Question | Answer |
What are the possible outcomes of the Lysine Iron Agar test and what do they indicate about the organisms being observed? | Purple Slant/Purple butt: + for decarboxylation - K/K *anaerobic
- H2S production may be seen
Purple Slant/Yellow butt: - for decarboxylation - K/A - fermentation of glucose only
Burgundy Slant/Yellow butt: + for deamination - A/A *aerobic |
What substances are produced by the organisms in the LIA test? | K/K - carboxyl group (-COOH) - produces cadaverine and CO2
A/A - amine group (-NH2)
K/A - no reaction |
Why is H2S production not the most reliable indicator in biochemical testing methods? | Certain species of bacteria may have different strains that may or may not produce H2S when tested |
What could be a potential outcome of incubating a test in a CO2 environment? | This could alter the pH of the environment, which will alter test results and lead to misidentification |
What part of the Ornithine test do we look at for interpretation? | Color change in the butt ONLY:
- Positive = purple
- Negative = yellow |
Which biochemical tests would be classified as deamination reactions? | - LIA
- Phenylalanine |
What organisms can the Oxidase test help us to identify? What would be a good test to run in order to identify between them? | -Pseudomonas, Neisseria
- Cetrimide |
When running an OF test, which container indicates the presence of acid production? | Fermentation reaction:
- acid reaction in covered and uncovered tubes (both tubes Y)
- acid reaction in covered tube only (covered tube Y, uncovered G)
Oxidation reaction:
- acid reaction in uncovered tube only (uncovered tube Y, covered tube G) |
In the OF test, can a negative result be given? | No - the organism being observed can only be identified as a "non-utilizer", meaning that it might not utilize the specific nutrient source in that media |
What is the main difference between the Kligler Iron Agar and the Triple Sugar Iron Agar? | The TSI Agar contains an extra nutrient source (sucrose), which helps to identify slow lactose fermenters better than the KIA |