Laboratory Diagnosis Of Bacteria Flashcards
“In vivo”
In the body
“In vitro”
In the lab/artificial environment
Enriched non selective media
Contain nutrients that support growth of most organisms (ex. Blood agar)
Selective and differential media
Enhances the growth of a particular organism from a mixture of organisms by using nutrient specificity (or suppressing growth of unwanted organisms) (ex. MacConkey agar)
MacConkey Agar
Selective agar for growth of gram negative bacteria - also distinguishes between lactose fermenting and non-lactose fermenting
Lactose +
Pink MacConkey agar results of lactose fermenting bacteria
Lactose -
Clear MacConkey agar results - non lactose fermenting
Blood agar differentiation
Differentiates ability to hemolyze RBC
Alpha-hemolysis
Partial hemolysis -greenish colonies
Beta-hemolysis
Complete hemolysis - class around colonies
Gamma-hemolysis
No hemolysis -no change in media
Agar for Esherichia coli 0157
MacConkey sorbitol agar
Buffered charcoal yeast extract agar
Recovery of legionella and nocardia
Fastidious
Complex nutritional requirements
Non fastidious
Simple nutritional requirements
Strict aerobes
Require O2 for growth
Strict anaerobes
Will not tolerate O2
Facultative anaerobes
Aerobes that can grow anaerobically
Aerotolerant anaerobes
Anaerobes that can tolerate O2
Microaerophilic
Prefers reduced O2
Capnophilic
Prefers increases CO2
Pseudomonas aeruginosa
Strict aerobe
Bacteroides fragilis
Strict anaerobes
Gram stain procedure
Fix specimen. Crystal violet stain. Iodine treatment. Decolarizer. safranin stain.
