04b: Fungi Flashcards
List the three major mechanisms by which fungi can cause disease in people:
- Toxin
- Allergy (rhinitis/asthma)
- Direct infection
T/F: Like plants, fungi have chlorophyll.
False
Fungi that derive nourishment from dead/composing organic material have (X) existence.
X = saprophytic
Fungi that use material from living organism in mutually beneficial way have (X) existence.
X = symbiotic
Fungi that use material from living organism for its benefit (but is neither beneficial nor harmful for host) have (X) existence.
X = commensal
Fungi that use material from living organism in manner that harms host have (X) existence.
X = parasitic
Fungi are (prok/euk). They (have/lack) nucleus/nuclear membrane and organelles, have (X) ribosome, and (have/lack) cell wall.
Eukaryotic;
Have (golgi)
X = 80S
Have rigid cell wall
T/F: Fungal cell wall structure similar to bacterial cell wall.
False - contains chitin, mannan, and beta-glucan
Medically important fungi can be either moist, waxy colonies called (X) or branching tubular filaments called (Y)
X = yeast Y = hyphae (mass = "mold")
(Yeast/hyphae) cells are round/oval and typically reproduce by which mechanism(s)?
Yeast;
Budding (small outgrowth) or fission (splitting into equally-sized daughter cells)
(X) are elongated (yeasts/hyphae) with constrictions between cells. Looks like chain of sausages.
X = pseudohyphae
Yeasts
T/F: Hyphae can be either septate or aseptate.
True
How to molds reproduce?
Hyphae produce spores (conidia)
Thermally dimorphic fungi appear as (X) in environment and as (Y) in mammals. What stimulates this phase-transition?
X = mold Y = yeast
In-vivo conditions (esp 37oC)
T/F: Gram stain is useless for all fungi.
False - all except Candida (gram-pos)
Due to their (X), fungi are resistant to degradation by hot alkali. Thus, (Y) prep can be used to visualize fungi in lab.
X = cell wall Y = KOH
(X) stain is good for visualizing fungi, which stain black.
X = Silver
(X) stain is good for visualizing fungi, which stain red.
X = PAS
When fungal infection is suspected, specimens should be plated on special medium, (X) agar.
X = Sabouraud;
(X) are (superficial/subcutaneous/systemic) mycoses (mold) that can invade keratinized tissues by virtue of their ability to metabolize (Y).
X = dermatophytosis
Superficial;
Y = keratin
Most common sites of dermatophytosis.
Scalp, beard, feet, groin, nails
“Tinea pedis” aka “athlete’s foot” is (superficial/subcutaneous/deep) mycosis caused by (X) molds.
Superficial;
X = dermatophytosis
T/F: Dermatophytosis can be treated topically.
True
(X) is a common, superficial fungal infection that produces (hypo/hyper)-pigmented lesions, generally on trunk/proximal limbs.
X = tinea versicolor
Either hyper or hypo-pigmented lesions
Dandruff is (X) of the scalp. This is primarily an inflammatory reaction to (Y) species. It presents with which symptoms?
X = seborrheic dermatitis Y = Malassezia (fungal)
Erythema, scaling, itching
“Madura foot” aka (X), is (superficial/subcutaneous/systemic) mycosis. It’s a(n) (acute/chronic) infection that presents with which symptoms?
X = Mycetoma
Subcutaneous;
Chronic
Swelling, nodules, sinus tracts
How can dermatophytes be spread to humans?
- Other humans
- Soil
- Animals
Onychomycosis is what kind of (bacterial/fungal) infection? It’s more commonly found in which population?
Fungal; superficial mycosis (dermatophytosis) of (toe) nails
More common in elderly population
Which dermatophytosis (superficial mycosis) is more commonly found in pediatric population?
Tinea capitus (of scalp)
Which fungal species responsible for Tinea versicolor?
Malassezia species
(X) is the most common species of Candidiasis. The agents form (yeast/hyphae) in tissue.
X = Candida albicans
Yeasts, hyphae, and pseudohyphae
Unlike most systemic mycoses, which are acquired via (X), (Y) infections are generally acquired via (Z).
X = inhalation of airborne spores Y = Candida Z = endogenous infection
Mucocutaneous candidiasis is seen in patients with (X).
