Deep Mycoses

Fungi Causing Systemic Mycoses = majority causes inapparent infection = causative organism are dimorphic fungi 1. Blastomyces dermatitides Characteristics: = dimorphic can exist as: mold in soil, yeast in tissue Yeast form is round-shaped with a thick refractile wall and single broadbased bud = natural habitat Is soil rich in organic material

Disease: Blastomycosis (Gilchrist’s Dse, North American) Blastomycosis = a chronic infection characterized by formation of suppurative and granulomatous lesion found mainly in the lungs and disseminate throughout the body MOT = inhalation of airborne spore (conidia) Pathogenesis: = infection occurs mainly in the respiratory tract = inhaled conidia differentiate into yeast cell which initially cause abscesses

Laboratory Diagnosis: 1. Direct microscopic examination of sputum or skin scrapping (KOH mount)/Tissue biopsy: = demonstrate charac. thick walled “yeast cell with single broad-based bud” 2. Culture - SDA = grows as fluffy, brownish to white fungus which produces pyriform spores 3. Hypersensitivity test – Blastomycin test = Serological test not useful Treatment: Itraconazole (drug of choice) Amphotericin B - used to treat severe cases

2. Coccidiodes immitis Characteristics: = dimorphic fungus that exist as: spherules in tissues containing endospores mold at 250C in soil which forms hyphae with alternating arthrospores = natural habitat is soil Disease: Coccidiodomycosis (San Joaquin Valley Fever,) Dessert Fever = disease simulate pneumonia wherein large part of the lung becomes consolidated MOT: inhalation of airborne arthrospores Pathogenesis: Arthrospores inhaled →to the lungs

Septate hyphae

Septate hyphae

Arthroconidia

Laboratory Diagnosis: A) Microscopic examination of tissue scrapping or sputum (KOH mount) = demonstrate the characteristic spherules containing endospores B) Culture Sabouraud medium – presence of hyphae containing arthrospores. C) Serological test Precipitin test– demonstrate a rising titer of IgM Ab (indicates recent infection) CF test - a rising titer IgG antibody indicates dissemination of infection D) Skin test – Coccidioidin test – using mycelial extract or spherulin (an extract from spherules) as

Treatment: Ketoconazole (for primary infection) Amphotericin B/Itraconazole (for disseminated infection) Fluconazole - drug of choice in cases of meningitis Prevention: No vaccine and Prophylactic drug available

3. Paracoccidiodes braziliensis Characteristics: = dimorphic fungus exist as: mold in soil yeast in tissue (yeast form is thick walled with multiple buds) resembling a ship steeringwheel = habitat - soil Disease: Paracoccidioidomycosis (South American Blastomycosis) = chronic granulomatous disease of the skin,mucous membrane, lymph node and internal organs. MOT : inhalation of airborne conidia Pathogenesis: = spores are inhaled an early

Laboratory Diagnosis: A) Direct microscopic examination from pus or tissues (KOH mount) = presence of large yeast cell w/multiple buds B) Culture Sabourauds agar – presence of septate hyphae with microconidia C) Skin test not useful D) Serological: CF/Immunodiffusion test - rise in AB titer significant Treatment: Itraconazole

4) Histoplasma capsulatum = dimorphic fungus that exist as: yeast cell in tissue w/c forms 2types of asexual spore a) Tuberculate macroconidia (thick-walled finger like projection) b) Microconidia- thin, small, smoothwalled mold in soil enriched with bird droppings

Disease: Histoplasmosis (Darling’s Disease) = acute, benign pulmonary disease acquired by inhalation of airborne spores (microconidia) which are present from dropping of birds = inhaled spore are engulfed by macrophages which

Laboratory Diagnosis: A. Microscopic examination of sputum, tissue biopsy, bone marrow aspirate = oval yeast cell within macrophages B. Culture Sabourauds agar = presence of septate hyphae with tuberculate chlamydospore in culture at 250C is diagnostic BHIA – presence of fusiform blastospores with large vacuole giving a characteristic cresent-shaped appearance C. Skin test – Histoplasmin test -using mycelial extract as antigen -useful for epidemiologic determination of incidence of infection -not use to diagnose actual disease

