under microscope, the fungus appear as budding yeast cells with multipolar budding. The multiple budding at the periphery of the parent yeast cell appears as “mariner’s wheel,” or “Mickey Mouse Cap,” when very few buds are present on the parent yeast cell. Serodiagnosis for paracoccidioidomycosis can be done using complement fixation or immunodiffusion procedures.
Histoplasma capsulatum is the etiological agent of histoplasmosis, the most prevalent pulmonary mycosis of humans and animals in the United States. Histoplasmosis is an intracellular mycosis of the reticuloendothelial system acquired by inhalation of conidia. Histoplasma capsulatum grows in soil rich in nitrogen content and contaminated with bird and bat droppings. In the United States, it is endemic in the Ohio and Mississippi Valley regions.
Histoplasma capsulatum forms an oval, uninucleate budding cell in phagocyte and when grown in tissue cultures at 37°C. When grown on Sabouraud’s agar that is incubated at room temperature, the colony develops as a mold and consists of tuberculate macroconidia, microconidia, or both. Tuberculate macroconidia are the large, spherical, thick-walled conidia with finger-like projections.
Histoplasma capsulatum can cause acute or chronic primary pulmonary infections or can be disseminate to other organs. Heavy exposure to the organism can lead to acute pulmonary histoplasmosis. Dissemination mostly involves reticuloendothelial system that includes lymph nodes, liver, spleen, and bone marrow and is characterized by development of calcified lesions. Disseminated histoplasmosis may be benign or may be acute and progressive. A fatal form of acute progressive histoplasmosis is seen in AIDS patients, patients receiving immunosuppressive drugs, or individuals with any immunocompromised conditions. The disease is characterized by continued intracellular replication of Histoplasma capsulatum yeast within macrophages that may effect every organ of the body. Patients may present with anemia, leukopenia, weight loss, hepatosplenomegaly, and granulomatous lesions in the reticuloendothelial system. Complement fixation test and Immunodiffusion test are commonly used serological tests for diagnosis of histoplasmosis.
Blastomyces dermatitidis causes blastomycosis, which is acquired by inhalation of conidia. Conidia are phagocytized by macrophage and are converted to yeast form and carried to other organs. Blastomyces dermatitidis exists in the tissue as broad based budding yeast cells. Blastomycosis is also known as North American blastomycosis, Gilchrist’s disease, and Chicago disease. Most common clinical presentation includes chronic cutaneous disease and osseous disease. Blastomycosis is endemic in the Ohio and Mississippi Valley regions, Minnesota, Southern Manitoba, and Southwest Ontario.

Question 34

Rhinocerebral zygomycosis is caused by

1 Epidermophyton floccosum
2 Blastomyces dermatitidis
3 Trichophyton rubrum
4 Rhizopus arrhizus
5 Malassezia furfur

Answer 34

Rhizopus arrhizus

Rhinocerebral infection is the most common form of zygomycosis and is frequently caused by Rhizopus arrhizus. Rhinocerebral zygomycosis mostly involves patients suffering from diabetic ketoacidosis. The fungus invades nasal turbinates and paranasal sinuses and then progresses to the nose, eyes, and brain leading to invasion of blood vessels and destruction of cranial nerves.
Infection may be characterized by the following symptoms:
Sinusitis.
Black and blood tinged nasal discharge.
Necrosis of nasal septum and turbinates.
Periorbital edema.
Paralysis of the eye muscles.
Proptosis.
Signs of meningoencephalitis.
Epidermophyton floccosum and Trichophyton rubrum are dermatophytes commonly associated with tinea pedis, tinea cruris, and tinea unguium. Blastomyces dernatitidis is a dimorphic fungi that causes North American blastomycosis. Malassezia furfur is associated with pityriasis versicolor which is a chronic superficial infection of the stratum corneum.