X = defects in T cell-mediated immunity, diabetes, on broad spectrum antibiotics
Disseminated candidiasis is seen in patients with (X).
X = neutropenia, IV cath, surgery
“Thursh” aka (X) is often the first clinical manifestation of (Y).
X = oral (mucocutaneous) candidiasis Y = HIV
Which two agents are responsible for Cryptococcosis?
- Cryptococcus neoformans
2. Cryptococcus gattii
(X) is the only medically important fungus with a capsule, which circulates in (Y) body compartments and is useful for diagnosis.
X = Cryptococcus;
Y = blood and CSF
Which fungal agent is found worldwide, with high concentrations in soil, bird droppings, and rotting wood?
Cryptococcus
Cryptococcus has strong association with (X) disorders.
X = T-cell immunity (esp. AIDS)
Also transplants
(X) is the most common clinical presentation of C. neoformans.
X = meningitis
Patient with meningitis. You suspect Cryptococcus (X) infection. What could you measure to verify this?
X = neoformans
CSF would have high protein, low glucose (maybe), and be positive for Cryptococcal Ag
Which drug would you use for extensive mucocutaneous candidiasis?
Fluconazole
And, if possible, eliminate predisposing condition (ex: discontinue broad spectrum antibiotics)
(X) is the most common fungus in the environment. What is the spectrum of disease conditions/mechanisms it can cause?
X = aspergillosis
Allergic, Aspergilloma, Invasive
Patient has pre-existing pulmonary cavity. You suspect (X) species of (bacteria/fungus) is residing in that cavity. What are you afraid that agent will do?
X = aspergillosis
Fungus
Can either chill or invade vessels (hemorrhagic infarction)
Patient on chemo (weak immune system) is at risk for (X) invasive fungal infection. With very low (Y) WBCs, infection by this agent can have pt mortality over 50%!
X = aspergillosis Y = PMNs
Black, necrotic lesion is classic presentation of (X) fungal infection. Which patients have predisposition?
X = mucormycosis
Diabetic ketoacidosis, neutropenia
(X) is the most common life-threatening infection in AIDS patients in US. What’s the infectious agent responsible?
X = pneumocystis pneumonia
Pneumocystis jiroveci
Patient with pneumocystosis (PCP) will have which clinical presentation?
Pneumonia (fever, non-productive cough, SOB);
Chest X-ray will show diffuse interstitial infiltrates
T/F: Pneumocystis jiroveci cannot be cultured.
True
(X) fungal agent is endemic in Ohio and Mississippi River valleys, Caribbean, and Central America. Exposure to (Y) is risk factor. (Z) patients are particularly susceptible.
X = Histoplasma capsulatum Y = bird/bat droppings Z = AIDS
Histoplasmosis diagnosis in immunocompetent patients is via (X) test. And in AIDS patients is via (Y) test.
X = serology Y = urine antigen
(X), also known as “valley fever”, is endemic in San Joaquin valley, SW US, and parts of Latin America. Which fungal agents are responsible?
X = Coccidioides
- Coccidioides immitis
- Coccidioides posadasii
(X) fungal species forms mature spherule in lung, filled with (Y). If the spherule bursts, all the (Y) have which fate?
X = coccidioides Y = endospores
Spread and can develop into new spherules
T/F: Coccidioides infection doesn’t occur in immunocompetent patients.
False - but more common in those with impaired CMI (esp AIDS)
(X) fungal agent has multiple buds that look like “pilot wheel” or Mickey Mouse. Where is this infection endemic?
X = Paracoccidioides brasiliensis
South America (esp Brazil and Colombia)
(X) fungal agent is mold in (nature/tissue) and large, broad-based yeast buds in (nature/tissue). It’s endemic in SE and Central U.S. as well as the Great Lakes.
X = Blastomyces dermatitidis;
Nature; tissue
Being pricked by rose thorn puts you most at risk for which fungal infection?
Sporothrix schenckii
(X) fungal infection is endemic in areas of SE Asia and nearly all cases are seen in (Y) patients. Unlike most yeasts, reproduction of this agent is via (budding/fission).
X = Talaromyces (penicillium) marneffei Y = AIDS
Fission
Colonization of (X) species of fungus is common in humans.
X = candida
