TABLE 1.
Comparison between the bioluminescent inducible and constitutive expression systems for the detection of antimicrobial action powera
| Antibiotic | Low concn (ng/ml) | % from water blank | High concn (ng/ml) | % from water blank |
|---|---|---|---|---|
| RN4220/pTOO24 | ||||
| Rifampin | 1.9 | 40.0 | 64.0 | 0.2 |
| Tetracycline | 25.6 | 35.9 | 64.0 | 3.3 |
| Chloramphenicol | 640.0 | 36.2 | 3200.0 | 5.2 |
| Ampicillin | 128.0 | 98.0 | 640.0 | 15.3 |
| Cefotaxime | 128.0 | 75.0 | 640.0 | 19.5 |
| Norfloxacin | 128.0 | 85.3 | 3200.0 | 8.3 |
| Ciprofloxacin | 128.0 | 74.4 | 3200.0 | 29.2 |
| Spiramycin | 128.0 | 91.7 | 3200.0 | 26.4 |
| Erythromycin | 128.0 | 37.1 | 640.0 | 1.4 |
| Trimethoprim | 128.0 | 81.0 | 3200.0 | 22.3 |
| Sulfadiazine | 128.0 | 80.6 | 3200.0 | 96.7 |
| RN4220/pCSS810 | ||||
| Rifampin | 64.0 | 14.5 | 640.0 | 11.9 |
| Tetracycline | 64.0 | 21.7 | 640.0 | 8.4 |
| Chloramphenicol | 640.0 | 81.9 | 3200.0 | 61.7 |
| Ampicillin | 128.0 | 100.8 | 640.0 | 76.3 |
| Cefotaxime | 128.0 | 90.6 | 640.0 | 65.1 |
| Norfloxacin | 128.0 | 85.2 | 3200.0 | 39.8 |
| Ciprofloxacin | 128.0 | 70.3 | 3200.0 | 44.7 |
| Spiramycin | 128.0 | 85.9 | 3200.0 | 49.3 |
| Erythromycin | 128.0 | 56.4 | 640.0 | 19.2 |
| Trimethoprim | 128.0 | 90.1 | 3200.0 | 33.7 |
| Sulfadiazine | 128.0 | 45.4 | 3200.0 | 51.3 |
The S. aureus indicator strains RN4220/pTOO24 and RN4200/pCSS810 were freshly cultivated for the measurement and diluted. The cells were added on the wells of a white microtitration plate, preincubated with antibiotic for 90 min at room temperature, induced by 1 μM antimonite and measured for their bioluminescence immediately after the dispension of d-luciferin at +90 min (and repeated after 30 min, resulting in a total assay time of 210 min). The table shows results from low and high concentrations of each particular antibiotic. The results shown are means of three parallel measurements, and the coefficients of variation are between 2 and 7%.