Question 35

Rhizoids are present at the base of sporangiophores with black sporangia containing one celled, unbranched, globose sporangiophores. Match the morphological description given with the appropriate fungus from the choices given in A through E

1 Absidia
2 Mucor
3 Rhizopus
4 Candida albicans
5 Aspergillus fumigatus

Answer 35

Rhizopus

Aspergillus fumigatus is commonly associated with infection in immunocompromised patients and is also implicated in invasive aspergillosis. Culture of Aspergillus fumigatus appears blue green to gray green and microscopic examination of the colonies reveals septate hyphae giving rise to conidiophores with vesicle bearing uniseriate phialids. Aspergillus fumigatus can tolerate the temperature of >45°C. Absidia, Mucor, and Rhizopus are the molds that belong to class Zygomycetes and are associated with opportunistic infection known as zygomycosis or phycomycosis. Zygomycetes commonly infect patients suffering from immunosuppression, leukemia, lymphoma, extensive burns, acidosis, etc.. These molds invade blood vessels and proliferate in the walls, leading to thrombosis. Histopathological examination of the tissue reveals presence of broad, nonseptate, and irregular hyphae in thrombosed vessels or sinuses. Zygomycetes reproduce asexually to produce sporangia that bear sporangiospores.
Rhizoids arise at the base of unbranched sporangiophores of Rhizopus. Sporangiophores are long and dark with black round sporangia containing 1-celled, unbranched, globose sporangiophores. Absidia is characterized by presence of rhizoids that originate between sporangiophores. Sporangiophores bears pear shaped sporangia made up of 1-celled round sporangiospores. Mucor does not contain rhizoids, and simple or branching Sporangiophores arise from hyphae. Sporangia are round and contain 1-celled sporangiospores. Candida albicans is the normal flora of the human body that can cause a variety of infections when the normal host defense is compromised. It produces hyphae and pseudohyphae on cornmeal agar. The microscopic examination of the colony on the slide culture reveals the presence of pseudohyphae with blastoconidia at the nodes and thick walled chlamydospores at the terminals. Candida albicans is also positive for germ tube production.

Question 36

Which of the following is a zygomycete that lacks rhizoids or stolons and is characterized by the presence of sporangiophores that bears a round sporangium filled with sporangiospores?

1 Absidia
2 Mucor
3 Rhizopus
4 Candida albicans
5 Aspergillus fumigatus

Answer 36

Mucor

Aspergillus fumigatus is commonly associated with infection in immunocompromised patients and is also implicated in invasive aspergillosis. Culture of Aspergillus fumigatus appears blue green to gray green and microscopic examination of the colonies reveals septate hyphae giving rise to conidiophores with vesicle bearing uniseriate phialids. Aspergillus fumigatus can tolerate the temperature of >45°C. Absidia, Mucor, and Rhizopus are the molds that belong to class Zygomycetes and are associated with opportunistic infection known as zygomycosis or phycomycosis. Zygomycetes commonly infect patients suffering from immunosuppression, leukemia, lymphoma, extensive burns, acidosis, etc.. These molds invade blood vessels and proliferate in the walls, leading to thrombosis. Histopathological examination of the tissue reveals presence of broad, nonseptate, and irregular hyphae in thrombosed vessels or sinuses. Zygomycetes reproduce asexually to produce sporangia that bear sporangiospores.
Rhizoids arise at the base of unbranched sporangiophores of Rhizopus. Sporangiophores are long and dark with black round sporangia containing 1-celled, unbranched, globose sporangiophores. Absidia is characterized by presence of rhizoids that originate between sporangiophores. Sporangiophores bears pear shaped sporangia made up of 1-celled round sporangiospores. Mucor does not contain rhizoids, and simple or branching Sporangiophores arise from hyphae. Sporangia are round and contain 1-celled sporangiospores. Candida albicans is the normal flora of the human body that can cause a variety of infections when the normal host defense is compromised. It produces hyphae and pseudohyphae on cornmeal agar. The microscopic examination of the colony on the slide culture reveals the presence of pseudohyphae with blastoconidia at the nodes and thick walled chlamydospores at the terminals. Candida albicans is also positive for germ tube production.

Question 37

Which of the following is a zygomycete characterized by the presence of rhizoids that originates between sporangiophores?