Budding yeast cell inside macrophages

Fungi Causing Opportunistic Mycoses = produce disease in those individual with impaired host defenses 1. Candida albicans Characteristics: = is an oval yeast cell with a single bud = part of the normal flora of the mucous membrane of the upper respiratory tract, gastrointestinal and female genital tract = in tissues can appear as yeast cell or as psuedohyphae (which are elongated yeast that

MOT: - part of the normal of the skin, mucous membrane and gastrointestinal tract of human = no person to person transmission Pathogenesis: Opportunistic pathogen = disease may results when host defenses are impaired Diseases: 1. Thrush (Moniliasis) 2. Vulvovaginitis 3. Infection of the Nail (Paronychia) 4. Skin lesion occurs frequently in moisturedamage skin

Laboratory Diagnosis: A. Direct microscopic examination (KOH mount) = presence of budding yeast cell w/pseudohyphae B. Culture SDA – presence of yeast cell, pseudohyphae and large chlamydospore Germ tube form in serum at 370C differentiate albicans from other species C. Skin test with candida antigen = (+) among immunocompetent adult and

Treatment: Nystatin / Miconazole oral/topical for skin and mucous membrane disease Amphotericin B - disseminated infection Ketoconazole – for chronic mucocutaneous candidiasis Prevention: No vaccine available = predisposing factors should be reduced or eliminated = Clotrimazole trochis / Nystatin–used for prevention of oral thrush

2. Aspergillus fumigatus/Aspergillus flavus/Aspergillus niger

Characteristics: = exist only as mold with septate hyphae that branch at a V-shaped angle = monomorphic = organism is normally found in soil Diseases: 1. Aspergillosis (major disease) = a granulomatous necrotizing disease of the

lung

which often disseminates hematogenously

to

organ

various organs of the body = involving the skin, eyes, ear, and other vital

Pathogenesis: = opportunistic pathogen = produce invasive disease among munocompromised individual = organism can invade bloodvessels causing ombosis and infarction = patient with lung cavity (tuberculosis) may velop fungal ball (Aspergilloma) = allergic patient with bronchial asthma can velop allergic bronhopulmonary aspergillosis Laboratory Diagnosis: A. Microscopic examination (KOH mount) = presence of hyaline septate hyphae, dichotomously

Treatment: Amphotericin B – for invasive aspergillosis Surgical removal – for aspergilloma (fungus ball) Steroid – recommended for allergic bronchopulmonary aspergillosis Prevention: No vaccine / Prophylactic drug available

3. Rhizopus/Mucor Characteristic: = mold with non-septate hyphae w/ sporangiospore that typically branch at 90O angle = monomorphic = habitat in soil MOT: inhalation of airborne spores Disease: Mucormycoses (Zygomycoses; Phycomycoses) = is a systemic disease cause by saprophytic mold (Mucor, Rhizopus and Absidia) found widely

Laboratory Diagnosis: 1. Microscopic examination of tissue (KOH mount) = presence of non-septate hyphae that branch at wide right angle 2. Culture – SDA - large hyaline coenocytic hyphae with spores found inside sporangium 3. Serologic test – not available Treatment: Amphotericin B Prevention: No vaccine / Prophylaxis drug available

4. Cryptococcus neoformans = is an oval yeast-like budding cell surrounded by a wide polysaccharide capsule = not dimorphic = habitat soil enriched with pigeon droppings Disease: Cryptococcosis(Torulosis, European Blastomycosis) = most common life-threatening fungal disease in AIDS patient MOT: inhalation of airborne yeast cell = no human to human transmission Pathogenesis: = lung infection as a result of inhalation is often asymptomatic or may produce

Laboratory Diagnosis: = Direct visualization of the encapsulated yeast-like budding cell from spinal fluid by India Ink staining (yeast cell surrounded by a wide unstained capsule) = Culture (spinal fluid/sputum) SDA – presence of encapsulated yeast cell. = Serological – Latex particle agglutination test - detects polysaccharide capsular antigen in spinal fluid Treatment: Amphotericin B plus Flucytosine for meningitis Prevention: No vaccine

Capsule

Budding yeast