Mycoses Of Veterinary Importance Flashcards
Thermally monomorphic mold is
Aspergillus
What do aspergillus colonies look like
- white at first
- then yellow, green, brown, or black
- velvety or cottony
Microscopic characteristics of aspergillus
- Septate hyphae and unbranched conidiophore that form a foot cell
- vesicles
What are often seen in culture preps of aspergillus
Chains of round conidia
Where does aspergillus affect K9s and horse?
- K9: nose
- horse: guttural pouch
Main type of aspergillus
A. fumigatus
Aspergillus infections
- by inhalation
- first airway infected (local inflamm. Resp)
- then potentially lethal invasive infection in immunocomp.
Yeast that is normal inhabitant of upper GIT and moist skin folds
Candida
Is candida local or systemic?
Both
A major nosocomial yeast is called
Candida
T or F: Candida can grow in the body as yeasts w/ pseudohyphae
True
Most common candida spp
C. albicans
Emerging spp of candida
C. auris
Candida auris
- drug resistant (multi)
- rapidly spreading, especially in healthcare facilities
- hard to ID
Pythium insidiosum causes what disease
Pythiosis
(Aka: swamp cancer, florida horse leeches, canckers, etc.)
2 forms of pythium insidiosum
- GIT
- Cutaneous
Areas where pythium insidiosum is common
Gulf coast & SE USA
Where do the spores of pythium insidiosum infect?
- lower extremities of exposed skin
- ingested w/ contaminated h2o
What is pythium insidiosum
Granulomatous ulcerative disease of skin and GIT
What zygomycetes cause zygomycosis
- mortierella
- absidia
Mucor
- rhizopus
T or F: Pythium insidiosum is motile
True
Characteristics of zygomycetes
- aseptate hyphae
- grow fast
What specific diseases can zycomycetes cause?
- gastritis in bovines
- mycotic abortion & placentitis in ruminants
- guttural pouch & cervico-uterine infections in horses
Why is the spread of zygomcyosis fatal
- angio-invasion
- thrombosis
Antifungal drugs
- polyene
- imidazole
- 5-fluorocytocine
- griseofulvin
- terbinafine
- caspofungin
Polyene drugs
- target ergosterol
- ex: aphotericin b & nystatin
Imidazole drugs
- ergesterol synthesis is target
- ex: “-azole” group; ketoconazole, fluconazole, etc)
5-fluorocytocine
DNA synthesis inhibitor
Griseofulvin
- binds tubulin
- interferes with/ fungal mitosis
- conc. In epith.
- teratogenic
Terbinafine
Ergosterol synth inhibitor
Caspofungin
Glucan synthase inhibitor
Yeast don’t have
Hyphae
Mold has
Spores
Characteristics of fungi
- eukaryotic
- cell wall has glucan and chitin
- cell membrane has ergosterol (other “-sterols”)
Difference between mycoses & mycotoxins
- mycoses: grows inside host
- mycotoxins: grows outside the host
Importance of mycoses
- diagnosed late or misdiagnosed b/c signs are non-specific or insuff. culture sensitivity
- immunosupp. Patients get disseminated mycoses
- long term abx can eliminate/reduce bacterial load
- tx challenging
What mediums can fungi grow on as a mold or yeast
SDA
Fungi that affect skin/SQ
- Microsporum spp.
- Trichophyton spp.
- malassezia pachydermatis
- sporothrix schenkii
Fungi that infect systemically
- histoplasma capsulatum
- blastomyces dermatidis
- coccidioides immitis
- cryptococcus neoformans
Opportunistic fungi
- aspergillus fumigatus
- candida albicans & auris
Dermatomycoses is also known as
Ring worm
What are the trichophyton that cause ring worm in large animals?
- T. Verrucosum (cattle)
- T. Rubrum (humans)
- T. Mentagrophytes (horses)
Microsporum canis
- zoophilic dermatophyte
- affects small animals
Non-dermatophytes spp.
Malassezia pachydematis & M. Nana
Dermatophytes is grown on
DTM
How to dx dermatophytes
- wood’s lamp (only for M. Canis)
- hair/skin specimen microscopy
- culture and ID
- KOH mount
KOH mount
- not really used, only by experts
- look for ectothrix formation
- look for arthrospores surrounding/on hair
Malassezia & otitis/dermatitis
- normal flora of man and animals
- M. Pachydermatis & M. Nana found in animals
- commensalistic in normal subjects
- disease caused by host related factors
- elephant skin
Sporotrichoisis
- agent: S. schenkii (dimorphic)
- found in N & S America
- SQ invasive mycosis
- aka: rose-gardener’s disease
Sporothrix schenkii microscopic characteristics
- colonies are small and white w/o cottony aerial hyphae
- later colonies become moist, velvety, and darkly
- septate, thin, branching, hyphae @ right angles
- conidia are pear shaped in clusters
- cigar bodies
