Mycology Flashcards
Saprophytes
Most fungi, feed on dead/decaying material
Parasites
Many fungi are parasites, feed on living organisms without killing them
Common characteristics of all fungi
Eukaryotes, can be multi- or uni-cellular, heterotrophic
Mycobacteria
GPB, acid-fast, aerobes, produce catalase, cause TB
Mycobacterium tuberculosis
No exotoxins or enzymes for infectiousness, complex waxes and cord factor that prevent destruction by lysosomes or macrophages
Primary TB
Infectious dose of 10 cells, at 3-4 weeks tubercles form, of tubercle breaks down, caseous lesions form
Secondary TB
Reactivation, tubercles expand and drain into bronchial tubes and upper respiratory tract, 60% mortality if untreated, more severe symptoms
Extrapulmonary TB
bacilli disseminate to regional lymph nodes, kidneys, long bones, genitals, brain and meninges, fatal
Mantoux test
Injection of purified protein derivative, look for red wheal to form within 48-72 hours, can diagnose TB
Mycobacterium leprae
causes leprosy, strict parasite, spread through direct inoculation
Tuberculoid leprosy
Superficial infection without skin disfigurement which damages nerves and causes loss of pain perception
Lepromatous leprosy
A deeply nodular infection that causes severe disfigurement of the face and extremities
M. avium
3rd most common cause of death in AIDS patients
M. kansaii
pulmonary infections in adult white males with emphysema or bronchitis
M. marinum
Water inhabitant, lesions develop after scraping on swimming pool concrete
M. scrofulaceum
Infects cervical lymph nodes
M. paratuberculosis
raw cow’s milk, recovered from 65% of individuals with Crohn’s disease
Actinomycetes
nonmotile filamentous bacteria related to mycobacteria, may cause chronic infection of skin and soft tissues
Actinomyces iseaeli
Responsible for diseases of the oral cavity, thoracic or intestines
Nocardia brasiliensis
causes pulmonary disease similar to TB
Teleomorph
The sexual stage of the fungus
Anamorph
the asexual stage of the fungus
Nocardiosis
subcutaneous infections, pulmonary infections, brain abscesses, N. asteroides and N. brasiliensis
LActophenol cotton blue
Quick evaluation of fungal structures, stains chitin in cell walls of fungi
PAS stain
Stains polysaccharide in cell wall of fungi, fungi stained pink-red with blue nuclei
Gomori methenamine silver stain
silver nitrate outlines fungi in black due to the silver precipitating on the fungi cell wall
Zygomycota
all fungi with nonseptate hyphae
Fungal yeasts
Candida spp. and cryptococcus neoformans
Dimorphic fungi
change from a multicellular hyphae form in the natural environment to a budding single-celled yeast form in tissue
Dimorphic fungal pathogens
Blasto, histo, paracoccidioides
Molds
filamentous fungi, coenocytic or have septa, have mycelium (tangled masses of hyphae)
Hyphae
increase surface area of fungi and facilitate absorption
Yeasts
Unicellular fungi, reproduce asexually (budding), grow on cornmeal agar
Candida
most common invasive fungal infection in immunocompromised patients, typically C. albicans, pseudohyphae (germ tube) or hyphae, rapid switching of expressed phenotype, form biofilm
Transplanted Kidney
makes someone super susceptible to disseminated candida infections
Diagnosing candida albicans
C. albicans is germ tube positive, other spp are negative
Candida infection
UTI, eye, liver and spleen, kidneys, skin, brain, lungs, bone
Cryptococcus
Encapsulated, inhalation of spores, yeast, asexual, opportunistic, seen in HIV/AIDS patients and in organ transplants
Crypto clinical manifestations
Lung (pneumonia), meningitis, disseminated in HIV, skin ulcers, genital, eyes
Immunodiffusion
For Histo (H + M band), Blasto, aspergillus and coccidioides
Identity
Bands connect, but do not intersect or cross
Non-identity
Bands cross in X shape
Partial identity
Bands for a Y shape
Aspergillus
airways/nasal exposure to airborne aspergillus, acute or chronic, characteristic conidiospore, conidia produced by phialides, characteristic for foot cell, typical mold seen on food
Fungal growth requirements
25-30 C for most fungi, dimorphic fungi grow best at 37 C
Aspergillosis fumigatus
Mycelium is septate, unbranched, rough or smooth conidiophores, foot cell, phialides are short flask shaped
Hulle cells
Seen in A. versicolor and A, nidulans, specialized multinucleate cells that originate from a nest-like aggregation of hyphae during sexual development and serve as nurse cells to developing cleistothecium (sexually reproductive part of A. nidulans)
Blastomyces dermatitidis
Hyphae with microconidia at room temp, pulmonary infection or chronic pulmonary disease, disseminated to skin and bones
Paracoccidioides brasiliensis
Hyphae at room temp, converts to yeast with multiple buds at 37 C, acquired by inhalation, acute, chronic or asymptomatic pulmonary infections
Mucormycosis
Fungal infection in immunocompromised or trauma patients, acute granulomatous and opportunistic infection, intrinsic ability to invade blood vessels, Rhinocerebralorbital mucormycosis is most common, seen in DKA
Rhinocerebral mucormycosis
Unilateral headache, facial pain, eye swelling, necrotic lesions on hard palate or nasal mucosa
Malassezia
Causes pityriasis versicolor, seborrheic dermatitis, dandruff and psoriasis, dimorphic fungus, normal skin flora, spaghetti and meatballs
Fusarium
Associated with mycetomas, keratitis and systemic infections, form septate hyphae and 2 forms of conidiation, corneal infections from contact lenses
Dermatophytes
Cause infections of the hair skin or nails, eat keratin in skin, most infections are in the feet or head/scalp, trichophyton, epidermophyton, and microsporum
Trichophyton
infects nails, hair and skin, T. verrucosum is negative in the hair perforation test, foot fungus common
Epidermophyton
Infects skin and nails, E. floccosum
Microsporum
infects hair and skin,
Tinea pedia
Athletes foot, caused by trichophyton and epidermophyton
Tinea corporis
Ringworm, caused by microsporum and trichophyton
Tinea unguium
Nail infection, caused by trichophyton and epidermophyton
Tinea capitis
Scalp infection, caused by trichophyton and microsporum
Tinea barbae
Infection of beard hair, caused by trichophyton and microsporum
Tinea cruris
Jock itch, caused by trichophyton and epidermophyton
Endothrix
Mold produces conidia inside hair shaft
Ectothrix
Conidia only on outside of hair shaft
Trichophyton mentagrophytes
Positive hair perforation test,
Microsporum canis
Positive hair perforation, most commonly seen dermatophyte
