Table 1.
Antimicrobial resistance of Enterococcus faecalis and Enterococcus faecium in bulk tank milk samples from four dairy companies
| No. (%) of Antimicrobial-Resistant Enterococci Isolates, by Company | |||||
|---|---|---|---|---|---|
| A | B | C | D | Total | |
| Antimicrobials | (n = 132) * | (n = 53) | (n = 58) | (n = 95) | (n = 338) |
| β-Lactams | |||||
| Penicillin | 1 (0.8) a,b | 0 (0.0) a,b | 3 (5.2) b | 0 (0.0) a | 4 (1.2) |
| Ampicillin | 2 (1.5) | 1 (1.9) | 0 (0.0) | 0 (0.0) | 3 (0.9) |
| Glycopeptides | |||||
| Vancomycin | 0 (0.0) a | 2 (3.8) b | 0 (0.0) a,b | 0 (0.0) a,b | 2 (0.6) |
| Macrolides | |||||
| Erythromycin | 43 (32.6) a | 23 (43.4) a,b | 41 (70.7) c | 49 (51.6) b | 156 (46.2) |
| Tetracyclines | |||||
| Tetracycline | 96 (72.7) a,b | 32 (60.4) a | 51 (87.9) c | 69 (72.6) a,b | 248 (73.4) |
| Doxycycline | 69 (52.3) | 24 (45.3) | 34 (58.6) | 41 (43.2) | 168 (49.7) |
| Fluoroquinolones | |||||
| Ciprofloxacin | 3 (2.3) a | 5 (9.4) b | 2 (3.4) a,b | 3 (3.2) a,b | 13 (3.8) |
| Phenicols | |||||
| Chloramphenicol | 16 (12.1) a | 16 (30.2) b | 33 (56.9) c | 21 (22.1) a,b | 86 (25.4) |
| Ansamycins | |||||
| Rifampin | 29 (22.0) | 12 (22.6) | 10 (17.2) | 20 (21.1) | 71 (21.0) |
* n = number of E. faecalis and E. faecium isolated from bulk tank milk, by company. Values within a column not having the same subscript letter (a, b, c) differ significantly (p < 0.05).