Pulmonary Fungal Infections: Systemic Mycoses

Question 1

Coccidiodes:

Answer 1

1. thermally dimorphic (mold/spherule)
2. endemic to US southwest
3. mold (mycelia) grows in wet weather, but infectious arthrospores (hyphae) released in dry weather with wind or excavation
4. spores inhaled and can change form (aside: spherules and endospores inside are NOT infectious)
5. 60% of cases are mild: asymptomatic or flulike clearance by innate (low dose) or containment by CMI with granuloma and giant cell formation with lymphocytes and histiocytes (if moderate dose); moderate cases: valley fever/desert rheumatism with pulmonary issues (mild pneumonia) and EN (means risk of DISSEMINATION is low and you have red tender nodules on exterior surfaces like lower legs); severe with major pneumonia or dissemination (either bare or in macrophages; hematogenous spread)
6. Risk factors: age, race (black or Filipino), pregnancy, immunocompromised, occupational high exposure
7. Diagnose by exam, history (of travel to endemic area), PPD (maybe), biopsy for spherules!!, culture for dimorphism (see cottony white mold with hyphae with arthrospores that are INFECTIOUS), serology for dissemination (which can be meningitis, osteomyelitis, soft tissue abscesses)
8. Treat if predisposed to complications (oral azoles), meningitis (fluconazole), pregnant or disseminated (Amphotericin B); (persisting lung lesions or disseminated: Amphotericin B and long-term itraconazole)

Question 2

Histoplasma:

Answer 2

1. thermally dimorphic (mold/yeast)
2. endemic to Ohio, Missouri, and Mississippi river valleys
3. soil-based (bird dropping, bat guano; construction site), infectious microconidia can be kicked up by construction projects
4. causes pulmonary symptoms, previously-healthy can clear or contain in granulomas, and higher-dose infection produces TB mimic (cavitary lung lesions)
5. CMI-deficient host: disseminates in macrophages (yeast survive endocytosis and lysosomal fusion), and look for pancytopenia and ulcerations on tongue;
6. Diagnosis: history (birds, bats, endemic area, immunocompromised, occupation); biopsy for yeast in macrophages, cultures for dimorphism (25 will show tuberculate macroconidia, 37 for yeasts), ELISA for antigen; PPD NOT USEFUL; with spreading in lungs: cough, chest pain, hemoptysis, ARDS, cavitary lesions
7. Treat serious lung with itraconazole, meningitis with fluconazole, disseminated with Amphotericin B

Question 3

Blastomyces:

Answer 3

1. thermally dimorphic (mold/yeast)
2. endemic to Eastern US
3. Innate immunity clears most cases, destroys conidia easily (monocytes, macrophages, neutrophils), and yeasts are harder to kill (BAD1: immune-modulator)
4. granulomatous response contains most, immunosuppression predisposes to hematogenous spread
5. Mild: nonspecific flu-like illness; Moderate acute: pneumonia with purulent sputum; moderate chronic: mimics TB; severe acute: ARDS; may include EN or ulcerating skin lesions!!
6. Diagnose by sputum microscopy (KOH mount) for yeast, culture for hyphae with PEAR-SHAPED CONIDIA, biopsy for yeast with single broad-based buds, with supperating (NOT CASEATING) granulomas
7. treat with itraconazole, fluconazole if meningitis, Amphotericin B if severe!!!

B with b, c with c for diagnosis

Question 4

Paracoccidioides:

Answer 4

1. thermally dimorphic (mold/multibud yeast)
2. endemic to rural Latin America
3. Severe in children/immunocompromised; moderate in adults (usually men in agriculture or construction)
4. Adult form with LONG LATENCY, skin and mucous lesions (LAD, pulmonary symptoms, less severe); juvenile form more severe with LAD and HSM
5. Diagnose by pus or tissue KOH mount for multiple buds, cultures (takes 2-4 weeks)
6. Treat with itraconazole, Amphotericin B if severe, combine with healthier lifestyle (semi-opportunistic)