Medical Mycology (Habal)

Question 1

What fungus causes tinea corporis/cruris/pedis/capitis/unguium/manus? Clinical presentation: invasion of keratinized structures with possible secondary bacterial infections and mild inflammatory response in infected areas.

Answer 1

Dermatophytes

Question 2

What fungus causes soft, pale nodules on hair in groin and axilla?

Answer 2

White Piedra - Tienea blanca, Trichosporon beigelii

Question 3

What fungus causes and small, dark nodules on hair shaft)?

Answer 3

Black Piedra - Piedra hortae

Question 4

What fungus causes Pityriasis versicolor - hypopigmented spots on chest, back, arms, shoulders, face, or neck? May also occur in lipid-dependent yeast in young adults with oily skin.

Answer 4

Malassezia furfur

Question 5

What fungus causes Sporotrichoses (Rose Gardener’s Disease) - local pustules and ulcers with nodules at site of infection and along draining lymphatics? May also spread secondarily to articular surfaces, bone, and muscle.

Answer 5

Sporothrix schenckii

Question 6

What may happen to the immunocompromised if they are infected by Sporothrix schenckii?

Answer 6

Fungus (Sporothrix schenckii) may become disseminated.

Question 7

What fungus causes the “Summer Flu” of the Midwest?

Answer 7

Histoplasma capsulatum

Question 8

What fungus may affect the spleen, liver, and bone marrow; is often asymptomatic, may resemble TB pneumonia as progressive lung disease, may cause ocular histoplasmosis, and disseminates in immunocompromised patients?

Answer 8

Histoplasma capsulatum

Question 9

What fungus causes “Chicago Disease”; fever, night sweats & weight loss; pulmonary stage which may be followed by chronic granulomatous stage (lung & skin granuloma may ulcerate), and may affect the spine, pelvis, cranial bones, and ribs?

Answer 9

Blastomyces dermatitidis

Question 10

What fungus causes “San Joaquin Valley Feve”; fever, productive cough, chest pain, extreme fatigue (usually self-limited), erythema multiforme & granulomas called Desert Bumps, is often associated with anorexia, and has symptoms that appear 7-28 days after exposure?

Answer 10

Coccidioides immitis

Question 11

What fungus causes disease of the lungs and skin that rarely becomes systemic?

Answer 11

Paracoccidiodes brasiliensis

Question 12

What fungus causes lung injury and meningioencephalitis (fever, loss of vision, stiff neck, mental status change, possibly hydrocephalus)?

Answer 12

Cryptococcus neoformans

Question 13

What fungus causes infection ranging from mild (diaper rash) to fatal (systemic)? Name this infection.

Answer 13

Candida species - Candidiasis

Question 14

What fungus causes vulvovaginitis, cutaneous candidiasis, oral thrush, esophageal candidiasis, and disseminated candidiasis?

Answer 14

Candida albicans

Question 15

What is an AIDS-defining illness caused by a fungus? (Name the fungus as well.)

Answer 15

Esophageal candidiasis - Candida albicans

Question 16

What fungus causes mycotoxicosis - ingestion of contaminated foods, possible precursor to liver cancer?

Answer 16

Aspergillus fumigatus

Question 17

What fungus causes allergy/sequelae to presence of conidia or transient growth of organism in body orifices; colonization without extension in preformed cavities and debilitated tissues, and invasive, inflammatory granulomatous disease of lungs and other organs?

Answer 17

Aspergillus fumigatus

Question 18

What fungus causes mold growth on organic material, such as bread?

Answer 18

Zygomycosis

Question 19

What fungus causes large clots that lead to infarctions & pneumonia; has no boundaries, causes headache & orbital cellulites, leads to cerebral nerve palsy, hemorrhage, coma, and death if not treated?

Answer 19

Zygomycosis - Mucor or Rhizopus

Question 20

What fungus causes bilateral infiltrate in lungs, fever, non-productive cough, breathing difficulty, respiratory failure, cyanosis, death by asphyxia, and rarely, extrapulmonary disease? 100% fatal if untreated.

