Fungal infections Flashcards
(146 cards)
1
Q
What is the most common cause of fungal lymphangitis?
A
Sporothrix schenckii
2
Q
What is the most common cause of bacterial lymphangitis?
A
Group A Streptococcus is the most common cause of bacterial lymphangitis.
3
Q
What is Sporothrix schenckii and what disease does it cause?
A
Sporothrix schenckii is a dimorphic fungus that causes sporotrichosis, also known as rose gardener’s disease, found in soil, plants, and decaying organic matter. Commonly affects individuals exposed to vegetation (e.g., gardeners, landscapers).
Mold in the cold (25 - 30 C)
Yeast in the heat (35 - 37 C)
4
Q
Where is Sporothrix schenckii commonly found?
A
Found in soil, plant debris, tree bark, and bushes.
Associated with rose thorns and other contaminated plant materials.
5
Q
How does Sporothrix schenckii enter the body?
A
Through physical trauma, such as a puncture wound from a thorn or contaminated material. Infection often occurs after handling plants contaminated with Sporothrix schenckii, such as being pricked by rose thorns.
6
Q
What are the characteristic microscopic features of Sporothrix schenckii in its yeast form?
A
Cigar-shaped cells are seen microscopically in its yeast form. Initial nodule forms at the site of inoculation. Subsequent painless nodules and ulcerations develop along lymphatic channels.
Can be visualized with methanemine silver.
7
Q
What is the pattern of lesion spread in lymphocutaneous sporotrichosis?
A
Lesions spread in an ascending pattern along the lymphatic channels.
Start as local pustules or ulcers, progressing to subcutaneous nodules.
8
Q
What is the gold standard for diagnosing sporotrichosis?
A
Culture of the organism.
Confirmed by fungal culture from lesion biopsy or exudate.
Biopsy showing granulomas with histiocytes, multinucleated giant cells, and yeast cells is also diagnostic. Histopathology shows cigar-shaped yeast in tissues.
9
Q
What is the preferred treatment for sporotrichosis?
A
PO Itraconazole is the first-line treatment for cutaneous and lymphocutaneous sporotrichosis.
Severe/disseminated cases: Amphotericin B.
Divine Intervention also says Bactrim (sulfamethoxazole and trimethoprim)
10
Q
What historical treatment is sometimes used for sporotrichosis?
A
Saturated solution of potassium iodide (SSKI), though modern antifungal medications are preferred.
11
Q
Where is Histoplasma capsulatum geographically endemic?
A
The Midwestern and Central United States, particularly along the Mississippi and Ohio River Valleys.
12
Q
How is Histoplasma capsulatum transmitted?
A
Inhalation of airborne fungal spores from soil or mold.
Often associated with bird droppings and bat guano.
13
Q
What type of individuals are at increased risk of histoplasmosis?
A
Most are asymptomatic.
Immunocompromised patients, such as those with HIV/AIDS or undergoing chemotherapy, are the people most at risk, as are individuals exposed to bird or bat droppings.
14
Q
What are the key clinical features of histoplasmosis?
A
Constitutional symptoms:
Fever, Fatigue, Malaise, weight loss
Pulmonary symptoms:
Cough, lung cavitations (resembles tuberculosis), patchy/nodular infiltrates, Hilar lymphadenopathy.
Disseminated disease:
Arthalgias, Hepatosplenomegaly, skin nodules, ulcers and other skin manifestations like erythema nodosum.
15
Q
What dermatologic finding is associated with histoplasmosis?
A
Erythema nodosum, characterized by painful red nodules on the shins.
16
Q
What is the role of lung calcifications in histoplasmosis?
A
Chronic histoplasmosis can lead to calcified mediastinal and hilar lymph nodes, as part of the healing process.
17
Q
What would pertinent lab findings show in a patient with histoplasmosis?
A
- Disseminated histoplasmosis can cause hepatosplenomegaly, pulmonary infiltrate, and papular skin lesions, the skin lesions do not typically have umbilication or central necrosis.
- Pancytopenia
- Elevated AST/ALT
- Elevated LDH
18
Q
What is the histological hallmark of Histoplasma capsulatum on microscopy?
A
Small intracellular oval yeast bodies within macrophages.
These yeast cells are smaller than red blood cells.
19
Q
What diagnostic tests are available for histoplasmosis?
