Table 1.
Bacteria quantification methods
| Method | Range of detection | Time to obtain results | Distinguishes live vs. dead | Persisters included in quantification | Applications | Equipment needed | Count affected by minor bacterial clumps |
|---|---|---|---|---|---|---|---|
| CFU count |
Unlimited |
Days |
Yes |
Yes |
Determination of absolute bacterial number |
None |
Yes |
| Absorbance |
108–1010 bacteria/mL |
Immediate |
No |
No |
Follow growth curves |
Spectrophotometer or plate reader |
No |
| Microscopy |
Unlimited |
Minutes |
Yes, with staining |
No |
Determination of absolute bacterial number |
Microscope |
No |
| Flow cytometry |
> ~5000 |
Minutes |
Yes, with staining |
Yes, if not below detection |
Determination of absolute bacterial number |
FACS |
Yes |
| MBRT [2] |
> ~107 |
Hours |
Yes |
No (metabolically quiescent cells missed) |
MIC and MAC determination |
Spectrophotometer |
No |
| SGT | Unlimited | Hours | Yes | Yes | HTS, persister Quantification | Plate reader | No |