XII - Mycology Flashcards
Fungi are ___karyotic
eukaryotic
Fungi have complex carbohydrate walls composed of
chitin, glucan, mannan
Major membrane sterol in fungi
ergosterol
Antifungals: Inhibit ergosterol synthesis
Imidazole
Antifungals: Bind more tightly to ergosterol than cholesterol
Polyene
Fungi require _____ (heterotrophic nutrition).
organic carbon
Living in dead organic matter
saphrophytic or saprobic
Living on another living organism
parasitic
Basic Forms of Fungi: Single cells, budding
yeast
Basic Forms of Fungi: Hyphae, mycella (bouquet of hyphae), mitosis
molds
Fungi exhibit thermal _____.
thermal dimorphism
Hyphae: Septate
transverse walls
Hyphae: Non-septate
multinucleated
Basic Forms of Fungi: Room Temp.
mold
Basic Forms of Fungi: Body Temp.
yeast
Host response to fungal infection
granulomatous, pyogenic
Fungi: Liver necrosis due to amantin and phylloidin
Amanita mushrooms
Fungi: Ingestion of contaminated peanuts and grains causes liver cancer due to aflatoxin
Aspergillus flavus
Fungi: Inhalation of the spores cause allergic bronchopulmonary aspergillosis (ABPA, IgE-mediated)
Aspergillus fumigatus
Fungi Diagnosis: Dissolves human cells allowing visualization
KOH microscopy
Fungi Diagnosis: Low pH inhibits the growth of bacteria
Sabouraud agar
Fungi Diagnosis: Used for early infection
DNA probes
Fungi: Infect only superficial keratinized structures
Dermatophytoses
3 Important Dermatophytes
Microsporum canis, Trichophyton tonsurans, Epidermophyton floccosum
Dermatophytoses: Transmission
direct contact, dogs, cats
Chronic infections in warm, humid areas of the body, inflamed circular border containing papules and vesicles surrounding a clear area of normal skin
Dermatophytoses
Fungi hypersensitivity causes
dermatophytid reactions (different site from contact)
Dermatophytoses: Athlete’s Foot
Tinea pedis
Dermatophytoses: Nails
Tinea ungium
Dermatophytoses: Ringworm
Tinea corporis
Dermatophytoses: Jock Itch
Tinea cruris
Dermatophytoses: Hands
Tinea manuum
Dermatophytoses: Scalp
Tinea capitis
Dermatophytoses: Facial Hair
Tinea barbae
Dermatophytoses: Diagnosis
10% KOH - septate hyphae, Sabouraud agar - hyphae and conidia, green fluorescence on Wood’s lamp
Dermatophytoses: Treatment
local antifungal creams, keep skin dry
Tinea versicolor (an-an), superficial skin infection of cosmetic importance, hypopigmented patches, spaghetti and meatballs (hyphae & yeast) appearance on 10% KOH
Malassezia furfur
Malassezia furfur: Treatment
Miconazole
Dimorphic fungus that lives on vegetation, gardeners who prune roses
Sporothrix schenckii
Sporothrix schenckii: Transmission
thorn prick
Sporothrix schenckii: Treatment
Itraconazole, Potassium Iodide
Dimorphic fungus that exists as a mold in soil and as a spherule (yeast) in tissue, endemic in arid regions of the southwestern US and Latin America
Coccidioides immitis
Coccidioides immitis: Transmission
inhalation of arthrospores
Arthrospores form spherules filled with endospores, granulomata in bones and CNS, dissemination in those who have defective cell-mediated immunity
Coccidioides immitis
Influenza-like illness, lung infiltrates, adenopathy, effusions, erythema nodosum (desert bumps), arthralgias, meningitis
Valley Fever (Coccidioides immitis)
Coccidioides immitis: Treatment
Amphotericin B, Itraconazole, Fluconazole - meningitis
Dimorphic fungus, forms 2 types of asexual spores
Histoplasma capsulatum
H. capsulatum Asexual Spores: Typical thick walls and finger-like projections, important in laboratory identification
tuberculate macroconidia
H. capsulatum Asexual Spores: Smaller, thin, smooth-walled spores, transmits infection if inhaled
microconidia
Endemic in Ohio and Mississippi River valleys, grows in soil contaminated with bird droppings (starlings) or bat guano
Histoplasma capsulatum
Histoplasma capsulatum: Transmission
