Respiratory Fungi Flashcards
Rhizopus, Mucor/zugomycor, Absidia
Fungal opportunistic respiratory pathogen
- soil, air, water. black bread mold, rotting fruit.
- respiratory inhaled sporangiospores.
- monomorphic nonseptate irregular width hyphae with broad 90o branching angles with asexual spore (sporangium)
high Risk: immunocomppromised, ketoacidossis (diabetes), neutropenia, corticosteroid use. acute inflammation of soft tissue. fungal invasion of paranasal arteries, lungs, gut, oral mucosa
- Rhinocerebral infection Paranasal swelling, necrotic tissues, hemorrhagic exudates from nose and eyes, mental lethargy
- produce hydrolytic enzymes (saprophytes) causing tissue destruction. results in thrombosis, infarction, ischemic necrosis distal to blockage of arteries.
- rapid spread.
- mucorcycosis: pulmonary symptoms infarct f lung tissue, local hemmorrage (arterial blockage) , cavitation, fungus ball formation.
TX: surgical removal tissue, antifungal drugs (amphotericin B)
Use KOH, Sabouraud’s dextrose agar (SDA) cotton candy appearance (nasal discharge/sputume etc)
Aspergillus Fumigatus
Fungal opportunistic respiratory pathogen
- Ubiquitous saprophytes in soil and decaying vegtables composts.
- respiratory inhalation of spores
- monomorphic filamentous fungus. dichotomously branching at acute 45o angles.
- Allergic bronchopulmonary (high IgE) asthma, CF. growing in mucous plugs in lung but not penetrating tissue.
- Fungus ball: free in preformed lung cavities (surgical removal)
- Invasive: (severe neutropenic patient, burns, CF) invades tissue causing infarcts and hemorrhage. Nasal colonization (pneumonia / meningitis). Burned patient with disseminating cellulitis.
- mycotoxicosis: mold in grains and nuts produce aflatoxin carcinogenic.
Tx. amphotericin B, voriconazole. surgical removal if possible.
- use KOH to clear bacteria. Sabouraud dextrose agar with gentamicin or chlorampenicol (NOT cycloheximide which is used to supress fast growing normal fungi when trying to grow slow growers.)
- grow rapidly at room temp and form bloack, brown, or green colonies
- serology: IgE (RAST-radioallergosorbent test), galacto-mannan Ag in ELISA rapid test.
Pneumocystis Jiroveci (Carinii)
Fungal opportunistic respiratory pathogen. Carinii was considered a protozoa with trophozoites and cysts. Fungi lacking ergosterol based on nucleic acid and biochemical analysis (lacks ergosterol).
- worldwide animals and humans (nearly 100% seropositive),
- inhalation of spores/cysts.
- obligate extracellular parasite
High Risk: immunosuppressed AIDS patients (low CD4). steroid tx, organ tx, cancer patients.
-
pneumocystis pnumonia atypical interstitial pneumonia
- fever, cough, SOB, sputum nonproductive (except smokers)
- attaches and kills type I pneumocytes
- serum leaks to alveoli: foamy exudate with honeycomb. methenamine Silver stain reveals holes are the fugus.
- x-ray: patchy infiltrative (ground glass) lower lobe periphery
- extrapulmonary lesions occur in minority thru lymph nodes, spleen, liver, and bone marrow
Tx. trimethoprim-sulfamethoxazole (antibacterial, not antifungal)
- does not grow on fungal media (no culture media avail), not sensitive to anti-fungals
Blastomyces dermatitidis
Fungal regional respiratory pathogen. reportable disease!
- moist soil with decomposing organic debris/rotting wood endemic eastern USA and much of world.
- respiratory inhalation conidia (spores).
- env. mold hyphea with nondescript conidia
- tissue: broad based budding yeast and a double refractile cell wall, no capsule, extracellular (in sputum)
PATIENT: Acute and chronic pulmonary disease with disseminating infection (less likely to resolve than histoplasma or coccidiodes) incubation for weeks. pulmonary and extra pulmonary manifestations (mild flue like), severe resemble bacterial pneumonia: acute onset, fever, cough, lobular infiltrates (resp failure may occur). lesions may calcify. Chrnic pneumonia may ocur resembling tuberculosis or lung cancer. extrapulmonary hematogenous soread to skin and bone: chronic cutaneous lesions, painless nodules which may ulcerate (wart like on exposed skin)
Tx. amphotericin B, azoles. culture with KOH
Histoplasma capsulatum
Fungal regional respiratory pathogen
- “cave disease” respiratory inhalation of soil with bird/bat dropping. central US. eastern great lakes, ohio, mississippi, missouri rivers. Dimorphic:
- env. mold hyphae with microconidia and tuberculate macroconidia
- tissue: intracellular yeast narrow neck on bud, no capsule, in reticuloendothelial cells
PATIENT: asymptomatic. Fugus Flu. acute pulmonary self resolving pneumonia (patchy infiltrates, cavity lesion, Lesions calcify as the heal) with flu symptoms (mediastinal lymphadenopathy). hepatosplenomegaly.. T cell Immunocompromised have chronic relapse and disseminating mucocutaneous lesions (mouth ulcers).
- facultative intracellular. engulphed by macrophages develop to yeast divide by budding
- produce bicarbonate and ammonia (alkaline ph)
- carried to regional lymph nodes -liver/spleen
- bronchoalveolar lavage, tissue biopsy, bone marrow aspirate
- ELISA Ag urine/sera in disseminated disease
- Ab detect complement fixation or immunodiffusion assay
TX. Ketoconazole, amphotericin B
- sputum culture Sabouraud (blood agar with inhibitory mold)
- calcofluor white helpful
- peripheral blood cultures with mononuclear cells packed with yeast
Coccidioides immitis
Fungal regional respiratory pathogen
- soil in hot, semi arid areas. USA south-west coast (philipes and africa). respiratory inhalled spores.
- Env. mold hyphae breaking up to arthroconidia spores
- Tissue: spherules with endorspores. (in sputum)
PATIENT: Valley fever. assymptomatic to pneumonia flu like symptoms within 1-3 weeks (cough, malaise, chest pain). pulmonary lesions (calcify as they heal), Desert Bumps. tender erythema nodosum, desert rheumatism__: arthritis, arthralgias,, Disseminating in immunocompromise and pregnant women (CNA, bone, skin eruptions, soft tissue).
- Tcell response forms granuloma in some tissue (resembels old TB lesions - HSR IV)
Tx. Amphotericin B, azoles
- sputum/biopsy trest with KOH ,
- spherules do not grow in culture
- arthroconidia unsafe to culture
- serology IgM/G
