Table 2.
Prevalences of clinical isolates showing AmpC or efflux pump overexpression
| Resistance gene(s) | No. (%) of isolates with: |
||
|---|---|---|---|
| Overexpressiona | Borderline expression | No overexpression | |
| Any gene | 74 (39.0) | 21 (11.1) | 95 (49.9) |
| ampC | 46 (24.2) | 6 (3.2) | 138 (72.6) |
| mexY | 25 (13.2) | 10 (5.3) | 155 (81.5) |
| mexB | 24 (12.6) | 8 (4.2) | 158 (83.2) |
| mexF | 8 (4.2) | 10 (5.3) | 172 (90.5) |
| mexD | 4 (2.1) | 3 (1.6) | 183 (96.3) |
| Most frequently found combinations | |||
| mexB + mexY | 10 (5.3) | 3 (1.6) | 177 (93.2) |
| ampC + mexY | 10 (5.3) | 2 (1.1) | 178 (93.7) |
| ampC + mexB | 8 (4.2) | 2 (1.1) | 180 (94.7) |
| ampC + mexB + mexY | 3 (1.6) | 2 (1.1) | 185 (97.4) |
a
Mean values (and ranges) of overexpression (fold increase compared to PAO1) were 419.7 (14.5 to 3,586.1) for ampC, 20.9 (10.2 to 37.4) for mexY, 5.6 (3.1 to 13.3) for mexB, 20.5 (14.2 to 33.2) for mexF, and 20.7 (13.3 to 38.4) for mexD.