A
Bone marrow aspiration is often required for diagnosis of disseminated histoplasmosis, which occurs far more commonly in patients with advanced HIV.
Antigen testing of serum or urine (SAg, UAg).
Tissue biopsy or respiratory specimen staining.
Culture is the gold standard.
20
Q
What is the treatment for mild histoplasmosis?
A
Itraconazole (an azole antifungal).
21
Q
What is the treatment for severe or disseminated histoplasmosis?
A
Amphotericin B is the drug of choice for severe cases, followed by itraconazole as step-down therapy.
22
Q
Where is Blastomyces dermatitidis geographically endemic?
A
Eastern and Central United States
Near the Ohio and Mississippi River Valleys
The Great Lakes region
23
Q
What is Blastomyces dermatitidis and what disease does it cause?
A
Blastomyces dermatitidis is a dimorphic fungus that causes blastomycosis, a systemic fungal infection.
24
Q
Which populations are at higher risk for disseminated blastomycosis?
A
Immunocompromised individuals, such as those with HIV/AIDS or undergoing chemotherapy.
Can disseminate even if immunocompetent.
25
How is Blastomyces dermatitidis transmitted?
Through inhalation of mold spores.
The spores convert to yeast form upon entering the lungs.
26
What are the common pulmonary manifestations of blastomycosis?
Known to cause acute and chronic pneumonia
Patchy alveolar infiltrates or "haziness" on chest X-rays (CXR).
May include mass-like lesions or cavitations.
Granulomatous infection, with the lungs being the most commonly affected organ.
27
What systemic organs are affected in disseminated blastomycosis?
Lungs (most common), skin, and bones.
Skin lesions: Papules, pustules, ulcers, or verrucous growths.
Bone involvement: Painful lytic lesions, osteomyelitis.
28
What is the characteristic morphology of Blastomyces dermatitidis in its yeast form?
Yeast form exhibits broad-based budding with a double refractile cell wall.
Similar in size to a red blood cell (RBC).
29
What diagnostic methods are used for blastomycosis?
Urine antigen test.
Microscopy, culture, or histopathology (gold standard).
30
What is the treatment for mild to moderate blastomycosis?
Itraconazole or fluconazole.
31
What is the treatment for severe or disseminated blastomycosis?
Amphotericin B is the drug of choice.
Followed by Itraconazole.
32
What is Coccidioides immitis, and what disease does it cause?
Coccidioides immitis is a dimorphic fungus that causes coccidioidomycosis, also known as San Joaquin Valley fever.
33
Where is Coccidioides immitis geographically endemic?
Southwestern United States (e.g., California, Arizona)
Northern Mexico
Found in desert soils.
34
How is Coccidioides immitis transmitted?
Through inhalation of airborne arthroconidia (mold spores).
Spores become airborne when soil is disturbed (e.g., farming, construction, earthquakes, or dust storms).
35
What is the characteristic morphology of Coccidioides immitis in tissue samples?
Appears as large yeast-like spherules containing endospores.
These spherules are larger than red blood cells (RBCs).
36
Which patients are at risk for disseminated coccidioidomycosis?
Immunocompromised patients, such as those with HIV/AIDS or undergoing immunosuppressive therapy.
37
What are the common clinical features of coccidioidomycosis?
Acute pneumonia: Cough, fever, chest pain, and arthralgia.
Erythema nodosum: Painful red nodules on the lower extremities.
In some cases, hilar lymphadenopathy and lung nodules or cavities.
38
What are the manifestations of disseminated coccidioidomycosis?
Systemic symptoms: fever, night sweats, weight loss.
Skin lesions: Papules, pustules, ulcers, verrucous growths.
Osteolytic bone lesions.
CNS involvement, such as meningitis.
39
What imaging findings are associated with primary coccidioidomycosis?
Unilateral infiltrates.
Hilar lymphadenopathy.
Nodules or cavities (though imaging may be normal in some cases).
40
How does Coccidioides immitis exhibit dimorphism?
Grows as mold in cooler environments (25–30°C).
Converts to yeast at human body temperature (35–37°C).
41
How is coccidioidomycosis diagnosed?
Serology using IgM
Cultures
42
What are the treatments for coccidioidomycosis?
Mild to moderate disease: Itraconazole or fluconazole.
Severe or disseminated disease: Amphotericin B, followed by Itraconazole.
43
What is Paracoccidioides brasiliensis, and what disease does it cause?