1 Absidia
2 Mucor
3 Rhizopus
4 Candida albicans
5 Aspergillus fumigatus

Answer 37

Absidia

Aspergillus fumigatus is commonly associated with infection in immunocompromised patients and is also implicated in invasive aspergillosis. Culture of Aspergillus fumigatus appears blue green to gray green and microscopic examination of the colonies reveals septate hyphae giving rise to conidiophores with vesicle bearing uniseriate phialids. Aspergillus fumigatus can tolerate the temperature of >45°C. Absidia, Mucor, and Rhizopus are the molds that belong to class Zygomycetes and are associated with opportunistic infection known as zygomycosis or phycomycosis. Zygomycetes commonly infect patients suffering from immunosuppression, leukemia, lymphoma, extensive burns, acidosis, etc.. These molds invade blood vessels and proliferate in the walls, leading to thrombosis. Histopathological examination of the tissue reveals presence of broad, nonseptate, and irregular hyphae in thrombosed vessels or sinuses. Zygomycetes reproduce asexually to produce sporangia that bear sporangiospores.
Rhizoids arise at the base of unbranched sporangiophores of Rhizopus. Sporangiophores are long and dark with black round sporangia containing 1-celled, unbranched, globose sporangiophores. Absidia is characterized by presence of rhizoids that originate between sporangiophores. Sporangiophores bears pear shaped sporangia made up of 1-celled round sporangiospores. Mucor does not contain rhizoids, and simple or branching Sporangiophores arise from hyphae. Sporangia are round and contain 1-celled sporangiospores. Candida albicans is the normal flora of the human body that can cause a variety of infections when the normal host defense is compromised. It produces hyphae and pseudohyphae on cornmeal agar. The microscopic examination of the colony on the slide culture reveals the presence of pseudohyphae with blastoconidia at the nodes and thick walled chlamydospores at the terminals. Candida albicans is also positive for germ tube production.

Question 38

A previously healthy 47-year-old factory worker from Mississippi River Valley is admitted to the hospital with pneumonia. He usually works in a dusty environment and sweeps the factory. He has a 2-week history of productive cough, fever, chills, weight loss, and night sweats. His chest radiograph shows patches of bronchopneumonic disease. His white cell count is 9,000. His sputum gram stain is not helpful to the diagnosis, and the acid-fast stain is also negative. What organism is the most likely cause?

1 Mycobacterium tuberculosis
2 Pneumococcus pneumoniae
3 Blastomyces dermatitidis
4 Pneumocystis carinii
5 Mycoplasma pneumoniae

Answer 38

Blastomyces dermatitidis

In this case, there are clues suggesting blastomycosis, such as the location, dust exposure, and insidious onset. Blastomycosis is an infectious disease caused by Blastomyces dermatitidis, primarily involving the lungs and skin. Occasionally, it spreads hematogenously. Cutaneous lesions may be primary (usually self-limiting) or secondary as a manifestation of systemic disease. Pulmonary infections often present with dry or productive cough, fever, weight loss, night sweats, and gradually deteriorates. The clinical picture must be distinguished from Tb, other fungus infections, and bronchogenic carcinoma. Most reported cases are from North America, mainly southwestern states and the Mississippi River Valley. B. Dermatitidis can be isolated from soil that contains organic debris. People collecting firewood, tearing down buildings, or exposed to the dust from soil or other outdoor activities are at risk of infection.
Mycobacterium tuberculosis may be excluded from options by negative acid-fast stain of sputum; nevertheless, the cultures should be taken for Tb.
This is not a typical presentation for P. pneumoniae, which presents as lobar pneumonia and a sudden onset with fever..
P. Carinii is an opportunistic infection often seen in HIV positive patients or immunodeficient patients. This patient was previously healthy.
M. Pneumoniae causes atypical pneumonia. It is a possibility with bronchopneumonic changes and insidious onset, but usually its cough is not productive and weight loss is not a feature. Most of the cases are self-limiting and rarely need hospitalization. In this case, the patient’s location is given as a clue and the occupational exposure is important. Among these choices, B. dermatitidis will be the best answer.

