Exam 5 Mycology Flashcards
Fungi cell wall contains:
Chitin, mannoproteins, glucans
Fungi cell membrane contains ____
Ergosterol
Which 5 major classes of fungi cause human disease?
- Mucormycetes
- Basidiomycetes
- Pneumocystidiomycetes
- Saccharomycetes
- Euascomycetes
Fungi can have what kinds of morphology?
- Yeasts
- Hyphae
- Dimorphic
____ are unicellular and reproduce by budding
Yeasts
What is the structure of hyphae?
- Multicellular
- Septate or non-septate
____ are masses of hyphae (____)
Mycelia; molds
What does dimorphic mean?
Different forms at different temperatures (yeast at 37C, mycelia at 25C)
Most species of fungi form ____
Spores
Fungi can undergo asexual reproduction to form what kinds of asexual spores?
- Sporangiospores
- Conidia
Sporangiospores are formed within ____
Sporangia (sac)
Conidia are formed at ____ or by ____
Tips of hyphae; hyphal fragmentation
Arthrospores form via ____ and are a type of ____
Hyphal fragmentation; conidia
Sexual reproduction in fungi is by means of ____
Sexual spores (zygospores)
Zygospores are formed by:
Nuclear fusion of 2 haploid cells
Fungal nutrition: yeasts use ____ and molds use ____
Facultative anaerobes; mainly aerobes
Fungal colonies can be cultured on what mediums?
- Sabouraud agar
- Pagano-Levin agar
Sabouraud agar usually contains ____ and incubate aerobically in ____
Antibacterial agents; high humidity
What is Pagano-Levin agar used for?
To distinguish different Candida species
Microscopic examination of fungi can be done through what techniques?
- Potassium hydroxide (KOH)
- India Ink
- Gomori methamine silver (GMS) stain
- Immunofluorescence of chitin
____ preparation is cheap and fast, and can be used for oral, vaginal, skin scrapings or squamous epithelial cells scrapings
KOH preparation
True or false: antigen or antibody detection is another fungal identification method
True
What do polyenes do?
Anti-fungal therapy that binds to ergosterol and disrupts cell membrane
What do azoles inhibit?
Ergosterol synthesis
____ inhibit cell wall (glucan) synthesis
Echinocandins (Micafungin)
Naftifine inhibits:
Ergosterol synthesis
Griseofulvin inhibits:
Mitosis
Malassezia infects what layer?
- Superficial (epidermis)
- outermost layers of skin
Describe Malassezia classification
- Lipophilic
- Budding yeast-like cells
What disease does Malassezia cause?
Tinea versicolor
What are some very common diseases caused by Malassezia?
- Folliculitis
- Venous catheter infection
Malassezia Tinea versicolor lesions can appear ____ or ____
Hypo or hyperpigmented
Dermatophytes infect what part of the skin?
Dermis (cutaneous)
List the names of the 3 dermatophytes
- Trichophyton
- Microsporum
- Epidermophyton
____ cause Tinea
Dermatophytes
What is Tinea?
Ringworm-shaped mycoses
Tinea caused by dermatophytes are classified by what?
Structure affected
Trichophyton commonly affects what parts of the body?
Skin, hair, nails
Trichophyton rubrum is the most common cause of ____
Athlete’s foot
Trichophyton tonsurans is the most common cause of ____
Tinea capitis (scalp)
Microsporum affects what parts of the body?
Skin and hair
Epidermophyton affects what parts of the body?
Skin, nails
Another name for tinea pedis
Athlete’s foot
Tinea unguium (onychomycosis) is common in people with ____
Weakened immune system
Which fungi infect subcutaneous tissue (fat)?
- Pseudallescheria boydii
- Fonsecaea pedrosi
What does Pseudallescheria boydii cause?
- Mycetoma
- Disseminated disease in immunocompromised patients
____ causes chromoblastomycosis
Fonsecaea pedrosi
True or false: Candida albicans and Candida auris are multi-drug resistant and cause opportunistic infections
True
What is an important and most common predisposing factor for infection with opportunistic fungi?
Broad-spectrum antibiotics
Broad-spectrum antibiotics have a dose-dependent exposure, meaning that ____ people may become infected by ____
Healthy/immunocompetent; Large doses
True or false: Candida species are common flora of the oral cavity, skin, genital tract, and gut
True
Candida are ____ (shape)
Polymorphic (dimorphic)
____ form chlamydospores
Candida species
What are chlamydospores?
- Spores formed on pseudohyphae in starvation conditions
- Globular structures on hyphal tips (bulb like structures)
True or false: only some morphological forms of Candida spp. are important in virulence
False - all forms (polymorphic and dimorphic)
____ describes a transition between yeast cells, pseudohyphae, hyphae, and chlamydospores in Candida spp.
Polymorphic
____ describes a transition between yeast cells and filamentous mold forms in Candida spp.
Dimorphic
Oral candidiasis can take on many forms/severity, such as: (5)
- Pseudomembranous
- Erythematous
- Chronic hyperplastic
- Chronic atrophic
- Angular stomatitis
Pseudomembranous oral candidiasis causes:
“Thrush”, white lesions easily wiped off
Erythematous oral candidiasis is:
Painful, deep red, depapillated
Chronic hyperplastic oral candidiasis causes:
Confluent white plaques which cannot be removed
____ is seen in 60% of denture stomatitis and causes inflammation of the mouth and lips in elderly
Chronic atrophic
Angular stomatitis is also known as:
Cheilitis or perleche
____ causes redness after scraping off pseudomembrane
Erythematous candidiasis
What can cause denture stomatitis?