Paracoccidioides brasiliensis is a dimorphic fungus that causes paracoccidioidomycosis, a systemic fungal infection.
44
Where is Paracoccidioides brasiliensis geographically endemic?
Central and South America, particularly in Brazil.
45
What is the characteristic morphology of Paracoccidioides brasiliensis in its yeast form?
Multipolar budding radiating from a central cell, resembling a captain's wheel.
The yeast is larger than red blood cells (RBCs).
46
How is Paracoccidioides brasiliensis transmitted?
Through inhalation of mold spores.
47
What are the common clinical features of paracoccidioidomycosis?
Coughing and lymphadenopathy affecting cervical, axillary, and inguinal lymph nodes.
Granulomas in the lungs.
Mucosal ulcers in the upper respiratory tract.
48
Which organs are commonly affected in disseminated paracoccidioidomycosis?
Lungs, oral mucosa, and lymph nodes.
In severe cases, other organs may also be involved.
49
What are the treatments for paracoccidioidomycosis?
Mild to moderate disease: Azoles (e.g., itraconazole).
Severe disease: Amphotericin B.
50
What is Malassezia furfur, and what conditions does it cause?
Malassezia furfur is a fungus that is part of the normal skin flora.
Thrives in hot and humid conditions.
It causes pityriasis versicolor and seborrheic dermatitis.
51
How does Paracoccidioides brasiliensis exhibit dimorphism?
Grows as mold in cooler environments (25–30°C).
Converts to yeast at human body temperature (35–37°C).
52
How does Malassezia furfur appear on a KOH prep?
It has a characteristic "spaghetti and meatballs" appearance due to its yeast and hyphae forms.
53
What are the typical clinical features of pityriasis versicolor?
Hypopigmented or hyperpigmented macules or patches, often with fine scaling.
Commonly affects the back and chest.
Patches can merge into larger areas.
54
What environmental conditions favor the pathogenic form of Malassezia furfur?
Hot and humid conditions.
55
What layer of the skin does Malassezia furfur primarily infect?
The stratum corneum, the most superficial layer of the epidermis.
56
What systemic complication is associated with Malassezia furfur in neonates?
Malassezia fungemia, particularly in neonates receiving total parenteral nutrition (TPN) through central venous catheters.
57
What is the pathogenesis of the skin lesions in pityriasis versicolor?
Lipid degradation by the fungus produces acid, which damages melanocytes, leading to pigmentation changes (inhibiting tyrosinase).
58
How is pityriasis versicolor treated?
Topical selenium sulfide (e.g., Selsun Blue).
Promotes the shedding of the stratum corneum where the fungus resides.
Oral ketoconazole.
Terbinafine.
59
What are the three genera of dermatophytes responsible for tinea infections?
Trichophyton
Epidermophyton
Microsporum
60
Seborrheic dermatitis is caused by over secretion of the sebaceous glands due to a hypersensitivity reaction to _____________ .
Seborrheic dermatitis is caused by over secretion of the sebaceous glands due to a hypersensitivity reaction to Malassezia spp.
61
What can be used to determine the extent of the disease caused by Malassezia spp.?
Use of a Woods Lamp.
62
What are the common species categories of dermatophytes based on their habitat preference?
Anthropophilic (human-loving)
Zoophilic (animal-loving)
Geophilic (soil-loving)
63
Tinea capitis is and infection of the ... ?
Scalp
64
Tinea corporis is and infection of the ... ?
Body
65
Tinea cruris is and infection of the ... ?
Groin (jock itch)
66
Tinea pedis is and infection of the ... ?
Feet (athlete’s foot)
67
Tinea unguium is and infection of the ... ?
Nails (onychomycosis)
68
What are the diagnostic tools for dermatophyte infections?
Usually clinically diagnosed
Recommended for support of diagnosis:
KOH prep to visualize hyphae.
Wood’s lamp for fluorescenceof Microsporum, Trichophyton, or Epidermophyton.
69
What are the common risk factors for tinea corporis (ringworm)?
Skin-to-skin contact
Contact with infected animals
Humid environments
70
What is the appearance of tinea infections on the skin?
Red, scaly, and annular (ring-like) plaques with central clearing and pruritus.
71
how is tinea corporis (ringworm) treated?
Topical azoles
oral terbinafine
72
What are common clinical features of tinea capitis?
