Medical Mycology (Habal) Flashcards
What fungus causes tinea corporis/cruris/pedis/capitis/unguium/manus? Clinical presentation: invasion of keratinized structures with possible secondary bacterial infections and mild inflammatory response in infected areas.
Dermatophytes
What fungus causes soft, pale nodules on hair in groin and axilla?
White Piedra - Tienea blanca, Trichosporon beigelii
What fungus causes and small, dark nodules on hair shaft)?
Black Piedra - Piedra hortae
What fungus causes Pityriasis versicolor - hypopigmented spots on chest, back, arms, shoulders, face, or neck? May also occur in lipid-dependent yeast in young adults with oily skin.
Malassezia furfur
What fungus causes Sporotrichoses (Rose Gardener’s Disease) - local pustules and ulcers with nodules at site of infection and along draining lymphatics? May also spread secondarily to articular surfaces, bone, and muscle.
Sporothrix schenckii
What may happen to the immunocompromised if they are infected by Sporothrix schenckii?
Fungus (Sporothrix schenckii) may become disseminated.
What fungus causes the “Summer Flu” of the Midwest?
Histoplasma capsulatum
What fungus may affect the spleen, liver, and bone marrow; is often asymptomatic, may resemble TB pneumonia as progressive lung disease, may cause ocular histoplasmosis, and disseminates in immunocompromised patients?
Histoplasma capsulatum
What fungus causes “Chicago Disease”; fever, night sweats & weight loss; pulmonary stage which may be followed by chronic granulomatous stage (lung & skin granuloma may ulcerate), and may affect the spine, pelvis, cranial bones, and ribs?
Blastomyces dermatitidis
What fungus causes “San Joaquin Valley Feve”; fever, productive cough, chest pain, extreme fatigue (usually self-limited), erythema multiforme & granulomas called Desert Bumps, is often associated with anorexia, and has symptoms that appear 7-28 days after exposure?
Coccidioides immitis
What fungus causes disease of the lungs and skin that rarely becomes systemic?
Paracoccidiodes brasiliensis
What fungus causes lung injury and meningioencephalitis (fever, loss of vision, stiff neck, mental status change, possibly hydrocephalus)?
Cryptococcus neoformans
What fungus causes infection ranging from mild (diaper rash) to fatal (systemic)? Name this infection.
Candida species - Candidiasis
What fungus causes vulvovaginitis, cutaneous candidiasis, oral thrush, esophageal candidiasis, and disseminated candidiasis?
Candida albicans
What is an AIDS-defining illness caused by a fungus? (Name the fungus as well.)
Esophageal candidiasis - Candida albicans
What fungus causes mycotoxicosis - ingestion of contaminated foods, possible precursor to liver cancer?
Aspergillus fumigatus
What fungus causes allergy/sequelae to presence of conidia or transient growth of organism in body orifices; colonization without extension in preformed cavities and debilitated tissues, and invasive, inflammatory granulomatous disease of lungs and other organs?
Aspergillus fumigatus
What fungus causes mold growth on organic material, such as bread?
Zygomycosis
What fungus causes large clots that lead to infarctions & pneumonia; has no boundaries, causes headache & orbital cellulites, leads to cerebral nerve palsy, hemorrhage, coma, and death if not treated?
Zygomycosis - Mucor or Rhizopus
What fungus causes bilateral infiltrate in lungs, fever, non-productive cough, breathing difficulty, respiratory failure, cyanosis, death by asphyxia, and rarely, extrapulmonary disease? 100% fatal if untreated.
Pneumocystis jiroveci
What is the most common fungal cause of pneumonia?
Pneumocystis jiroveci
What fungus can cause disease at sites distant to local infection and severe GE disease similar to cryptosporidiosis in AIDS?
Microsporidiosis
Which fungi cause superficial infections?
Piedras, Dermatophytes, Malassezia furfur
Which fungus causes subcutaneous infections?
Sporothrix schenckii
Which fungi cause systemic fungal infections?
Histoplasma capsulatum, Blastomyces dermatitidis, Coccidiodes immitis, Paracoccidiodes brasiliensis
Which fungi are opportunistic mycoses?
Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus, Mucor rhizopus, Pneumocystis jiroveci
What do fungi release and why?
Release enzymes to degrade the environment for nutritive purposes.
Fungi exist in what type of form? What does this mean?
They are thermally dimorphic - can exist in different forms, yeast or mold, depending on temperature.
What are the 4 components of fungal structure?
