5.14 Lab Flashcards
diagnostic strategies for fungal infections
- Direct demonstration
- culture
- immunological
- toxins
what is direct demonstration diagnostics for fungus?
Large size helps; 10% KOH wet mount; Gram (yeasts); Silver (tissue)
what is diagnosis by culture for fungus?
Sabouraud dextrose agar
Yeasts: 2-7 days
Molds/filamentous fungi: 2 days to weeks
what is immunological diagnosis for fungii?
Agar Gel Immuno-Diffusion; ELISA
how do we diagnose fungii via toxins?
Mycotoxins (ELISA, chromatography)
how long does isolation of fungi take?
lab will only be able to send an official, final report 1 month after
-can give updates of their suspicions before this
What can we do when we only see hyphae and cannot identify the isolate?
PCR
MADLI-TOF but not yet optimized for fungii - fails in challenging cases
sequencing - very useful for mycology
- How common is antifungal susceptibility testing?
rare
what can you do in clinic for a dog with suspected ringowrm?
Wood’s lamp: M. canis fluoresces (~50%strains)
>Not the other dermatophytes!
what is Wood’s lamp?
M. canis fluoresces (~50% strains)
>but if negative, doesnt mean its not ringowrm! could be a different strain!
does cryptococcus form a morula?
no
What is Prototheca and what does it cause in animals?
Yeast
in Cats:
* Firm, nonpruriginous, single to multiple, cutaneous-subcutaneous nodules, or masses, with scabs to an ulcerated aspect
* Present predominantly on the forehead, nose, base of the tail, pinnae, and distal aspects of the limbs
- Similar lesions in dogs
- Associated with bovine mastitis
- Zoonosis? some species yes, but not well understood
How can DNA sequencing assist with precise diagnosis?
Importance of pathogen identification at the species level
some species will be damgerous/zoonotic while others that are closely related are not - can save an animal from euthanasia
is fungel identification easy? how long is treatment?
- Fungal identification is difficult
- Treatment is long!
great alternative to fungal culture for ID?
Sanger sequencing
