Table 2.
Average MICs for Salmonella Typhimurium and Salmonella Newport isolates used in this study
| Breakpoint or isolate group | MIC (μg/ml)a |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| AMP | CEF | CRO | FEP | AMK | GEN | TET | CHL | CIP | TZP | |
| Breakpoint | 32 | 32 | 4 | 32 | 64 | 16 | 16 | 32 | 4 | 128 |
| Isolate group | ||||||||||
| Pretreatment | 1,836 (418) | ≥2,000 (0) | 52 (5) | 91 (33) | 13 (4) | 6 (3) | 79 (19) | 150 (40) | 0.3 (0) | 400 (0) |
| Posttreatment | ≥2,000 (0) | ≥2,000 (0) | 155* (84) | 128* (0) | 18* (5) | 6 (2) | 107* (23) | 157 (43) | 0.3 (0) | 386 (36) |
| Posttreatment with CRO pressure | ND | ND | 162* (86) | 69 (28) | ND | 6 (2) | 112* (35) | 186 (46) | ND | 73* (139) |
a
Values represent means (standard deviations) from 7 strains utilized in this study. AMP, ampicillin; CEF, cephalothin; CRO, ceftriaxone; FEP, cefepime; AMK, amikacin; GEN, gentamicin; TET, tetracycline; CHL, chloramphenicol; CIP, ciprofloxacin; TZP, piperacillin-tazobactam. Statistical comparisons of MIC data were made using the Kruskal-Wallis test with Dunn's post hoc test where appropriate. *, P < 0.05; ND, not determined.