Summary of biochemical approaches and techniques discussed Abbreviations: API, analytical profile index; AST, antimicrobial susceptibility testing; ID, identification; MALDI, matrix-assisted laser desorption ionization; MS, mass spectrometry.
Approach | Isolation Required | Growth Required for ID | Examples | Description of Approach |
|---|---|---|---|---|
| Single-tube tests | Yes | Yes | Christensen’s urea agar, Simmons’ citrate medium | Each tube needed requires inoculation, 1 reaction per tube, may need 8–20 different tubes for identification |
| Multitest tube systems | Yes | Yes | Durham tube, Kligler’s iron agar, triple sugar iron agar, R-B media | One inoculation per system, more than 1 reaction possible in each tube |
| Rapid (spot) tests | Yes | No | Catalase, oxidase, indole production | Individual colony mixed with a reagent, reaction develops within seconds, based on preformed enzyme |
| Multitest kits | Yes | Yes | PathoTec, API, AuxoTab, Enterotube, Micro-Media | Manual inoculation of trips or tubes containing small compartments of media, able to test for ≥8 reactions in each kit |
| Automated growth-based systems | Yes | Yes | Vitek, MicroScan, Phoenix, Sensititre | Single inoculum device loaded onto small-to-large capacity machines, capable of ID and AST at the same time |
| Mass spectrometry | Yes/no | No | Vitek MS, MALDI Biotyper | Single colony inoculated on plate, laser fragments cell into peptidic fragments, AST on separate automated instrument |