Scaly patches with alopecia (hair loss).
Often fluoresces under Wood’s lamp in cases caused by Microsporum.
Black dots with hair shaft.
73
How does tinea capitis spread?
Combs, pillows, hats.
Prevent by not sharing these items with others.
74
What are the treatments for tinea capitis infections?
oral terbinafine or griseofulvin.
75
What is onychomycosis, and how is it treated?
A fungal infection of the nails causing thickened, discolored nails.
Subungual debris can lead to the separation of nail plate from bed.
Treated with oral terbinafine, griseofulvin, or azoles.
76
What are the risk factors for tinea unguium (onychomycosis)?
Nail trauma
Prolonged exposure to moisture (e.g., wet environments)
Diabetes or peripheral vascular disease
Poor nail hygiene
77
What are the risk factors for tinea pedis (athlete’s foot)?
Wearing tight, non-breathable shoes
Walking barefoot in communal showers or locker rooms
Excessive sweating
78
What are the subtypes of tinea pedis (athlete’s foot)?
Interdigital
Moccasin
Vesiculobullous
All can cause redness and scaling between toes and on the foot.
79
How is tinea pedis (athlete’s foot) treated?
topical azoles or oral terbinafine.
80
What are the risk factors for tinea cruris (jock itch)?
Obesity
Wearing tight or wet clothing
Excessive sweating, especially in hot climates
Shared gym equipment
81
How is tinea cruris treated?
topical azoles or oral terbinafine.
82
Which dermatophyte infection commonly affects wrestlers?
Tinea corporis (ringworm).
83
What are the risk factors for tinea capitis (scalp infection)?
Sharing combs or hats
Contact with infected individuals or animals
Poor scalp hygiene
84
Are dermatophytes part of the normal skin flora?
No
85
What microorganism is most commonly involved in the pathogenesis of tinea capitis?
Trichophyton tonsurans
86
Which subtype of tinea pedis (athlete’s foot) is most common?
Interdigital
87
What type of fungus is Candida albicans?
Candida albicans is a catalase-positive, urease-positive, dimorphic fungus that exhibits pseudohyphae and budding yeast.
88
How is Candida albicans tested in a laboratory?
Candida albicans can produce germ tubes when incubated in serum at 37°C.
89
What populations are particularly vulnerable to Candida infections?
- Neutropenic individuals
- Diabetics
- People with HIV/AIDS
- Intravenous drug users
- Central indwelling catheter or recent surgery
90
What specific infections are commonly seen with Candida infections in the population with AIDS/HIV?
Patients with AIDS or HIV are at high risk for mucosal (eg, oropharyngeal, vulvovaginal), esophageal, and cutaneous Candida infections. Cutaneous Candida typically manifests as intertrigo, an erythematous, pruritic, weeping patch of skin; umbilicated lesions would be atypical (more indicative of cryptococcosis). Invasive and disseminated Candida infections primarily occur in patients who are being treated with chemotherapy or have hematologic malignancy or stem cell/solid organ transplantation. Patients with advanced HIV are at high risk for mucocutaneous Candida infections (eg, thrush, vulvovaginitis), invasive infections are extremely uncommon unless there is a portal of entry (eg, indwelling central catheter) or other major risk factor for invasion (eg, chemotherapy, hematologic malignancy, gastrointestinal surgery). In addition, Candida skin lesions do not typically cause umbilication or central necrosis.
91
What are the common clinical manifestations of Candida infections?
Oral candidiasis (thrush)
Candidal esophagitis (AIDS-defining illness, often with CD4 <200)
Candidal vulvovaginitis
Diaper rash
Candidal endocarditis
92
What condition is associated with candidal esophagitis?
Candidal esophagitis is an AIDS-defining illness, often observed when CD4 counts drop below 200.
93
Which populations are at risk for candidal endocarditis?
Intravenous drug users are at higher risk for candidal endocarditis, which can affect the heart valves.
Candida endocarditis predominantly affects the tricuspid valve in IV drug users and individuals with prosthetic heart valves and indwelling catheters.
94
What condition is associated with obese patients or those with diabetes and candidal infection?
Candidal intertrigo
Burning red plaques in the skin folds with surrounding satellite macules.
Affects the gluteal creases, inframammary folds, inguinal creases, and abdominal pannus.
Diagnosed clinically but supported with KOH prep or fungal culture
Treated with topical azoles or nystatin.
