E2- Fungal Infections Flashcards
What are the two types of cutaneous fungi?
Malassezia furfur
Hortaea weneckii
What do dermatophytes require for growth?
Keratin (hair, nails, skin; do not infect mucosal surfaces)
Which fungi genuses have sexual spores?
Microsporum
Trichophyton
What is the infective stage of fungal disease?
Arthroconidium
What can be used to visualize arthroconidium microscopically?
10% KOH wet mount
What is trichophytin
Galactomannan peptide
Crude antigen of dermatophytes
CHO component immediate response
Peptide component delayed response
What kind of medium allows for early detection of a dermatophyte infection?
Dermatophyte test medium
Selective and differential
What color will dermatophytes appear on DTM media?
Red color change Dermatophytes utilize nitrogenous compounds over carbohydrates Change pH (alkaline)
What class of dermatophytes have animal pathogens that can be transmitted to people?
Zoophilic
What class of dermatophytes spread through human transmission?
Antrophophilic
What class of dermatophytes are transmitted through soil to people and usually invade non-viable keratinized tissue?
Geophilic
What area of the body do dermatophytes usually inhabit?
Moist areas
What are some risk factors for dermatophyte infections?
Communal bathing facilities, immunocompromised status, Cushing’s syndrome, contact sports
Disseminated dermatophyte disease is possible in what type of patients?
HIV
What is an allergic dermal reaction to fungal antigens occurring in areas devoid of organisms?
Dermatophytid reaction
What is the most common Dermatophytid infection?
Tinea pedis
Are Dermatophytid spores generally susceptible or resistant to common disinfectants, chlorine, bleach, and detergents?
Susceptible
What 3 Trichophyton species are most common?
Trichophyton tonsurans
Trichophyton rubrum
Trichophyton mentagrophytes
Are Trichophyton species typically fluorescent or non fluorescent?
Non fluorescent
What Dermatophytid species all make pencil-shaped macroconidia with thin walls?
Trichophyton species
What do Trichophyton species produce?
Hyphae (Spindle-shaped)
Microconidia
Macroconidia
What are species are the most common cause of tinea capitis?
Microsporum species
Microsporum canis
Are Microsporum species typically fluorescent or non fluorescent?
Fluorescent
What do Microsporum species produce?
Hyphae
Microconidia
Macroconidia (large, spindle-shaped, multicellular, thick walled)
What is infected in tinea barbae?
Beard
What is infected in tinea manus?
Hand
What is infected in tinea ungium?
Nails (onychomycosis)
What is most common causative agent of tinea capitis?
Microsporum canis
What are the two varieties of tinea capitis?What species cause each?
Endothrix- Trichophyton
Ectothrix- Microsporum
How does black dot tinea capitis occur?
Occurs when infected hair breaks off leading to alopecia
Can tinea capitis be zoonotic?
Yes
What are the most common causative agents of tinea pedis?
Epidermophyton floccosum
Trichophyton mentagrophytes
Trichophyton rubrum
What are the most common causative agents of tinea corporis and tinea cruris?
Microsporum canis
Epidermophyton floccosum
Trichophyton mentgrophytes
Trichophyton rubrum
What are some predisposing factors for tinea corporis and tinea cruris?
Diebetes
Obesity
Excessive persiration
How is tinea corporis and tinea cruris transmitted?
Direct and indirect contact
towels, clothing, bed linens
What are the most common causative agents of tinea unguium?
Epidermophyton floccosum
Trichophyton mentagrophytes
Trichophyton rubrum
What is the most commonly encountered opprtunistic mycoses (fungal/yeast infection) worldwide?
Candidiases
Does Candida albicans have many virulence factors?
No
What form Candida albicans is more adhesive than the parental yeast cells?
Germ tube
How is Candida albicans dx?
Direct microscopic examination
Candida are polymorphic fungus that can grow as what?
Budding yeast
Pseudohyphae
Germ tube
True hyphae
What type of agar used to dx Candida infections?
Chromagar
What can be used to determine the species of a Candida infection?
Serology to detect presence/absence of germ tubes
What two Candida species have germ tubes?
Candida albicans
Candida dubliniensis
What is the causative agent of tinea verisolor?
Malassezia furfur
What does Malassezia furfur look like under microscopy?
Short unbranched hyphae and spherical cells
“Spaghetti and meatballs”
Which pathogen has a lipophilic growth factor? What does this mean?
Malassezia furfur
Requires fat to grow (commonly sebaceous glands)
How is tinea versicolor dx?
KOH prep and microscopy
What is the causative agent of Tinea nigra?
Hortaea weneckii
Is Tinea nigra caused by yeast or mold?
Dimorphic species that can grow as yeast and/or mold
What type of conditions can Hortaea weneckii grow in?
Saturated salt solutions
Extremely halotolerant
What is the clinical presentation of Tinea nigra?
Brownish lesions
Fungus produces melanin
How is Tinea nigra dx?
KOH prep and microscopy
What is a structure unique to dermatophytes?
Trichophytin