Table 2.
MIC 90 (mg/L), antimicrobial susceptibility (%S) and statistically significant changes in susceptibility among resistant pathogen phenotypes
| Pathogen | Antimicrobial | MIC 90 | %S | Significance a |
|---|---|---|---|---|
| Gram-positive | ||||
| E. faecium, VRE (n = 18 [0/18]) | AMC | ≥16 | 16.7 | N.S. |
| AMP | ≥32 | 16.7 | N.S. | |
| LZD | 2 | 100 | - | |
| TIG | 0.25 | 100 | - | |
| VAN | ≥64 | 0.0 | - | |
| S. aureus, MRSA (n = 631 [77/554]) | LEV | 32 | 13.2 | N.S. |
| LZD | 2 | 100 | - | |
| MIN | 0.5 | 93.5 | p < 0.001 (−) | |
| PEN | ≥16 | 0.0 | - | |
| TIG | 0.25 | 100 | - | |
| VAN | 1 | 100 | - | |
| S. pneumoniae, PRSP (n = 32; 31b) | AMP | 8 | 0.0 | - |
| AZI | ≥128 | 19.4 | N.S. | |
| CRO | 2 | 6.3 | N.S. | |
| CLA | ≥128 | 19.4 | N.S. | |
| CLI | ≥128 | 32.3 | p < 0.01 (−) | |
| ERY | ≥128 | 19.4 | N.S. | |
| LEV | 2 | 96.9 | N.S. | |
| LZD | 1 | 100 | - | |
| MER | 1 | 96.9 | N.S. | |
| MIN | ≥16 | 18.8 | N.S. | |
| PEN | 4 | 0.0 | - | |
| VAN | 0.5 | 100 | - | |
| Gram-negative | ||||
| E. coli, ESBL (n = 275 [17/258]) | AMK | 8 | 90.5 | p < 0.001 (−) |
| AMC | 32 | 36.7 | p < 0.001 (−) | |
| AMP | ≥64 | 0.0 | - | |
| CFP | ≥64 | 4.7 | N.S. | |
| CRO | ≥128 | 0.0 | - | |
| IMP | 0.5 | 100 | - | |
| LEV | ≥16 | 37.8 | p < 0.01 (−) | |
| MER | ≤0.06 | 100 | - | |
| PTZ | 64 | 72.4 | p < 0.01 (−) | |
| TIG | 0.5 | 98.9 | N.S. | |
| H. influenzae, BL-Pos (n = 269 [32/237]) | AMC | 2 | 98.1 | N.S. |
| AMP | ≥64 | 0.4 | N.S. | |
| CRO | ≤0.06 | 97.4 | N.S. | |
| IMP | 1 | 100 | - | |
| LEV | 0.015 | 100 | - | |
| MER | 0.12 | 100 | - | |
| MIN | 1 | 92.6 | N.S. | |
| K. pneumoniae, ESBL (n = 274 [19/255]) | AMK | 16 | 85.0 | N.S. |
| AMC | 32 | 16.1 | N.S. | |
| CFP | ≥64 | 7.3 | N.S. | |
| CRO | ≥128 | 1.8 | N.S. | |
| IMP | 0.5 | 100 | N.S. | |
| LEV | ≥16 | 29.6 | N.S. | |
| MER | 0.12 | 98.4 | - | |
| PTZ | ≥256 | 39.4 | N.S. | |
| TIG | 2 | 78.1 | N.S. |
aA negative (−) change in significance indicates an increase in susceptibility; N.S., not significant. A cut-off of p < 0.1 was used for statistical significance testing.
Values given in square parentheses refer to the number of isolates tested against imipenem and meropenem, respectively (and, where different, ampicillin [b]).
Only seven vancomycin-resistant E. faecalis were collected during this study; data not presented.