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
Deaminase test uses is useful in differentiation of
Proteus
Morganella
Providencia
This test determines whether an organism can use sodium citrate as a sole carbon source
Citrate utilization
What is the primary function of the LIA slant
deamination or decarboxylation of lysine.
Can be used in screening for stool pathogens
LIA slant
This test determines whether the organism is capable of using sodium malonate as its sole carbon source
Malonate test
Determined by microscopic examination of bacteria or observing growth in a semi-solid medium
Motility
Oxidase is helpful in differentiating between?
Enterobacteriaceae
Pseudomonads
Neisseria
This test is used to determine whether a microorganism can hydrolyze urea
Urease test
The resulting alkaline pH from the hydrolysis of urea is indicated by what?
Bright pink color
pH-based reactions, enzyme-based reactions, utilization of carbon sources, visual detection of bacterial growth, and detection of volatile fatty acids are principle of what?
Principles of Identification
