Microbiology Quick Reference
| Test | Positive QC | Negative QC | Uses |
|---|---|---|---|
| Catalase | Staphylococcus spp. | ||
| Coagulase | S. aureus | Other Staphylococcus | |
| Staphaureux (Latex agglutination) | |||
| PYR | S. lugdunensis |
Staphylococcus species
Staphylococcus aureus
- GPC clusters
- Catalase +
- Coagulase +
- Staphaureux +
If coagulase/Staphaureux negative, then CoNS:
- S. lugdunensis: PYR +
- S. saprophyticus (females 12-60): Novobiocin resistant
- Others: S. epidermidis, other CoNS
Streptococcus species
- GPC pairs & chains
- Catalase -
Lancefield grouping mainly used for ID
| Lancefield Grouping | Organism | Features | Clinical Relevance |
|---|---|---|---|
| Group A | S. pyogenes |
|
iGAS |
| Group B | S. agalactiae |
|
|
| Group D | S. bovis | ||
| Enterococcus
|
|||
| Group C | Streptococcus dysgalactiae subsp equisimilis | Beta-heme | Normally commensal |
| Group G | |||
| S. pneumoniae |
|
||
| Viridans Streptococci |
Catalase
Oxidase
PYR