Question 39

A 26-year-old man comes to your office with an itchy rash in his groin since a couple of weeks ago. He says the rash is getting worse with the summer months and after jogging it gets especially itchy. The rash is a scaly, red, map-like lesion and it is extending from the groin to the inner thighs on both sides. What is the most likely name of this condition?
Answer Choices

1 Tinea corporis
2 Tinea pedis
3 Tinea unguium
4 Tinea capitis
5 Tinea cruris
6 Tinea barbae

Answer 39

Tinea cruris

Dermatophytes are cutaneous mycoses. These infections are named according to the sites involved. The classic manifestation is generally designated ringworm (tinea) and named as follows:
Tinea corporis: ringworm of the body.
Tinea pedis: ringworm of the feet; athlete’s foot.
Tinea unguium: ringworm of the nails; also called onychomycosis.
Tinea capitis: ringworm of the scalp; mainly affects children.
Tinea cruris: ringworm of the groin, perineum, or perianal area; also called jock itch, more common in males.
Tinea barbae: ringworm of the bearded areas of the face and neck; is rare.

Question 40

A 26-year-old man comes to your office with an itchy rash in his groin for a couple of weeks. He says the rash is getting worse with the summer months and after jogging, it especially gets very itchy. The rash is scaly, red, and a map like lesion and it is extending from the groin to the inner thighs on both sides. Which of the following organisms is the most likely cause?

1 Dermatophytes
2 Staphylococcus aureus
3 Corynebacterium minutissimum
4 Malassezia furfur
5 Madurella mycetomatis

Answer 40

Dermatophytes

This case is a typical presentation of Tinea cruris, or also called “jock itch”. It is a common cutaneous mycoses, more in males, and more common in summer months. Humidity, heat, and tight clothing tends to favor growth of the organism. Dermatophytoses (tinea, ringworm) are caused by fungi (dermatophytes) that infect only superficial keratinized structures such as skin, hair and nail, but not deeper tissues.
The most important dermatophytes are:
Trichophyton: infects skin, hair and nails
Microsporum: infects skin and hair but not nails.
Epidermophyton: infects skin and nails but not hair.
Staphylococcus aureus is a common cause of folliculitis, furuncles and carbuncles.
Corynebacterium minutissimum causes superficial skin infections called erythrasma. It is found most commonly in adults with a higher incidence in the tropics and in diabetics. It may resemble a chronic fungal infection, involving the toe webs.
Malassezia furfur is the etiologic agent of Tinea vesicolor, a fungal infection characterized by blotchy depigmentation and itchiness mainly involving the skin of the upper chest and back.
Madurella mycetomatis is one of the etiologic agents of mycetoma, which is characterized by swelling, abscess, and sinus formation of subcutaneous tissues.

Question 41

A 26-year-old man comes to your office with an itchy rash in his groin for a couple of weeks. He says the rash is getting worse with the summer months and after jogging, it especially gets very itchy. The rash is scaly, red, and a map like lesion and it is extending from the groin to the inner thighs on both sides. He also has red lesions on his hands that started at the same time as the groin lesions. Which of the following best describes the hand lesions?

1 Tinea corporis
2 Tinea unguium
3 Tinea carpalis
4 Secondary syphilis rash
5 Dermatophytid (id) reaction

Answer 41

Dermatophytid (id) reaction

Patients infected with dermatophytes may show atypical cutaneous lesions, often on the hands, from which no fungi can be recovered or demonstrated. These lesions are secondary to immunologic sensitization to a primary (often unnoticed) infection located somewhere else. These secondary lesions will not respond to topical treatment but will disappear if the primary infection is successfully treated. Tinea corporis is the ringworm of the body. Tinea unguium is the ringworm of the nails. Tinea carpalis is not a medical name, there is no known infection with this name. Secondary syphilitic rash may also involve the palms, also soles of the feet and the body, but usually people don’t have a primary ringworm infection, and syphilis rash remains the same without changing for couple of weeks and disappears by itself without treatment.

Question 42

What is the best initial treatment for this condition?

