TABLE 2.
MIC values (μg/ml) observed for P. salmonis strains in nutrient broth (Austral-SRS) and the defined medium (CMMAB).
| LF-89 | CGR02 | EM-90 | Ps12201A | ||||||||||||||
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| MIC range | Phenotype | MIC range | Phenotype | MIC range | Phenotype | MIC range | Phenotype | ||||||||||
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| Drug family | Antibiotic name | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB | Austral-SRS | CMM-AB |
| Tetracyclines | Tetracycline | 0.16–0.32 | 0.02–0.08 | S | S | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| Oxytetracycline§ | 0.16–0.32 | 0.02–0.08 | S | S | 0.08–0.32 | 0.02–0.08 | S | S | 0.08–0.16 | 0.02–0.16 | S | S | 0.08–0.16 | 0.02–0.08 | S | S | |
| Fluoroquinolone, quinolone antibiotic | Flumequine§ | 0.32–0.64 | 0.08–0.16 | S | S | 0.08–0.64 | 0.02–0.16 | S | S | 0.04–0.08 | 0.02–0.04 | S | S | 0.04–0.16 | 0.02 | S | S |
| Oxolinic acid | 0.32 | 0.04–0.08 | S | S | 0.32–0.64 | 0.08–0.16 | S | S | 0.04–0.16 | 0.02–0.16 | S | S | 0.04–0.08 | 0.02 | S | S | |
| Macrolide antibiotic | Erythromycin | 1.6–6.4 | 12.5–25 | S | R | 1.6–12.5 | 3.12–12.5 | S | I | 0.4–1.6 | 3.12–12.5 | S | I | 0.8–1.6 | 12.5–25 | S | R |
| Phenicol antibiotic | Chloramphenicol | 0.16–0.64 | 0.16–0.32 | S | S | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND |
| Florfenicol§ | 0.08–0.32 | 0.32–0.64 | S | S | 0.04–0.64 | 0.08–1.28 | S | S | 0.08–0.32 | 0.312–1.25 | S | S | 0.08–0.32 | 0.32–1.28 | S | S | |
| Peptide antibiotic | Polymyxin B | 6.25–12.5 | 12.5–25 | I | R | 12.5 | 6.25–12.5 | R | I | 12.5 | 25–125 | R | R | 12.5–25 | 12.5–50 | R | R |
| Glycopeptide antibiotic | Vancomycin* | >1,000 | >1,000 | R | R | >1,000 | >1,000 | R | R | >1,000 | >1,000 | R | R | >1,000 | >1,000 | R | R |
| Beta-lactam, cephalosporin | Ampicillin | 0.1–0.8** | 200–400 | S | R | 0.1–0.4** | 125–250 | S | R | 0.08–0.4** | 31.2 | S | R | 0.08–0.4** | 31.2–250 | S | R |
| Penicillin G | 0.4–0.8** | 25–200 | S | R | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | |
| Ceftazidime | >1,000** | >1,000** | R | R | >1,000** | >1,000** | R | R | >1,000** | >1,000** | R | R | >1,000** | >1,000** | R | R | |
| Aminoglycoside antibiotic | Streptomycin | 6.25–12.5 | 50–100 | I | R | 3.12–6.25 | 100–400 | S | R | 6.25–12.5 | 400 | I | R | 6.25 | 100–400 | S | R |
| Spectinomycin | 6.25–25 | 12.5–50 | I | R | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | ND | |
| Diaminopyrimidine antibiotic | Trimethoprim | 125 | 250 | R | R | 62.5–125 | 500 | R | R | 62.5–125 | 500 | R | R | 125 | 250–500 | R | R |
| Rifamycin antibiotic | Rifampicin | 1.6 | 0.8–1.56 | S | S | 1.6 | 0.8–1.6 | S | S | 0.8–1.6 | 0.8–1.6 | S | S | 0.8–1.6 | 0.8–1.6 | S | S |
Bacteria were considered resistant (R) to an antibiotic if MIC > 10 μg/ml; if not, they were labeled as susceptible (S). If MIC range was around the breakpoint of the resistant phenotype, then an intermediate range (I) of susceptibility was defined.
§ Antibiotics used in aquaculture.
*Antibiotic for Gram-positive bacteria.
**Suboptimal growth compared to the control.