Chapter 9: Biochemical identification of Gram-Negative Bacteria Flashcards
Biochemical testing is based on what?
Phenotypic characteristics
Used of antibodies to detect specific antigens located on the bacterial surface
Serotyping (serogrouping)
The most important carbohydrate determination
Lactose Utilization
Can be used to differentiate lactose fermenting (LF) bacterial species from nonlactose fermenters (NLFs)
Lactose Utilization
What two enzymes are required for lactose degradation
Beta-galactoside permease and Beta-galactosidase
What enzymes can transport lactose through a cell wall?
Beta-galactoside permease
What enzyme can break lactose to yield subunites?
Beta-galactosidase
Known as late or delayed LFs(dLFs)
Bacterial species that lack permease but have beta-galactosidase
Determine the ability of a bacteria to ferment a specific carbohydrate incorporated in the medium
Oxidation-fermentation (O/F) Tests
Asaccharolytic
Do not utilize carbohydrates
What pathway is fermentation?
glycolysis pathway
What is the end product of glycolysis?
Acid or acid with gas
What pathway is oxidation?
Glycolysis pathway
Does oxidation produce weak or strong acid?
weak acid that is neutralized by alkaline reactions from peptones
What is the description of O/F basal media?
Lower concentration of peptones
What is the purpose of O/F basal media
Help classify as oxidizer or fermenter and detects small amounts of acids
What does Kligler Iron Agar contain?
glucose and lactose and detects fermentation
For KIA (kligler iron agar) what does yellow indicate?
Acidic (below 6.8)
For KIA what does red indicate?
alkaline (above 6.8)
If there is a black color to the kligler iron agar what does it detect?
Production of hydrogen sulfide (H2S)
ALK/ALK or K/K means?
No fermentation
What is the purpose of the Orthpo-Nitrophenyl-beta-D=Galactopuranoside test (ONPG)
To determine if an organism found to be a dLF but is a true NLF
What occurs in the Embden-Meyerhof pathway?
Glucose Metabolism
This test the presence of enzymes capable of removing carboxyl group from certain amino acids
Amino acid utilization decarboxylase and dihydrolase