1 Fluconazole
2 Praziquantel
3 Amphotericin-B
4 Clotrimazole
5 Itraconazole

Answer 42

Clotrimazole

This man has typical presentation of Tinea cruris, dermatophytoses (ringworm) of the groin area. Topical therapy is usually successful and the initial choice for treating dermatophytoses infections. The only topical antifungal here is clotrimazole; all of the others cannot be used topically. The other antifungal topicals, which can also be used, are tolnaftate, miconazole, and ketoconazole.
For resistant cases or those with very widespread involvement, systemic therapy is indicated. Griseofulvin is a widely used systemic antifungal agent and is effective in treating tinea capitis, corporis, pedis, cruris, and unguium. Tinea unguium requires long-term treatment, and fluconazole and itraconazole are also used successfully. Tinea vesicular can be treated with ketoconazole; griseofulvin is not effective in treating tinea vesicular. Amphotericin B is a parenteral antifungal; it is used for systemic, subcutaneous, deep mycoses, and opportunistic infections in immunocompromised patients. Praziquantel is an antiparasitic drug.

Question 43

What is the most likely diagnosis in this case?

1 Cytomegalovirus encephalitis
2 Cryptococcal meningitis
3 Tuberculous meningitis
4 Cerebral aspergillosis
5 Cerebral toxoplasmosis

Answer 43

Cryptococcal meningitis

The patient in this case is immunocompromised due to the immuno-suppressive therapy and is prone to opportunistic infections. Cryptococcal meningitis is caused by the fungus Cryptococcus neoformans. It occurs with increasing frequency in association with AIDS and may be fulminant and fatal in as little as 2 weeks, or it may be indolent, evolving over months or years. The mucoid encapsulated yeasts can be visualized in the CSF by India ink preparation. The brain shows chronic meningitis affecting the basal leptomeninges which are opaque and thickened. Sections of the brain disclose a gelatinous material within the sub-arachnoid space and small cysts within the parenchyma. Parenchymal lesions consist of aggregates of organism within the expanded peri-vascular spaces associated with minimal or absent of inflammation or gliosis. The meningeal infiltrates consists of chronic inflammatory cells, fibroblasts admixed with cryptococci, which can be seen well with PAS, mucicarmine or silver stain.
Cytomegalovirus causes typically sub-acute encephalitis in immuno-suppressed patients. Although any type of cell in the CNS can be infected by CMV, there is a tendency for the virus to localize in the ependymal and sub-ependymal regions of the brain causing severe hemorrhagic necrotizing encephalitis and choroid plexitis. Prominent cytomegalic cells with intranuclear and intracytoplasmic inclusions can be readily identified by conventional light microscopy, immunocytochemistry, or in-situ hybridization.
Infection by Mycobacterium tuberculosis in immuno-suppressed patients is similar to that in immuno-competent patients but they can also be infected by Mycobacterium avium intracellulare. In tubercular meningitis, there is moderate pleocytosis made up of mononuclear cells or a mixture of polymorphs and mononuclear cells, the protein level is elevated and glucose content is moderately reduced or normal. On macroscopy, the subarachnoid space contains gelatinous or fibrinous exudates, most often at the base of the brain, obliterating the cisterns and encasing the cranial nerves. There may be discrete white granules scattered over the leptomeninges. On microscopy, there is a mixture of lymphocytes, plasma cells, macrophages, and well-formed epithelioid granulomas with Langerhans giant cells. Organisms can often be seen with acid-fast stain.
Fungal disease of the CNS is encountered primarily in immuno-compromised patients. Aspergillosis and mucormycosis has marked predilection for invasion of blood vessel walls causing thrombosis producing hemorrhagic infarction with subsequent ingrowth of the fungus. Cerebrospinal fluid examination will not be of any diagnostic value. Numerous septate hyphae invading blood vessels with acute inflammatory reaction can be seen in tissue sections.
Cerebral toxoplasmosis is caused by the protozoa Toxoplasma gondii. In immunocompetent patients, most infections are asymptomatic or self-limiting. Congential toxoplasmosis occurs following primary maternal infection early in the pregnancy causing cerebritis in the fetus with production of multi-focal cerebral necrotizing lesion that may calcify producing severe damage to the brain. Infection with T. gondii is one of the most common causes of neurological symptoms and morbidity in patients with AIDS. CT and MRI show multiple ring enhancing lesions. The brain shows multiple abscesses often involving the cerebral cortex. Acute lesions consist of central foci of necrosis with variable petechiae surrounded by acute and chronic inflammation, macrophage infiltration, and vascular proliferation. Both the tachyzoites and encysted bradyzoites may be found at the periphery of necrotic foci. The organisms are usually seen by routine H& E and Giemsa stains, but can be readily recognized by immunocytochemical methods.
Tuberculous meningitis
Cryptococcal meningitis
Toxoplasma encephalitis
CMV meningo-encephalitis
CSF cell count
100-500
leucocytes/cum
Normal/moderate
Pleocytosis
Normal/Moderate
pleocytosis
50-500 leucocytes/cum
Cell type Predominantly
lymphocytes Predominantly lymphocytes Lymphocytes Predominantly
lymphocytes
CSF protein Increased (100
-500 mg/dl)
Increased or Normal Normal/ Increased
Increased but rarely above 200mgs/dl
CSF glucose Decreased or Normal Decreased or Normal Normal or decreased Normal
Diagnostic test AFB positive in CSF in 1/3rd of the patients India ink preparation positive in the CSF of the affected patients Cryptococcal polysaccharide antigen detectable in CSF Tachyzoites or brady cysts are seen in the tissue sections by routine H&E/Giemsa stains or by immunohistological stain. Prominent cytomegalic cells with nuclear and cytoplasmic inclusion seen in the tissue sections