airborne microconidia
Closely mimics TB, chronic pneumonia, erythema nodosum, tongue ulcerations in AIDS patients
Histoplasma capsulatum
TB Mimickers
Paragonimus, Histoplasma
Histoplasma capsulatum: Treatment
Amphotericin B, Itraconazole, Fluconazole - meningitis
Dimorphic fungus, round yeast with broad-based bud, endemic in Northeastern America (Ohio, Mississippi)
Blastomyces dermatitidis
Blastomyces dermatitidis: Transmission
inhalation of conidia
Most common cause of fungal pneumonia
Blastomyces dermatitidis
Chronic pneumonia, ulcerated granulomas, lytic bone lesions, prostatitis
Blastomyces dermatitidis
Blastomyces dermatitidis: Treatment
Itraconazole, Amphotericin B - severe infections, Fluconazole - meningitis
Dimorphic fungus, thick yeast with multiple buds (mariner’s wheel), restricted to Central and South America
Paracoccidioides brasiliensis
Paracoccidioides brasiliensis: Transmission
inhalation of conidia
Paracoccidioides brasiliensis: Diseases
chronic pneumonia, painful ulcers on mouth and nose
Paracoccidioides brasiliensis: Females are protected because of
estrogen
Paracoccidioides brasiliensis: Treatment
Itraconazole
Predisposing Factors for Opportunistic Mycosis
broad-spectrum antibiotics, steroids, hematologic malignancies, transplant recipients, systemic chemotherapy, AIDS
Normal flora of upper respiratory tract, GI, female GUT, may appear as oval yeast with a single bud or as pseudohyphae, form germ tubes in serum and chlamydo-spores in culture
Candida albicans
Candidiasis: Oral thrush, vulvovaginitis → curd-like discharge, intertrigo, skin infections → satellite lesions, onychomycosis
immunocompetent
Candidiasis: Pseudomembranous esophagitis, subcutaneous nodules, right-sided endocarditis
immunocompromised
Candidiasis Treatment: Oropharyngeal and Esophageal
Nystatin - swish and swallow
Candidiasis Treatment: Skin
Clotrimazole
Candidiasis Treatment: Disseminated
Amphotericin B
Candidiasis Treatment: Chemoprophylaxis
Fluconazole
Oval yeast with narrow-based bud surrounded by a wide polysaccharide capsule seen in India ink, positive latex agglutination test (CALAS), grows in soil containing bird droppings (pigeon)
Cryptococcus neoformans
Cryptococcus neoformans: Transmission
inhalation of airborne yeast cells
Cryptococcus neoformans: Diseases
asymptomatic lung infection, meningitis, encephalitis
Cryptococcus neoformans: Treatment
Amphotericin B, Flucytosine, Fluconazole - chemoprophylaxis
Exists only as molds, septate hyphae that form V-shaped (dichotomous) branches, acute angles
Aspergillus fumigatus
Aspergillus fumigatus: Location
widely distributed in nature
Aspergillus fumigatus: Transmission
inhalation of conidia
Infects wounds, burns, cornea, external ear, sinuses, aspergilloma (fungus ball) in lung cavities, allergic bronchopulmonary aspergillosis (ABPA) - asthmatic symptoms with expectoration of brownish bronchial plugs
Aspergillus fumigatus
Aspergillus fumigatus: Treatment
Amphotericin B
Saprophytic molds with non-septate hyphae with walls and branches at right angles, rhino-orbital-cerebral infection with eschar formation, patients with DKA, burns leukemia
Rhizopus oryzae and Mucor
Indeterminate organism, major surface glycoprotein undergoes programmed rearrangements, diagnosis by bronchoalveolar lavage (BAL) washings, toluidine blue, methenamine silver stain
Pneumocystis jiroveci
Pneumocystis jiroveci: Transmission
inhalation of cysts
Cysts in alveoli induce an inflammatory response consisting of plasma cells, frothy exudate blocks oxygen exchange
Pneumocystis jiroveci
Occurs when CD4 < 200, diffuse interstitial pneumonia with bilateral ground glass infiltrates, 100% mortality rate if untreated
Pneumocystis jiroveci
Most common AIDS-defining illness
Pneumocystis jiroveci
Pneumocystis jiroveci: Treatment
Trimethoprim-Sulfamethoxazole