Unit 7 textbook + Lab book questions Flashcards
What is the primary purpose of microbiology examinations?
the identification of bacterial pathogens
What are the two types of dermatophyte test media?
Standard dermatophyte test media (DTM) and Standard Sabouraud dextrose agar
Partial hemolysis that creates a narrow band of greenish or slimy discoloration around the bacterial colony us referred to as?
alpha hemolysis
Bacteria are small ____ cells.
prokaryotic
Bacteria have specific requirements, in what areas?
temperature, pH, oxygen tension, and nutrition
What type of fungal organisms have no known sexual stages?
Deuteromycetes
The dermatophytes comprise of different organisms in the taxonomic genera?
Microsporum and Trichophyton
3 common Dermatophytes?
Microsporum canis, Microsporum gypseum, and trichophyton mentagrophytes
Dermatophytes are classified by what habitats?
Anthropophilic, zoophilic, geophilic
Anthropophilic live on?
people
Zoophilic live on?
animals
Geophilic live in?
existing as freeliving saprophytes in the soil
What is one test that us used when Dermatophyptes are found on the hair shaft?
- pluck hairs
- place on slide with 1 - 2 gtt of 10% KOH
- After 2-10 min small globular arthrospores are visible on the shaft
visualized microscopically
Another Dermatophyte testing is using a Wood lamp , what is it?
an ultraviolet light source that may be used to screen suspect lesions for dermatophyte infection, but results may be ambiguous
50% success - positive result is a clear, apple green glow
What can you use to culture dermatophytes?
- ## most common is DTM - which contains an indicator that turns red in the presence of most dermatophytes.
What media is available to culture dermatophytes using DTM in tube format?
faster - RSM - rapid sporulation medium
faster - ESM - enhanced sporulation medium - both have color indicators and accerlate formation of macroconidia for ID
slower - Sabouraud dextrose agar - also promotes early formation of macroconidia but no color change
How do you collect samples for Dermatophytes?
clean the skin lesion to remove some of the surface contamination and collect specimens from the lesion periphery, leave at room temp. - observe daily, at first sign, wet prep using tape and lactophenol cotton blue stain - on slide
Test results for DTM are what color
positive - red in DTM
Teal in ESM or other media
support by microscope exam
Fungal cultures, non-dermatophytes are plated on what medium?
on blood agar or sabouraud dextrose agar
What is Bacillus anthracis?
a bacterium that causes amthrax in animals, humans, cattle, sheep, and guinea pigs
Pasturella is?
a genus of Gram-negative, facultatively anaerobic bacteria.