Question 44

The etiological agent of the infection most likely belongs to what genera?

1 Rhodotorula
2 Candida
3 Tricosporon
4 Malassezia
5 Tricosporon

Answer 44

Candida

A prolonged indwelling vascular catheter is an important predisposing factor for nosocomial opportunistic bloodstream infections.
Gram-positive oval budding cells in the blood culture smears indicate yeast forms. Fungi that belong to all the genera listed have yeast forms. Candida species are urease-negative yeasts. The tests for Chlamydospore formation and germ tube production are done when a yeast is identified as Candida species. These tests help to differentiate Candida albicans from other species of Candida. After incubation in serum at 37°C for 90 minutes, yeast cells of C.albicans will begin to form germ tubes. On nutritionally deficient media, C.albicans produces large spherical chlamydospores. Negative germ tube and chlamydospore tests help to rule out Candida albicans; therefore, the fungal agent that caused the outbreak is most likely to be a non-albicans Candida species and belongs to the genus Candida.
Candida sp is one of the most common agents of nosocomial invasive fungal infections. In recent decades, it has emerged as the 4th most common cause of nosocomial bloodstream infections worldwide. Prevalence of nosocomial bloodstream infections due to non-albicans candida species resistant to fluconazole is reported to be on the increase. C.glabrata, C.parapsilosis, C.tropicalis, and C.krusei are species that show varying degrees of fluconazole resistance and are associated with bloodstream infections.
Newer broad-spectrum azoles, echinocandins, and amphotericin B are found useful for the treatment of infections by fluconazole-resistant species.
Biofilm formation by Candida sp on the surface of intravascular devices may result in increased resistance to antifungal agents and protection of the fungus from host defenses.
Other genera listed can be excluded due to a number of reasons. Rhodotorula and tricosporon are urease-positive yeasts. They have occasionally been associated with bloodstream infections. The negative urease test excludes these fungi.
All penicillium species except P. marneffi are molds. P.marneffi, a significant pathogen associated with AIDS in Southeast Asia, is dimorphic and appears as uninucleated yeast forms at 37°C. The yeast forms reproduce by fission and not by budding, and the cells show distinct central septum.
Malassezia are lipophilic yeasts. Media containing an overlay with sterile oil are used for culturing malassezia, as they are not readily isolated in conventional media.
Species that are part of normal flora of skin like M.furfur have been associated with dermatological diseases. Catheter-associated bloodstream infections caused by malassezia are very rare. Such infections occurring in neonatal ICUs have been documented, involving neonates on prolonged use of indwelling catheters and who are receiving lipid formulations.

Question 45

What is the most likely diagnosis?

