Mycology Flashcards
What are the general properties of fungi?
Haploid eukaryotes
Thick cell wall composed of chitin,glucan
Cytoplasmic membrane with ergosterol
2 basic morphologies: yeast and molds
What are the characteristics of yeasts?
Unicellular
Reproduce by budding or fission
Form pseudohyphae and germ tubes(candida albicans)
What are the characteristics of molds?
Multicellular Form mycelium and hyphae Can be asexual or sexual Can be septate with or without clamp connections Coenocytic hyphae
What are the characteristics of mold structure?
Form conidia (spores) which help fungi spread
What are the different mold structure?
Blastoconidia- buds
Sporangiospores in a sporangium- spores in a membrane
Conidiophores-free spores can be blow away by wind
Macroconidia
Microconidia
Chlyamydospore
What is the metabolism of fungi?
All fungi are free living and are pathogens
Live on preformed live/dead organic carbon
Can cause hypersensitivity (Chitin)
Ergosterol is the target for anti fungal
80S ribosomes are resistant to prokaryotic antibiotics
What are the major classes of fungal toxins?
Aflatoxins (carcinogens) Citrinin (nephrotoxin) Ergot alkaloids (convulsive and gangrenous) Fumonsins (carcinogens) Ochratoxin (nephrotoxin) Trichothecenes (bone marrow toxicity) Stachybotryotoxins (neurotoxin)
What is an example of alfatoxins and disease?
Aspergillus
Acute liver and hepatocellular carcinoma
What is an example of citrinin and disease?
Penicillium and Aspergillus
Nephrotoxin such as yellow rice disease in Japan
What is an example of ergot alkaloids and disease?
Claviceps
Convulsive and gangrenous forms of disease
What is an example of fumonsins and disease?
Fusarium
Transient abdominal pain and diarrhea, esophageal cancer
What is an example of ochratoxin and disease?
Aspergillus and Penicilium
Balkan endemic nephropathy , renal tumors
What is an example of trichothecenes and diseases?
Fusarium, Myrothecium, Stachybotrys, Trichoderma, Cephalosporium
Gastointestinal hemorrhage and vomiting, direct contact causes dermatitis, moldy grain intoxication, red mold disease, alimentary toxic aleukia (ATA)
What is an example of stachybotryotoxins and diseases?
Stachybotrys
Contact dermatitis
Sick building syndrome
What is the characteristics of type 3 hypersensitivity?
Due to inhalation of allergen Causes pulmonary diseases such as: bronchial asthma Farmers lung Byssinosis-cotton fungus Pigeon fancier’s disease (feces)
what is the purpose of treatment with 10% potassium hydroxide?
When collecting a sample through scraping of the epidermis, there are a lot of human cells mixed with the fungi
Treatment allows destruction of the human cells to isolate fungi cells.
What are the positive staining to visualize fungi?
Lactophenol cotton blue Periodic acid Schiff Mucicarmine Grocott-Gomori methenamine silver Less effective are H&E and gram stain
What is the negative staining?
India ink is used
Especially for Cryptococcus neoformans
What are the fluorescent techniques?
Fluorescent staining of chitin with Calcophor
Fluorescence under UV light (Wood’s lamp)
How to culture fungi in lab?
Sabouraud’s agar (low pH, high glucose) inhibits bacteria
Mycological agar (mycosel)-good for isolation of dermatophytes
Chloramphenicol inhibits bacteria
Cyclohexamide inhibits rapidly growing mold contaminants
What are the ways the body fight off fungal diseases?
Body temperature of 37C Transferrin for own iron sequestration Alkaline pH of skin Skin fatty acid Fungal disease occurred when innate resistance is compromised and are self limiting
what are the classifications of fungal infections?
Superficial mycoses-outermost layer Cutaneous mycoses-into epidermis Subcutaneous mycoses Systemic mycoses-usually start from lung Opportunistic- involve IC patients
What are the characteristics of superficial mycoses?
Disease: pityriasis versicolor
Agent: Malassezia furfur
Symptoms: hypo or hyper pigmented macules
ID: hyphae and yeast like elements. «Spaghetti and meatballs»
What are the agents of the cutaneous mycoses?
Microsporum Trichophyton Epidermophyton Penetrate the keratinized skin, hair, nails Disease: Tinea Symptoms: Ringworm lesion
What are the sources of the cutaneous mycoses?
