TABLE 2.
Association of resistance to amikacin with resistance to other antimicrobials for isolates of Staphylococcus pseudintermedius (n = 422), expressed as odds ratios derived by logistic regression analysis
| Antimicrobial agenta | No. (%) of isolates that were: |
Odds ratio (95% CI) | P | |
|---|---|---|---|---|
| Amikacin susceptible | Amikacin resistant | |||
| Oxacillin | ||||
| S | 316 (93) | 22 (7) | 1 (NAb) | |
| R | 53 (63) | 31 (37) | 8.4 (4.5–15.6) | <0.0001 |
| Chloramphenicol | ||||
| S | 325 (92) | 30 (8) | 1 (NA) | |
| R | 44 (66) | 23 (34) | 5.7 (3.0–10.6) | <0.0001 |
| Clindamycin | ||||
| S | 298 (96) | 11 (4) | 1 (NA) | |
| R | 71 (63) | 42 (37) | 16.0 (7.6–34.0) | <0.0001 |
| Doxycycline | ||||
| S | 251 (95) | 13 (5) | 1 (NA) | |
| R | 117 (75) | 39 (25) | 6.4 (3.3–12.5) | <0.0001 |
| Enrofloxacin | ||||
| S | 328 (95) | 18 (5) | 1 (NA) | |
| R | 41 (54) | 35 (46) | 15.6 (8.1–29.9) | <0.0001 |
| Erythromycin | ||||
| S | 299 (96) | 11 (4) | 1 (NA) | |
| R | 68 (62) | 42 (38) | 16.8 (8.2–34.3) | <0.0001 |
| Gentamicin | ||||
| S | 348 (100) | 0 (0) | 1 (NA) | |
| R | 21 (28) | 53 (72) | Inestimablec | <0.0001c |
| Marbofloxacin | ||||
| S | 331 (92) | 27 (8) | 1 (NA) | |
| R | 37 (59) | 26 (41) | 8.6 (4.6–16.3) | <0.0001 |
| Rifampin | ||||
| S | 359 (88) | 48 (12) | 1 (NA) | |
| R | 8 (62) | 5 (38) | 4.7 (1.5–14.9) | 0.0093 |
| Trimethoprim-sulfonamide | ||||
| S | 309 (96) | 14 (4) | 1 (NA) | |
| R | 58 (60) | 39 (40) | 14.8 (7.6–28.9) | <0.0001 |
a
S, susceptible; R, resistant.
b
NA, not applicable (reference category).
c
Inestimable because of complete separation (i.e., no isolate resistant to amikacin was susceptible to gentamicin); the P value was derived from the chi-square test with continuity correction.