Answer 20

Pneumocystis jiroveci

Question 21

What is the most common fungal cause of pneumonia?

Answer 21

Pneumocystis jiroveci

Question 22

What fungus can cause disease at sites distant to local infection and severe GE disease similar to cryptosporidiosis in AIDS?

Answer 22

Microsporidiosis

Question 23

Which fungi cause superficial infections?

Answer 23

Piedras, Dermatophytes, Malassezia furfur

Question 24

Which fungus causes subcutaneous infections?

Answer 24

Sporothrix schenckii

Question 25

Which fungi cause systemic fungal infections?

Answer 25

Histoplasma capsulatum, Blastomyces dermatitidis, Coccidiodes immitis, Paracoccidiodes brasiliensis

Question 26

Which fungi are opportunistic mycoses?

Answer 26

Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Mucor rhizopus, Pneumocystis jiroveci

Question 27

What do fungi release and why?

Answer 27

Release enzymes to degrade the environment for nutritive purposes.

Question 28

Fungi exist in what type of form? What does this mean?

Answer 28

They are thermally dimorphic - can exist in different forms, yeast or mold, depending on temperature.

Question 29

What are the 4 components of fungal structure?

Answer 29

Polysaccharide capsule, cell wall, cell membrane, cytoplasm

Question 30

What is the only encapsulated fungus we're discussing?

Answer 30

Cryptococcus neoformans

Question 31

Describe the cell membrane of fungi.

Answer 31

Similar to eukaryotic cell membrane - bilayered, made up of phospholipids and sterols, the latter of which is very important as some organisms need nutrients in order to synthesize them.

Question 32

Describe yeast.

Answer 32

Unicellular, asexual budding reproduction, sexual reproduction, may contain capsule (identified via India ink), aerobic, grows at wide range of temperatures (optimum at room temp)

Question 33

Describe mold.

Answer 33

Aerobic, filamentous, multicellular, spore/conidia reproduction, filaments known as hyphae (collection = mycelium, collection of these = mycelia, collection of these = mold

Question 34

What is a defining characteristic of hyphae? What is the name for this, and is it characteristic of all mold?

Answer 34

Fenestrated septate - separations in hyphae that allow for transfers of material between compartments. Not all hyphae have these; they're known as unseptate hyphae.

Question 35

What is pseudohyphae?

Answer 35

Lack of cytoplasmic connections between cells - see constriction in middle.

Question 36

Which fungus is pseudohyphae?

Answer 36

Candida

Question 37

What is a germ tube?

Answer 37

Hyphae sticking out of a spore. This is a virulence factor that is very invasive when systemic.

Question 38

What does fungal pathogenesis ultimately depend upon? What else?

Answer 38

Transmission is #1, but also depends on immune response.

Question 39

How are most fungal infections transmitted?

Answer 39

Via the environment.

Question 40

Which fungi are transmitted via human-human contact?

Answer 40

Dermatophytes

Question 41

What are the 3 main ways to ID fungus in a lab?

Answer 41

Sabouraud's agar, blood agar, microscopy

Question 42

How many fungi appear as hyphae in the body?

Answer 42

2

Question 43

In what form do most fungi present in the body?

Answer 43

yeast

Question 44

Describe superficial mycoses.

Answer 44

Confined to stratum corneum or distal portions of hair, mostly cosmetic, generally have no cellular response from host, and essentially elicit no pathological changes.

Question 45

What fungus invades keratinized structures and may cause secondary bacterial infections and mild inflammatory response in affected areas?

Answer 45

Dermatophytes

Question 46

How do you diagnose dermatophytes?

Answer 46

Branched hyphae on KOH wet mount or culture using either myobiotic agar or Sabouraud's dextrose agar

Question 47

What are the 3 types of dermatophytes, and which one is associated with humans?

Answer 47

Anthrophilic - person-to-person or fomite transmission, geopilic, zoophilic

Question 48

What genera make up dermatophytes?

Answer 48

Microsporum, Epidermophyton, Trichophyton

Question 49

Lab results show branched hyphae resembling spaghetti & meatballs shape. Yeast is spherical on KOH mount. Which fungus is this.