Dentures worn day and night and not cleaned or insufficient oral hygiene
____ causes inflammation, cracks, and red patches at the corners of the mouth
Angular stomatitis
Chronic mucocutaneous candidiasis causes:
Recurrent superficial Candida infections
On Sabouraud agar, Candida colonies appear:
Creamy
Some strains of ____ are resistant to all available antifungals
Candida auris
Candida auris has persistent transmissions in ____
Health care settings
____ causes high mortality
Candida auris
Name 5 opportunistic fungi pathogens
- Cryptococcus neoformans
- Aspergillus fumigatus, A. flavus
- Rhizopus sp, Mucor sp.
- Pneumocystis jirovecii
- Fusarium sp.
Cryptococcus neoformans has a _____ which makes it anti-phagocytic
Gelatinous alginate capsule
Where is Cryptococcus neoformans found as a spore?
Pigeon and chicken feces
What infections does Cryptococcus neoformans cause?
- Pulmonary
- Meningitis (especially in AIDS patients)
True or false: Cryptococcus neoformans infections in AIDS patients is moderately fatal
False - high fatality
What is the most common clinical manifestation of Cryptococcus neoformans?
Pulmonary
Where is Cryptococcus gattii endemic?
US Pacific NW
The DOC for Cryptococcus gattii is amphotericin B. Does it have a good or poor prognosis?
Poor prognosis
Aspergillus fumigatus/flavus has what type of hyphae?
Septate hyphae
Aspergillus fumigatus/flavus conidia (spores) can be inhaled into ____
Alveolar spaces
Aspergillus fumigatus/flavus antigens can cause ____
Hypersensitivity (induce respiratory disorders like allergies and asthma)
Aspergillus fumigatus/flavus infection in immunodeficient patients can cause ____
Pulmonary aspergillosis
What toxin does Aspergillus flavus produce?
Aflatoxin (mycotoxin)
What does aflatoxin cause?
- Acute hepatic necrosis
- Cirrhosis
- Hepatoma
Aflatoxin is usually found on ____
Peanuts
A multistate outbreak of fungal meningitis and other infections occurred in 2012. Which fungi were responsible?
- Aspergillus tubingensis
- Aspergillus fumigatus
Which fungi are the most common causes of mucormycosis?
- Rhizopus arrhizus
- Mucor indicus
____ are rapid growers (lid pushers)
- Rhizopus arrhizus
- Mucor indicus
Rhizopus arrhizus and Mucor indicus can reproduce via:
Sexual (zygospores) or asexual (sporangiospores)
____ is a risk factor for mucormycosis
Diabetic ketoacidosis
Why is diabetic ketoacidosis a risk factor for mucormycosis?
- Low insulin moves less glucose into cells
- Body burns fat for fuel and makes ketone byproducts
- Ketones make blood more acidic
- Acidosis reduces host defense and allows fungal growth
Where does mucormycosis cause disease?
- Rhinocerebral/rhinofacial
- lung
- skin
True or false: Mucormycosis is aggressive and mortality is up to 95%
True
Rhinocerebral/rhinofacial mucormycosis typically occurs in:
- Diabetics in ketoacidosis
- Patients on steroids or cytotoxic therapy
After eating contaminated food, Mucormysosis spores invade:
- Soft palate
- Sinuses
- Cribriform plate
- Brain and behind eyes
Pneumocystis jirovecii is an unusual fungus because:
It lacks ergosterol
____ has trophozoite and cyst forms
Pneumocystis jirovecii
Pneumocystis jirovecii is a major opportunistic pathogen in ____ and presents as ____
AIDS; pneumonia
DOC for Pneumocystis jirovecii
Trimethoprim-sulfamethoxazole
Fusarium sp. cause infections where?
Ocular (contact lenses)
Fusarium sp. infection can become ____ in immunocompromised patients
Systemic
Dimorphic fungi grow as ___ at 37 degrees C (body temp)
Parasitic yeast (tissue form)
Dimorphic fungi are ____ at 25 degrees C
Mold/hyphal/filamentous
Dimorphic fungi cause ____ involving any organ or skin and occur within ____ areas where >80% of population has immunity
Systemic mycoses; endemic areas
Histoplasma capsulatum causes ____ infection resembling TB
pulmonary
Histoplasma capsulatum is endemic where?
East/midwest
Blastomyces dermatitidis causes what disease?
Pulmonary, disseminates to skin and bone
Coccidioides immitis is endemic where?
Southwestern US
Coccidioides immitis parasitic form
Spherules (thick walled spheres containing endospores); NOT yeast form
Sporothrix schenkii causes spores on ____
Rose thorns (Gardeners, rose gardener’s disease)
After traumatic implantation, Sporothrix schenkii spreads where?
Up arm causing string of abscesses (regional lymphadenopathy, can disseminate)