95
What makes Candida albicans dimorphic?
Candida albicans is a dimorphic fungus, but differs from other dimorphic fungi in that it exists in its yeast-form at 23-25 °C and a multicellular hyphal form at 37°C.
96
Vulvovaginal candidiasis often presents with
Burning, irritation, pruritus and a thick white vaginal discharge.
Usually odorless.
97
what is the underlying cause of Vulvovaginal candidiasis?
Overgrowth of normal vaginal flora.
Other species possible like glabrata.
98
what increases the risk of Vulvovaginal candidiasis?
Diabetes, antibiotics, IUDs, hormonal pills, or immunosuppression.
99
In vulvovaginal candidiasis, the vaginal pH typically remains within the normal range of
3.8 - 4.5
100
What is the treatment for Vulvovaginal candidiasis?
Topical azoles (clotrimazole, miconazole), or nystatin
then
PO Fluconazole
Amphotericin B can be used in cases of severe or fluconazole-resistant
Candida infections
101
Vulvovaginal candidiasis caused by glabrata is treated with ... ?
intravaginal boric acid.
102
What is characteristic of oral thrush?
Candida albicans causes oral thrush, which is characterized by white, scrapable lesions in the mouth; oral thrush is frequently seen in individuals using inhaled steroids and in immunocompromised patients
103
What is used for disseminated candidiasis?
Echinocandins, such as caspofungin and micafungin, are options for treating severe or refractory cases of candidiasis, including esophageal and systemic infections.
104
What evaluation is needed for patients who have disseminated candidemia?
Ophthalmoscopy is required in those with disseminated candidemia.
105
A 10-year-old boy is brought to the clinic by his parents due to a long history of recurrent oral thrush, nail infections, and persistent skin rashes. On examination, there are white plaques on the tongue and buccal mucosa that scrape off easily, erythematous skin lesions, and thickened, discolored fingernails. Laboratory workup reveals normal neutrophil count, normal immunoglobulin levels, but low T-cell-mediated responses on in vitro stimulation tests. Genetic testing confirms a mutation in the autoimmune regulator (AIRE) gene.
Which of the following is the most likely underlying mechanism of this patient’s condition?
A. Impaired B-cell development
B. Neutrophil dysfunction
C. Defective T-cell immunity
D. Complement deficiency
E. Increased pro-inflammatory cytokine production
C. Defective T-cell immunity
Explanation:
The patient presents with chronic mucocutaneous candidiasis (CMC), characterized by recurrent Candida infections involving the skin, nails, and mucosal surfaces. CMC is most commonly associated with T-cell dysfunction, specifically an impaired Th17 response, which is crucial for defense against fungal infections.
The mutation in the AIRE gene points to an association with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome, a rare autosomal recessive condition that includes endocrine abnormalities and chronic Candida infections. In this case, defective T-cell-mediated immunity allows Candida overgrowth despite normal neutrophil and antibody responses. The other associated issues may be type 1 diabetes or thyroiditis.
106
A 45-year-old male with a history of acute myeloid leukemia undergoing chemotherapy presents with fever, pleuritic chest pain, and hemoptysis. His absolute neutrophil count is 100/μL. Chest CT reveals a nodular infiltrate with surrounding ground-glass opacity (halo sign).
What is the most likely diagnosis, and what is the first-line antifungal treatment?
A. Candidiasis; Amphotericin B
B. Mucormycosis; Posaconazole
C. Invasive Aspergillosis; Voriconazole
D. Cryptococcosis; Fluconazole
E. Histoplasmosis; Itraconazole
C. Invasive Aspergillosis; Voriconazole
Explanation: Immunocompromised state and imaging findings are classic for invasive aspergillosis. Voriconazole is the treatment of choice for this condition.
107
What are the characteristics of Aspergillus spp.?
Catalase-positive fungi. Catalase allows them to neutralize reactive oxygen species, enhancing survival.
Aspergillus spp. is considered to be opportunistic.
Aspergillus spp. exhibit characteristic septate hyphae with acute branching angles, often around 45 degrees.
108
How is Aspergillus transmitted?
Aspergillus spores are inhaled, often from fruiting bodies in decaying organic matter.
109
Which Aspergillus species produces aflatoxins, and what condition does it cause?
Aspergillus flavus produces aflatoxins, which are linked to hepatocellular carcinoma.
