Table 1.
Susceptibility of Staphylococcus spp. isolated from milk samples of dairy cows with mastitis from municipalities of the Zona da Mata Region, Minas Gerais, Brazil to 12 antimicrobial agents, 2010–2011
| Antimicrobial | Zone diameter cutoff (mm) | S. aureus | CoNS | ||||||
|---|---|---|---|---|---|---|---|---|---|
| S | I | R | S (%) | I (%) | R (%) | S (%) | I (%) | R (%) | |
| Ampicillin | ≥29 | – | ≤28 | 17 (23.9) | NA | 54 (76.1) | 0 (0.0) | NA | 8 (100.0) |
| Cephalothin | ≥18 | 15–17 | ≤14 | 71 (100.0) | 0 (0.00) | 0 (0.00) | 8 (100.0) | 0 (0.0) | 0 (0.0) |
| Ceftiofur | ≥21 | 18–20 | ≤17 | 71 (100.0) | 0 (0.00) | 0 (0.00) | 7 (87.5) | 1 (12.5) | 0 (0.0) |
| Clindamycin | ≥21 | 15–20 | ≤14 | 61 (85.9) | 0 (0.00) | 10 (14.1) | 4 (50.0) | 1 (12.5) | 3 (37.5) |
| Erythromycin | ≥23 | 14–22 | ≤13 | 58 (81.7) | 3 (4.2) | 10 (14.1) | 4 (50.0) | 1 (12.5) | 3 (37.5) |
| Enrofloxacin | ≥23 | 17–22 | ≤16 | 70 (98.6) | 1 (1.4) | 0 (0.0) | 8 (100.0) | 0 (0.0) | 0 (0.0) |
| Gentamicin | ≥16 | 13–15 | ≤12 | 69 (97.2) | 0 (0.0) | 2 (2.8) | 3 (37.5) | 1 (12.5) | 4 (50.0) |
| Oxacillin | ≥18 | – | ≤17 | 69 (97.2) | NA | 2 (2.8) | 2 (25.0) | NA | 6 (75.0) |
| Penicillin | ≥29 | – | ≤28 | 15 (21.1) | NA | 56 (78.9) | 0 (0.0) | NA | 8 (100.0) |
| Sulfonamide | ≥17 | 13–16 | ≤12 | 59 (83.1) | 7 (9.9) | 5 (7.0) | 3 (37.5) | 1 (12.5) | 4 (50.0) |
| Tetracycline | ≥19 | 15–18 | ≤14 | 17 (23.9) | 0 (0.00) | 54 (76.1) | 0 (0.0) | 0 (0.0) | 8 (100.0) |
| Trimethoprim/Sulfamethoxazole | ≥16 | 11–15 | ≤10 | 17 (23.9) | 10 (14.1) | 44 (62.0) | 0 (0.0) | 0 (0.0) | 8 (100.0) |