Polysaccharide capsule, cell wall, cell membrane, cytoplasm
What is the only encapsulated fungus we’re discussing?
Cryptococcus neoformans
Describe the cell membrane of fungi.
Similar to eukaryotic cell membrane - bilayered, made up of phospholipids and sterols, the latter of which is very important as some organisms need nutrients in order to synthesize them.
Describe yeast.
Unicellular, asexual budding reproduction, sexual reproduction, may contain capsule (identified via India ink), aerobic, grows at wide range of temperatures (optimum at room temp)
Describe mold.
Aerobic, filamentous, multicellular, spore/conidia reproduction, filaments known as hyphae (collection = mycelium, collection of these = mycelia, collection of these = mold
What is a defining characteristic of hyphae? What is the name for this, and is it characteristic of all mold?
Fenestrated septate - separations in hyphae that allow for transfers of material between compartments. Not all hyphae have these; they’re known as unseptate hyphae.
What is pseudohyphae?
Lack of cytoplasmic connections between cells - see constriction in middle.
Which fungus is pseudohyphae?
Candida
What is a germ tube?
Hyphae sticking out of a spore. This is a virulence factor that is very invasive when systemic.
What does fungal pathogenesis ultimately depend upon? What else?
Transmission is #1, but also depends on immune response.
How are most fungal infections transmitted?
Via the environment.
Which fungi are transmitted via human-human contact?
Dermatophytes
What are the 3 main ways to ID fungus in a lab?
Sabouraud’s agar, blood agar, microscopy
How many fungi appear as hyphae in the body?
2
In what form do most fungi present in the body?
yeast
Describe superficial mycoses.
Confined to stratum corneum or distal portions of hair, mostly cosmetic, generally have no cellular response from host, and essentially elicit no pathological changes.
What fungus invades keratinized structures and may cause secondary bacterial infections and mild inflammatory response in affected areas?
Dermatophytes
How do you diagnose dermatophytes?
Branched hyphae on KOH wet mount or culture using either myobiotic agar or Sabouraud’s dextrose agar
What are the 3 types of dermatophytes, and which one is associated with humans?
Anthrophilic - person-to-person or fomite transmission, geopilic, zoophilic
What genera make up dermatophytes?
Microsporum, Epidermophyton, Trichophyton
Lab results show branched hyphae resembling spaghetti & meatballs shape. Yeast is spherical on KOH mount. Which fungus is this.
Malassezia furfur
What is the name of the manifestion of infection caused by a group of fungi called black mold?
Mycetoma
How are subcutaneous fungi transmitted?
Cut/abrasion/etc. allows traumatically inoculated spores to enter body, where they can then go into the lymphatic system. Macrophages can’t do anything to them, so you get granulomas.
What fungus are you likely to see world-wide, but more often in tropical areas?
Sporothrix schenckii
Describe the morphology of Sporothrix schenckii.
Grows as mold (hyphae) in soil and switches to yeast in human host.
What is the transmission of Sporothrix schenckii?
Traumatic implantation
What is the most common form of candida?
Oral thrush
Why are fungal infections a concern for obese patients?
Many skin folds make attractive warm, moist, and humid regions for fungi.
Which fungus can be spread via person-to-person contact?
Candida albicans
How are all systemic mycoses transmitted?
Via inhalation - lungs are the first site of interaction between fungus and immune cells. Spores turn to yeast in lower lobes; macrophages phagocytose yeast.
Budding single-cell organisms are which fungi?
Systemic mycoses - Histoplasma capsulatum, Blastomyces dermatitidis, Coccidiomeds immitis, Paracoccidiodes brasiliensis
Where can you find Histoplasma capsulatum?
Ohio-Mississippi River Valley
Which fungus loves nitrogenous waste found in soil?
Histoplasma capsulatum
Which fungus is seen often in caves, can be caught from spelunking, and is found in bat, pigeon, and chicken droppings?
Histoplasma capsulatum
Using KOH and Parker Ink, you see single-cell yeast that buds with a narrow base. Definitive diagnosis shows the organism to be positive for H-antigen. What is this?
Histoplasma capsulatum
What medium do you use to diagnose Histoplasm capsulatum?
Sabouraud’s dextrose agar, supplemented with 5% sheep blood
Which fungus would you most likely be infected with if you were East of the Mississippi River Valley or in Central America?
Blastomyces dermatitidis
Which fungus is round with a refractive wall and a single broad-based bud? Definitive diagnosis shows the organism to be positive for Exo-A-antigen.
Blastomyces dermatitidis
What fungus loves organic debris, such as soil, rotten wood, and beaver dams?
