Table 1. Selection conditions.
| Antibiotic | Concentration (μg ml−1) | Code | Class | Number of colonies |
|---|---|---|---|---|
| Ampicillin | 16 | AMP | β-Lactam/penicillin | 660 |
| Amoxicillin | 16 | AMX | β-Lactam/penicillin | 500 |
| Carbenicillin | 64 | CAR | β-Lactam/penicillin | 1,100 |
| Piperacillin | 16 | PIP | β-Lactam/penicillin | 800 |
| Ceftazidime | 1 | CTZ | β-Lactam/cephalosporin | 350 |
| Amikacin | 16 | AMK | Aminoglycoside | 220 |
| Gentamicin | 8 | GEN | Aminoglycoside | 40 |
| Spectinomycin | 32 | SPC | Aminoglycoside | 330 |
| Azithromycin | 16 | AZI | Macrolide | 120 |
| Erythromycin | 100 | ERY | Macrolide | 200 |
| Tetracycline | 4 | TET | Tetracycline | 100 |
| Chloramphenicol | 6 | CAM | Phenicol | 30 |
| Rifampicin | 16 | RIF | Rifamycin | 210 |
| Trimethoprim | 4 | TMP | Benzylpyrimidine | 2,000 |
| Sulfamethoxazole/trimethoprim | 32:4 | SXT | Sulfonamide/dihydrofolate reductase inhibitor | 1,500 |
| Total | 8,160 |
AMK, amikacin; AMP, ampicillin; AMX, amoxicillin; AZI, azithromycin; CAM, chloramphenicol; CAR, carbenicillin; CTZ, ceftazidime; ERY, erythromycin; GEN, gentamicin; PIP, piperacillin; RIF, rifampicin; SPC, spectinomycin; SXT, sulfamethoxazole/trimethoprim; TET, tetracycline; TMP, trimethoprim.