1 Hairy leukoplakia
2 Atrophic glossitis
3 Hairy tongue
4 Geographic tongue
5 Candidiasis

Answer 45

Candidiasis

Candidiasis is an infection that may cause the tongue to have a white coating. This coating can be scraped and a sample can be analyzed for the presence of Candida.
Hairy leukoplakia may be seen in people infected with HIV and AIDS. It is characterized by raised areas that are whitish-tan in color and have a feathery appearance. Hairy leukoplakia cannot be scraped off.
A “hairy tongue” is not actually due to hair growth on the tongue; it consists of elongated papillae that have the appearance of grayish-black hair to the naked eye. This condition may be caused by antibiotic use, or there may not be any reason.
Atrophic glossitis (or smooth tongue) presents as having a smooth surface due to papillae loss. The loss may indicate deficiency in riboflavin, niacin, folic acid, vitamin B12, pyridoxine, or iron.
A geographic tongue is a benign condition with unknown cause; it is characterized by a map-like pattern of smooth, red areas that do not have papillae as well as rough areas that still have papillae.

Question 46

What is the most likely diagnosis?

1 Aspergillosis
2 Blastomycosis
3 Candidiasis
4 Coccidioidomycosis
5 Cryptococcosis

Answer 46

Coccidioidomycosis

The only dimorphic fungal infection that is endemic in the specified regions listed and that produces large spherule forms containing endospores in infected tissues is Coccidioidomycosis.
Primary infection occurs mainly by inhalation of airborne arthrospores of the fungus from soil sites. After entering the host tissues, each arthrospore develops into a multi-nucleated spherule. The spherule grows and divides, internally producing uninucleated endospores. The mature thick-walled spherule measures 60-100 microns and endospores are 2-5 microns in size. Endospores are liberated by rupture of mature spherules and in the tissue; each endospore further develops into a spherule. The spherules and endospores are seen within the granulomatous lesions of coccidioidomycosis.
Aspergillosis is a fungal infection that also affects the lung and resembles an acute inflammatory/allergic response. The disease is especially dangerous for patients who are immunocompromised. Samples of lung tissue produce characteristic conidial structures including septate hyphae.
Blastomycosis is a dimorphic fungus that causes a lung infection that ranges from mild to more severe chronic pneumonia and the presence of noncaseating granulomas. Examination of infected tissue may reveal septate hyphae as well as characteristic budding yeast.
Candidiasis is a common yeast that may produce various types illnesses, from oral and vaginal infections to systemic infection. The characteristic feature is the presence of “pseudohyphae” and budding yeast.
Cryptococcosis is a yeast that may affect several tissues including the lung. It is found worldwide, notably in pigeon droppings. Its characteristic feature is a prominent capsule that can be visualized on Giesma stain of infected tissue.

Question 47

What is the most likely causative agent?

1 Tinea corporis
2 Tinea barbae
3 Tinea capitis
4 Tinea unguim
5 Candida albicans

Answer 47

Tinea corporis

The clinical presentation of the skin lesions is suggestive of tinea corporis, a manifestation of a fungal infection that affects the skin. Characteristic symptoms include itching and annular lesions with a ring-border. Scaling is also typical.
Tinea barbae and tinea capitis are fungal infections that affect the hair and scalp.
Tinea unguim is a fungal infection that affects the nails.
Candida albicans is a yeast infection that commonly occurs in moist areas such as the intergluteal, scrotal, vaginal, and axillary regions. It typically causes itching and redness with satellite papules and pustules. Annular lesions and scaling are not characteristic of this infection.

Question 48

What is the most likely diagnosis?

1 Tinea corporis
2 Tinea versicolor
3 Tinea capitis
4 Tinea unguim
5 Candida albicans

Answer 48

Tinea capitis

The clinical presentation of the skin lesions is suggestive of tinea capitis, a manifestation of a fungal infection that affects the hair and scalp. The classic presentation is an annular lesion with central clearing and scaling. The condition also causes itching. This is a fairly common infection in young children.
Tinea corporis is the same fungal infection; however, it presents on the skin rather than the scalp. It causes red, annular lesions with scaling.
Tinea versicolor is a yeast infection that presents with a patchy area of hypo- and hyper-pigmented skin. It resembles vitiligo.
Tinea unguim is a fungal infection that affects the nails.
Candida albicans is a yeast infection that commonly occurs in moist areas such as the intergluteal, scrotal, vaginal and axillary regions. It typically causes itching and redness with satellite papules and pustules. Annular lesions and scaling are not characteristic of this infection.