Microbiology (BIOL 201) Gram Stain and Biochemical Tests Pathogen ID Practice Problems
School: University of Texas at Austin
Course: Microbiology (BIOL 201)
Document type: Practice Problems

Overview
A lab-practical practice set that trains you to identify likely pathogens using Gram stain, morphology, and quick biochemical tests in a consistent decision flow. This note helps students review Gram-positive vs Gram-negative decision points, Staph vs Strep with catalase and coagulase, hemolysis patterns and common clinical clues with clear examples and study prompts.

What this document covers
- Gram-positive vs Gram-negative decision points
- Staph vs Strep with catalase and coagulase
- hemolysis patterns and common clinical clues
- enteric test logic (lactose fermentation oxidase indole)
- building a step-by-step ID flowchart

How to use it
1. work through 15 case cards and name the most likely organism group
2. create a one-page ID flowchart you can follow under time pressure
3. for each case list the 2 confirmatory tests you would order next
4. practice interpreting 10 rapid test panels (catalase coagulase oxidase lactose)
5. run a 5-minute recall drill of test-to-meaning pairs

Common mistakes to avoid
- jumping to species-level ID without enough evidence
- mixing up catalase vs coagulase meaning
- ignoring specimen source and clinical context
- misreading lactose fermentation or oxidase results
- forgetting that similar results can indicate multiple organisms