Answer 49

Malassezia furfur

Question 50

What is the name of the manifestion of infection caused by a group of fungi called black mold?

Answer 50

Mycetoma

Question 51

How are subcutaneous fungi transmitted?

Answer 51

Cut/abrasion/etc. allows traumatically inoculated spores to enter body, where they can then go into the lymphatic system. Macrophages can't do anything to them, so you get granulomas.

Question 52

What fungus are you likely to see world-wide, but more often in tropical areas?

Answer 52

Sporothrix schenckii

Question 53

Describe the morphology of Sporothrix schenckii.

Answer 53

Grows as mold (hyphae) in soil and switches to yeast in human host.

Question 54

What is the transmission of Sporothrix schenckii?

Answer 54

Traumatic implantation

Question 55

What is the most common form of candida?

Answer 55

Oral thrush

Question 56

Why are fungal infections a concern for obese patients?

Answer 56

Many skin folds make attractive warm, moist, and humid regions for fungi.

Question 57

Which fungus can be spread via person-to-person contact?

Answer 57

Candida albicans

Question 58

How are all systemic mycoses transmitted?

Answer 58

Via inhalation - lungs are the first site of interaction between fungus and immune cells. Spores turn to yeast in lower lobes; macrophages phagocytose yeast.

Question 59

Budding single-cell organisms are which fungi?

Answer 59

Systemic mycoses - Histoplasma capsulatum, Blastomyces dermatitidis, Coccidiomeds immitis, Paracoccidiodes brasiliensis

Question 60

Where can you find Histoplasma capsulatum?

Answer 60

Ohio-Mississippi River Valley

Question 61

Which fungus loves nitrogenous waste found in soil?

Answer 61

Histoplasma capsulatum

Question 62

Which fungus is seen often in caves, can be caught from spelunking, and is found in bat, pigeon, and chicken droppings?

Answer 62

Histoplasma capsulatum

Question 63

Using KOH and Parker Ink, you see single-cell yeast that buds with a narrow base. Definitive diagnosis shows the organism to be positive for H-antigen. What is this?

Answer 63

Histoplasma capsulatum

Question 64

What medium do you use to diagnose Histoplasm capsulatum?

Answer 64

Sabouraud's dextrose agar, supplemented with 5% sheep blood

Question 65

Which fungus would you most likely be infected with if you were East of the Mississippi River Valley or in Central America?

Answer 65

Blastomyces dermatitidis

Question 66

Which fungus is round with a refractive wall and a single broad-based bud? Definitive diagnosis shows the organism to be positive for Exo-A-antigen.

Answer 66

Blastomyces dermatitidis

Question 67

What fungus loves organic debris, such as soil, rotten wood, and beaver dams?

Answer 67

Blastomyces dermatitidis

Question 68

Which fungus would you most likely be infected with if you were in the SW US, specificially in the San Joaquin Valley or Arizona?

Answer 68

Cocciodiodes immitis

Question 69

Which fungus produces spherules?

Answer 69

Coccidiodes immitis

Question 70

What is a spherule?

Answer 70

Sac holding endospores that sporulate and give yeast after being inhaled into lungs.

Question 71

Which is the most virulent systemic mycoses, Histoplasma, Blastomyces, or Coccidiodes? Why?

Answer 71

Coccidiodes - inhalation of spherules

Question 72

What happens when you inhale Coccidiodes?

Answer 72

Inhale spherules that settle in the upper respiratory tract, and produce flu-like symptoms, followed by granulomas, which can become skin granulomas.

Question 73

What fungus are you likely to encounter in rural Latin America?

Answer 73

Paracoccidiodes brasiliensis

Question 74

You encounter a single-cell yeast that exhibits multiple buds when budding - looks like a wheel with spokes on it. Which fungus is this?

Answer 74

Paracoccidiodes brasiliensis

Question 75

Which fungus loves to grow on bird droppings and is associated with opportunistic infection?

Answer 75

Cryptococcus neoformans

Question 76

Which fungus presents as a yeast only; does not have a relevant mold phase?

Answer 76

Cryptococcus neoformans

Question 77

How is Cryptococcus neoformans transmitted?

