Systemic mycoses

Question 1

General features

Answer 1

• Cause infection in immunocompetent and compromised hosts
• Endemic pathogens
• Dimorphic fungi: are molds at RT and budding yeast at body temp
• Acquired by inhalation

Question 2

Coccidiodomycosis 1

Answer 2

• Found in dust/soil, confined to southwest US, northern mexico, central/south america
• Spherical cells in tissue (dark halo with light center), mold hyphae in culture (segments of hyphae have distinct dark segments and light areas btwn them)
• The spherules will often have endospores inside
• Clinical: most ASx, may have self limited pneumonia (non productive cough, anorexia, typical Sx)
• Possible to get immune complex formation (san joaquin valley fever): rash, erythema nodosum, erythema multiform, arthritis

Question 3

Coccidiodomycosis 2

Answer 3

• Disseminates in 1% of pts to: skin (abscesses), bone/joints, meninges
• Risk factors for dissemination: extremes of age, male, filipino/african american, high serum titer, pregnancy, immunosuppression
• Buzz word locations: Tuscon (!) and bakersfield
• Dx: complement fixation test, culture, pathology (do not do skin test)
• TB and Cocci have same presentation so always have them both on a DDx
• Rx: fluconazole

Question 4

Histoplasmosis 1

Answer 4

• Found in moist surface soil w/ droppings from birds/bats
• Highly associated w/ mississippi and ohio river valleys (midwest)
• White fluffy mold when cultured (looks like Cocci hyphae), reproduces by arthroconidia (little spiky balls)
• Survives in macrophages, disseminates within them and causes granulomas
• Can be seen w/in the macs as dark “bubbles”: dark circles w/ light halo around them
• On their own look a lot like Cocci: dark circles w/ light centers
• ASx for most pts, primary acute histoplasmosis includes fever, non productive cough, arthralgia, myalgia, headache
• May leave residual calcified lesions but usually pts recover spontaneously

Question 5

Histoplasmosis 2

Answer 5

• On CXR can see many small scattered opacities
• Inflammatory sequelae: arthritis, pericarditis
• Disseminated histo: fever, weight loss, fatigue, oropharyngeal ulcers, hepatosplenomegaly, skin and BM involvement
• Progressive pulmonary histo: lung destruction, cavities, fibrosis
• Can lead to mediastinal fibrosis
• Dx via culture, pathology, serology (blood and urine) and Rx w/ itraconazole

Question 6

Blastomyces dermatitidis

Answer 6

• Distribution: ohio and mississippi, around great lakes (similar to histo but extends further north)
• No capsule but thick wall, round, broad-based budding yeast
• Acute blastomycosis (resolves spontaneously): fever, arthralgias, myalgias, headache, productive cough, pleuritic chest pain, erythema nodosa
• Chronic blastomycosis: chronic pulmonary and cutaneous blasto
• Dx via culture, path, and urinary Ag
• Rx w/ amphotericin B

Question 7

Aspergillus infection

Answer 7

• Not a systemic mycosis, but can infect immunocompromised individuals
• Never grows from blood cultures, grows in tissues as septated hyphae of 45 degrees
• Can see conidia bodies
• If they colonize a preexisting lung cavity can lead to aspergilloma
• In pts w/ allergic rhinitis or asthma can lead to hypersensitivity reactions
• In immunocompromised hosts can be acute (severe) or chronic (mild)
• Risk factors: immunocompromise, hematologic malignancy, pulmonary disease, environmental conditions (construction)

Question 8

Clinical syndromes of aspergillus

Answer 8

• ABPA: allergic bronchopulmonary aspergillosis (asthma, central bronchiectasis, elevated IgE/eosinophilia)
• Important to Dx ABPA from other aspergillus syndromes, since Rx of ABPA is CCS but Rx of the other syndromes ir antifungals
• Fungus ball: requires preexisting lung cavity, Rx is surgical resection (can affect immunocompetent individuals)
• Invasive pulmonary disease: seen in pts w/ immunosuppression
• Sx: fever, dry cough, dyspnea, pulm infiltrates, “halo sign” on CXR, air-crescent sign on CXR
• Invasive disseminated disease: brain, bone, skin