Lab Quiz 4 revised Flashcards
33: what media is used in skin culture
Mannitol salt agar plate
33: What ingredient makes skin media selective and how is it selective
contains 7% salt which allows only salt tolerant organisms to grow
33: what ingredient make skin media differential and how is it
mannitol sugar
organisms that ferment mannitol grow yellow agar
non fermenting organisms remains red agar
33: what tests are used to determine if colony is a staph species
- gram + cocci
- catalase +
33: what test are used to identify staph species isolated
- mannitol fermentation
- coagulate
33: what is the reaction of coagulase
coagulase enzyme metabolizes fibrinogen into a fibrin clot
33: appearance of coagulase result
- liquid media: -
- clot formed: +
33: what species of staph produces coagulase
staph aureus
33: phenol red fermentation test explained and results
- sugar fermented, acids produced, ph decreases, phenol red changes from red to yellow
- yellow: +
- red: -
- phenol red indicator
35: what media are used for the mouth culture
- Mitis-salivating agar
- chrom agar candida
35: purpose of MSB agar
only allows growth of strep species which are prevalent in the mouth
35: How is MSB selective
crystal violet and telluride inhibit gram + and gram - growth excerpt for streptococcus
35: How is MSB differential
- contains tryptan blue and sucrose
- strep species blue black in color
- differences in colony appearance identify species
35: purpose of chrom agar candida
isolation of candida species from saliva
35: how is chrom agar selective
chloramphenicol inhibits all gram + and gram - bacterial which allows candida yeast to grow
35: how is chrom agar differential
chromagenic granules metabolized differently by different species and appear different colors on agar
35: what species is commonly isolated on chrom agar and what is the appearance
- candida albicans
- apple green
35: what strep species is responsible for dental carie’s
strep mutans
35: what is the appearance of the 4 major types of strep on MSB agar
strep mitis: small, blue
enterococcus: small, black
strep salivarius: large, blue, gumdrop
strep mutans: blue, glass or burnt sugar
35: appearance of yeast cells under microscope
rain droplet like colonies with green tint
36: what medias are used for urine culture
- 5% sheep blood agar
- MacConkey agar
36: purpose of 5% sheep blood agar
- good rich media that is non selective
- determine total bacterial count per ml of urine
36: purpose of Macconkey agar
- determine gram - bacteria count per ml of urine which is used to determine UTIs
36: how is macconkey agar selective
crystal violet and bile salts inhibit gram + growth and allow only gram - growth