Answer 77

Through inhalation

Question 78

Which fungus is the only yeast to "phenol oxidase," neutralizing the epinephrine oxidase system out of CNS?

Answer 78

Cryptococcus neoformans

Question 79

Which fungus can be found as a budding yeast with an antiphagocytic polysaccharide capsule?

Answer 79

Cryptococcus neoformans

Question 80

Diagnosis is a positive CSF culture of a urease positive organism that can be seen using bird seed agar and India ink. What is it?

Answer 80

Cryptococcus neoformans

Question 81

What ubiquitous fungi is found throughout the world as normal body flora?

Answer 81

Candida species

Question 82

In what forms can the Candida species appear?

Answer 82

Yeast, psuedohyphae, true hyphae

Question 83

What kind of environment do Candida species require?

Answer 83

Slightly alkaline - pH of 7.4

Question 84

Where does Candida albicans present on the body?

Answer 84

Skin and mucous membranes

Question 85

What is a potential, threatening consequence of Candida albicans entering the body?

Answer 85

Endocarditis

Question 86

How do antibiotics affect fungi of normal body flora?

Answer 86

They change the pH - fungi will grow at an alkaline pH. This happens when lactobacilis is present.

Question 87

Axillae, groin, submammary folds, intergluteal fold, and interdigital spaces are common locations for what fungal infection?

Answer 87

Intertriginous candidiasis

Question 88

These fungal infections are often associated with use of broad spectrum antibiotics in women, pregnancy, low vaginal pH, diabetes, and poor hygiene. What are they?

Answer 88

Vulvovaginal candidiasis and balantitis

Question 89

Cloudy vision and lesions within the eye can be caused by what fungal infection that can be spread in the blood stream via indwelling catheters, IV drug abuse, and ocular trauma/surgery?

Answer 89

Ocular candidiasis

Question 90

Which fungus is infectious at low doses?

Answer 90

Aspergillus fumigatus

Question 91

Which fungus appears as a flowering sporangium with finger-like projections and V-shaped branching septate hyphae?

Answer 91

Aspergillus fumigatus

Question 92

Which fungus does not exist as yeast and thus does not exhibit thermal dimorphism?

Answer 92

Aspergillus fumigatus

Question 93

Which fungus will find an area/cavity to grow in lungs, where it will form a hyphae fungus ball?

Answer 93

Aspergillus fumigatus

Question 94

Some organisms will secrete some type of ercotoxin that has symptoms of convulsions and gangrene, which are associated with certain foods. What organism does this?

Answer 94

Aspergillus fumigatus

Question 95

What fungus does not exist as a yeast, but rather systematically as a non-spectate hyphae that branches at a right angle?

Answer 95

Zygomycosis (Mucormycosis)

Question 96

What fungus is associated with the immunocompromised and elderly?

Answer 96

Zygomycosis (Mucormycosis)

Question 97

Which fungus will you see in patients with uncontrolled diabetes who are nearing stages of acidosis?

Answer 97

Zygomycosis (Mucormycosis)

Question 98

Which fungus will begin growing in nasal sinuses, causing headaches?

Answer 98

Zygomycosis (Mucormycosis)

Question 99

Which fungus is associated with a high fatality rate for the immunocompromised and elderly?

Answer 99

Mucor/Rhiospus

Question 100

What is the new name for Pneumocystis carinii?

Answer 100

Pneumocystis jiroveci

Question 101

What is the cause of fungal pneumonia that is also an AIDS-defining illness?

Answer 101

Pneumocystis jiroveci

Question 102

Risk factors for infection of this fungus include: CD4 count<200 cells/micro-L, prior PCP infection, oral thrush, recurrent bacterial pneumonia, and HIV. What fungus is this?

Answer 102

Pneumocystis jiroveci

Question 103

The following are clinical signs and presentations of what disease: bilateral infiltrate in lungs (alveoli fill with foamy exudate containing organism), fever, non-productive cough, breathing difficulty on exertion/respiratory failure;cyanosis, death by asphyxia?

Answer 103

Pneumocystis jiroveci