TABLE 3.
Susceptibility to azithromycin and clarithromycin of isolates of H. influenzae, 1996–1997
| β-Lactamase status by U.S. region | No. of isolates | No. (%)a of azithromycin isolates susceptibleb | No. (%)a of clarithromycin isolates susceptibleb |
|---|---|---|---|
| East | |||
| Negative | 532 | 528 (99) | 416 (78) |
| Positive | 297 | 294 (99) | 209 (70) |
| Both | 829 | 822 (99) | 625 (75) |
| Midwest | |||
| Negative | 523 | 518 (99) | 421 (81) |
| Positive | 233 | 228 (98) | 184 (79) |
| Both | 756 | 746 (99) | 605 (80) |
| West | |||
| Negative | 287 | 284 (99) | 225 (78) |
| Positive | 119 | 119 (100) | 88 (74) |
| Both | 406 | 403 (99) | 313 (77) |
| All regions | |||
| Negative | 1,342 | 1,330 (99) | 1,062 (79) |
| Positive | 649 | 641 (99) | 481 (74) |
| Both | 1,991 | 1,971 (99) | 1,543 (78) |
a
Rounded to the nearest whole number.
b
Based on NCCLS (2) susceptibility breakpoints for azithromycin and clarithromycin (≤4 and ≤8 μg/ml, respectively).