110
What is ABPA, and who is at risk?
Allergic Bronchopulmonary Aspergillosis (ABPA)
Hypersensitivity reaction to Aspergillus spp., is characterized by migratory pulmonary infiltrates, fever, wheezing, and elevated serum IgE levels, and it most commonly affects individuals with cystic fibrosis or asthma.
111
Bronchiectasis is associated with ________, which is a hypersensitivity reaction to Aspergillus
Allergic bronchopulmonary aspergillosis (ABPA)
Note: Bronchiectasis is the permanent dilation of airways.
112
Key Features of Allergic Bronchopulmonary Aspergillosis (ABPA) include ...
Fever
Migratory pulmonary infiltrates
Recurring episodes or exacerbations
Wheezing
Elevated IgE
Coughing up brown mucous plugs
113
Lung cavities secondary to Aspergillus from conditions like tuberculosis, leading to symptoms such as cough and hemoptysis is likely a(n) .... ?
Aspergilloma (Fungus Ball)
114
Where do aspergillomas typically form?
In pre-existing lung cavities caused by conditions like TB, sarcoidosis, or emphysema.
115
Symptoms of aspergillomas include ... ?
Cough
Hemoptysis
Visible as gravity-dependent mass on imaging (shifting with positional changes).
116
In the context of Aspergillus, what does a previous TB infection predispose a patient to and how does this present?
History of lung disease or TB infection (cavitation) can lead to Chronic pulmonary aspergillosis which presents as an illness with a subacute onset. Symptoms include weight loss, productive cough, hemoptysis, dyspnea, fever and night sweats.
117
Management of Allergic Bronchopulmonary Aspergillosis (ABPA) includes ...
Serological testing of Aspergillus IgE or skin testing
Acute flares treated with corticosteroids to reduce inflammation and voriconazole or itraconazole to decrease fungal load.
118
Aspergillus accounts for ____ % of fungal infective endocarditis
30
119
What is the management of Chronic pulmonary aspergillosis?
- Imaging of the upper lobes for a possible fungus ball
- Serology for IgG
- Treatment is with **Systemic Steroids** during the acute phase of infection and the appropriate antifungal therapy is with either **itraconazole** or **voriconazole** as these medications have been shown to reduce the Aspergillus load and, therefore, the antigenic stimulus for ABPA. In addition, antifungal therapy has been demonstrated to decrease glucocorticoid requirements. Surgical resection is the last resort.
120
Who is at risk for invasive aspergillosis, and what are the clinical features?
- Seen in immunocompromised patients (e.g., neutropenia, organ transplant).
- This organism can lead to pulmonary, reticuloendothelial, and cutaneous manifestations, the skin lesions tend to be papular or pustular without umbilication.
121
Symptoms of invasive aspergillosis include .. ?
Fever
Chest pain
Hemoptysis
Dissemination to CNS, kidneys, sinuses, and heart.
122
What are the hallmark radiological features of invasive aspergillosis?
Nodular infiltrates with halo sign (ground-glass opacity)
Air crescent sign in later stages.
Gravity-dependent lesion that moves with changes in position.
123
How is Invasive Aspergillus infection diagnosed?
- Sputum stain or culture
- Biomarkers (beta-D-glucan or galactomannan)
- Tissue biopsy if uncertain
- CT scan of the sinuses can sometimes be helpful in the diagnosis of invasive aspergillosis, which can occasionally cause disseminated infection in patients with advanced HIV.
124
How is Invasive Aspergillus infection treated?
- Voriconazole (with caspofungin if severe)
- Amphotericin B is used for severe or refractory infections.
125
What is Cryptococcus neoformans?
An opportunistic fungus that is urease-positive and heavily encapsulated.
126
What is the role of the polysaccharide capsule in Cryptococcus neoformans?
It inhibits phagocytosis and is a diagnostic feature of the fungus.
127
What environmental exposure is commonly associated with Cryptococcus neoformans?
Pigeon droppings.
128
Which population is most at risk for Cryptococcus neoformans infections?
Immunocompromised individuals, particularly those with HIV/AIDS.
129
What are common pulmonary symptoms of Cryptococcus infections?
- Cough, chest pain, or asymptomatic presentation.
- Those with an intact immune system tend to form granulomas and not show signs of infection.
