Table 1.
Prevalence of different resistance mechanisms among isolates in the United States.
| Drug class | Mechanism | Number of isolates | Percentage of isolates |
|---|---|---|---|
| Fluoroquinolones | GyrA (S84L) | 177 | 29.9% |
| GyrA (S84A) | 1 | 0.2% | |
| GyrA (S84W) | 1 | 0.2% | |
| GyrA (E88G) | 1 | 0.2% | |
| GyrA (E88K) | 1 | 0.2% | |
| GyrA (S84L, S85A) | 1 | 0.2% | |
| GrlA (S80I) | 213 | 36.0% | |
| GrlA (S80R) | 12 | 2.0% | |
| GrlA (D84N) | 8 | 1.4% | |
| GrlA (D84G) | 6 | 1.0% | |
| GrlA (D84Y) | 3 | 0.5% | |
| GrlA (S80I, D84H) | 1 | 0.2% | |
| Tetracyclines | tet(M) | 267 | 45.1 % |
| tet(K) | 11 | 1.9% | |
| Folate synthesis inhibitors | dfrG | 202 | 34.1% |
| dfrC | 3 | 0.5% | |
| Beta-lactams | mecA | 191 | 32.3 % |
| blaZ | 443 | 74.8 % | |
| Phenicols | catA | 52 | 8.8% |
| Macrolides | erm(A) | 1 | 0.2% |
| erm(B) | 205 | 34.6 % | |
| erm(C) | 2 | 0.3% | |
| Ansamycins | RpoB (S486L) | 1 | 0.2% |
| RpoB (H481Y) | 1 | 0.2% | |
| RpoB (Ala after A473) | 1 | 0.2% | |
| Aminoglycosides | aac(6’)-Ie-aph (2”)-Ia | 145 | 24.5% |
| ant(6)-Ia/aph (3’)-IIIa | 211 | 35.6 % | |
| ant(9)-Ia | 1 | 0.2% | |
| Mupirocin | mupA | 3 | 0.5% |
| Lincosamides | lnu(A) | 10 | 1.7% |
| lnu(G) | 2 | 0.3% | |
| Streptothricin | sat4 | 211 | 35.6 % |