Anthropophilic- person to person, mild and chronic
Zoophilic-animal to person, inflammatory and acute
Geophilic- soil loving to person, severe
What are the characteristics of trichophyton?
Have numerous microconidia and rare macroconidia
What are the characteristics of microsporum?
Have numerous macroconidia and rare microconidia
What are the characteristics of epidermophyton?
Have only macroconidia and no microconidia
What are the diseases of the subcutaneous mycoses?
Sporotrichosis or Rose-grower’s disease
Mycotic keratitis
Initiated via skin or eye trauma
What are the characteristics of sporotrichosis or Rose- growers disease?
Agent:Sporothrix schenckii
Symptoms: nodules and ulcers along lymphatics or fixed site of inoculation
ID: budding, cigar shaped yeast @ 37C
Rosette pattern @ 25 C
What are the agents of mycotic keratitis?
Fusarium Solani- Crescent shaped macroconidia Candida albicans (pseudohyphae) Alternaria species (unusual macroconidia)
What are the symptom of mycotic keratitis?
Raised corneal ulcers with occasional satellite lesions, plaques and hypopyon (pus in the anterior chamber)
What are the agents of systemic mycoses?
Histoplasma capsulatum causes histoplasmosis
Blastomyces dermatidis causes North American blastomycosis
Paracoccidiodes brasiliensis causes South American blastomycosis
Coccidioides immitis causes Coccidioidomycosis
What are the characteristics of histoplasmosis?
Found along major midwest river valleys (Ohio, Mississippi)
5% affected with cough, chest pain, hoarseness resulting in acute or chronic progressive lung disease
95% contaminated calcification with no symptoms
Rarely a primary skin disease, usually a secondary lesion in the skin
How to ID histoplasmosis?
@ 25C mold with tuberculate macroconidia
@ 37C in vivo small yeast parasitic in a macrophage
@ 37C in vitro yeast form in chains
Buckshot appearance
What are the characteristics of North American blastomycosis?
Symptoms: Granulomatous and suppurative lesions of the lung with eventual skin lesions, resembles tuberculosis
ID: Thick walled yeast with a broad base @ 37C
Broad base budding yeast
What are the characteristics South American Blastomycosis?
Initial lung disease with metastasis to skin and many organs
Long latency with positive skin test, restricted to central and South America
ID: @ 25C septate hypha
@ 37C yeast with multiple buds
«Captain ship wheel»
What are the characteristics of coccidioidomycosis?
Flu like to disseminated due to delayed hypersensitivity
Mostly in SW USA and Mexico
ID: @ 37C spherule filled with endospores
@ 25C septate hyphae with arthrospores
Erythema nodosum (red bumps) common
What are some opportunistic infections?
Candidiasis caused by C. Albicans, C. Glabrata Cryptococcosis by C. Neoformans Pneumocystis pneumonia by P.jiroveci Aspergilosis by A. Fumigatus Mucomycosis by Rhizopus, absidia, Mucor Microspora by Enterocytozoon bienusi
What are the symptoms of candidiasis?
Itchy white patches of creamy or cheesy growth in the mouth, vagina, esophagus, urethritis (burning while urinating)
Occurred worldwide and associated with AIDS, diabetes, IC host
How to ID candidiasis?
C. Albicans produced germ tubes in serum
All other candida produced pseudohyphae and chlamydospores when grown on corn meal agar
What are the characteristics of the crytococcosis?
Mild lung infection followed by skin lesion and meningitis
ID: yeast with a large capsule (C. Neoformans only yeast producing capsule)
India ink stain
What are the characteristics of Pneumocystis pneumonia?
Common childhood infection reactivated in AIDS patients
ID: Characteristics cysts with cup forms and dot like cyst wall thickenings in lung with methenamine silver stain
What are the characteristics of Aspergillosis?
Disease in IC patients, fungus ball in the paranasal sinus, lung or brain
ID: hyphae with acute angles
Mold with septate, multinucleate mycelium with a coenocytic, rough conidiophore
What are the characteristics of mucormycosis,zygomycosis?
Diabetes associated
Fungus ball in eyes, sinus, lung leading to necrosis
ID: hyphal forms
What are the characteristics of microspora , microsporidia?
Slim disease
AIDS associated chronic diarrhea
Spores seen by gram staining urine, CSF