- Commonly causes pneumonia in the HIV patient population when the CD4 count is less than 100
130
What clinical manifestation is most commonly associated with Disseminated Cryptococcus?
- Pneumonia, therefore, pulmonary infiltrates, dyspnea, and hypoxia may also occur. The respiratory tract is usually the portal of entry. Pulmonary infection is typically marked by rapidly progressive dyspnea, fever, hypoxia, and nodular pulmonary infiltrates with or without hilar/mediastinal lymphadenopathy.
- Meningoencephalitis, characterized by nonspecific symptoms that include fever, N/V, headache, neck stiffness, and sensitivity to light. Meningoencephalitis is the most common presentation of disseminated cryptococcus, yet, a small number of individuals develop disseminated disease without overt CNS manifestations.
- Skin lesions, where a classic hallmark of hematologic dissemination is the presence of skin papules with central umbilication that resemble molluscum contagiosum. Lesions may develop a central area of hemorrhage or necrosis, which is an important diagnostic clue. The head and neck are preferentially affected, but papules may appear on the torso, back, or extremities.
- Disseminated Cryptococcus can also affect the reticuloendothelial system, leading to hepatosplenomegaly and/or lymphadenopathy, the peritoneum, and the adrenal glands.
131
Why must all patients with signs of Disseminated Cryptococcus have a spinal tap, regardless of evidence of CSF infection?
Because the CNS is the most common site of dissemination (and because CNS infection requires more aggressive antimicrobial treatment), all patients with immunocompromised who have pulmonary or disseminated cryptococcal infection require lumbar puncture to evaluate for meningoencephalitis even in the absence of neurologic manifestations.
132
What staining technique is used to visualize Cryptococcus neoformans?
- The diagnosis is established when the yeast is identified on sputum culture and is supported by the presence of positive serum cryptococcal antigen.
- India ink stain, revealing encapsulated cells with clear halos against a dark background.
- This is largely replaced by the latex agglutination test or ELISA with CSF
133
What is the latex agglutination test used for in Cryptococcus infections?
Detecting the polysaccharide capsule antigen in serum and CSF.
134
What imaging finding is associated with Cryptococcal meningitis?
"Soap bubble" lesions in the brain's gray matter on MRI.
135
What is the initial treatment for Cryptococcal meningitis?
- A combination of amphotericin B and flucytosine for 2 weeks.
- Followed by maintenance therapy with fluconazole for 1 year.
- Patients with AIDS who develop cryptococcal meningitis may have increased intracranial pressure. Manifestations include headache, vomiting, visual changes, papilledema, and cranial nerve palsies. Patients may require repeated lumbar punctures to reduce the elevated pressure.
136
What is used to diagnose pneumonia secondary to Cryptococcus?
Bronchoalveolar lavage samples can be prepared with mucicarmine (red) or methenamine (silver) stain for diagnosis of pulmonary cryptococcosis.
137
Opportunistic fungi causing mucormycosis
Mucor and Rhizopus spp. are opportunistic fungi that primarily affect immunocompromised individuals (steroid users), including those with leukemia, neutropenia, and diabetes.
138
Primary risk factor for mucormycosis
Diabetic ketoacidosis (DKA) is strongly associated with mucormycosis due to elevated glucose and ketone levels that create an ideal environment for fungal growth.
139
Primary mode of entry for Mucor and Rhizopus spp.
Entry typically occurs via spore inhalation, with the fungi colonizing blood vessel walls.
140
Histologic appearance of Mucor and Rhizopus
Non-septate hyphae with wide-angle (90°) branching, often seen in tissue samples.
141
Common sites of mucormycosis invasion
The fungi can invade the cribriform plate to access the brain, leading to rhinocerebral mucormycosis and tissue necrosis.
142
Clinical hallmark of rhinocerebral mucormycosis
Black eschar visible in the nasal cavity or on the palate/turbinates, indicative of necrosis.
143
Imaging finding in rhinocerebral mucormycosis
Tissue necrosis and invasion of adjacent structures, often seen in advanced cases. Proliferation within blood vessel walls leads to thrombosis, ischemia, and tissue necrosis.
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How is mucormycosis diagnosed?
tissue biopsy
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Common environmental source of Rhizopus species
Rhizopus spp. are commonly known as bread molds and are found in decaying organic material.
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Primary treatment for mucormycosis
Combination of amphotericin B (antifungal therapy) and surgical debridement to remove necrotic tissues.