Blastomyces dermatitidis
Which fungus would you most likely be infected with if you were in the SW US, specificially in the San Joaquin Valley or Arizona?
Cocciodiodes immitis
Which fungus produces spherules?
Coccidiodes immitis
What is a spherule?
Sac holding endospores that sporulate and give yeast after being inhaled into lungs.
Which is the most virulent systemic mycoses, Histoplasma, Blastomyces, or Coccidiodes? Why?
Coccidiodes - inhalation of spherules
What happens when you inhale Coccidiodes?
Inhale spherules that settle in the upper respiratory tract, and produce flu-like symptoms, followed by granulomas, which can become skin granulomas.
What fungus are you likely to encounter in rural Latin America?
Paracoccidiodes brasiliensis
You encounter a single-cell yeast that exhibits multiple buds when budding - looks like a wheel with spokes on it. Which fungus is this?
Paracoccidiodes brasiliensis
Which fungus loves to grow on bird droppings and is associated with opportunistic infection?
Cryptococcus neoformans
Which fungus presents as a yeast only; does not have a relevant mold phase?
Cryptococcus neoformans
How is Cryptococcus neoformans transmitted?
Through inhalation
Which fungus is the only yeast to “phenol oxidase,” neutralizing the epinephrine oxidase system out of CNS?
Cryptococcus neoformans
Which fungus can be found as a budding yeast with an antiphagocytic polysaccharide capsule?
Cryptococcus neoformans
Diagnosis is a positive CSF culture of a urease positive organism that can be seen using bird seed agar and India ink. What is it?
Cryptococcus neoformans
What ubiquitous fungi is found throughout the world as normal body flora?
Candida species
In what forms can the Candida species appear?
Yeast, psuedohyphae, true hyphae
What kind of environment do Candida species require?
Slightly alkaline - pH of 7.4
Where does Candida albicans present on the body?
Skin and mucous membranes
What is a potential, threatening consequence of Candida albicans entering the body?
Endocarditis
How do antibiotics affect fungi of normal body flora?
They change the pH - fungi will grow at an alkaline pH. This happens when lactobacilis is present.
Axillae, groin, submammary folds, intergluteal fold, and interdigital spaces are common locations for what fungal infection?
Intertriginous candidiasis
These fungal infections are often associated with use of broad spectrum antibiotics in women, pregnancy, low vaginal pH, diabetes, and poor hygiene. What are they?
Vulvovaginal candidiasis and balantitis
Cloudy vision and lesions within the eye can be caused by what fungal infection that can be spread in the blood stream via indwelling catheters, IV drug abuse, and ocular trauma/surgery?
Ocular candidiasis
Which fungus is infectious at low doses?
Aspergillus fumigatus
Which fungus appears as a flowering sporangium with finger-like projections and V-shaped branching septate hyphae?
Aspergillus fumigatus
Which fungus does not exist as yeast and thus does not exhibit thermal dimorphism?
Aspergillus fumigatus
Which fungus will find an area/cavity to grow in lungs, where it will form a hyphae fungus ball?
Aspergillus fumigatus
Some organisms will secrete some type of ercotoxin that has symptoms of convulsions and gangrene, which are associated with certain foods. What organism does this?
Aspergillus fumigatus
What fungus does not exist as a yeast, but rather systematically as a non-spectate hyphae that branches at a right angle?
Zygomycosis (Mucormycosis)
What fungus is associated with the immunocompromised and elderly?
Zygomycosis (Mucormycosis)
Which fungus will you see in patients with uncontrolled diabetes who are nearing stages of acidosis?
Zygomycosis (Mucormycosis)
Which fungus will begin growing in nasal sinuses, causing headaches?
Zygomycosis (Mucormycosis)
Which fungus is associated with a high fatality rate for the immunocompromised and elderly?
Mucor/Rhiospus
What is the new name for Pneumocystis carinii?
Pneumocystis jiroveci
What is the cause of fungal pneumonia that is also an AIDS-defining illness?
Pneumocystis jiroveci
Risk factors for infection of this fungus include: CD4 count<200 cells/micro-L, prior PCP infection, oral thrush, recurrent bacterial pneumonia, and HIV. What fungus is this?
Pneumocystis jiroveci
The following are clinical signs and presentations of what disease: bilateral infiltrate in lungs (alveoli fill with foamy exudate containing organism), fever, non-productive cough, breathing difficulty on exertion/respiratory failure;cyanosis, death by asphyxia?
Pneumocystis jiroveci
