Table 1. Distributions of MIC for 477 GBS isolates from pregnant women.
| Antibiotics | MIC (μg/ml) | Number of non-susceptible isolates (%) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.01 | 0.03 | 0.06 | 0.12 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | >128 | ||
| Penicillin G | 7 | 264 | 204 | 2 | 0 (0) | |||||||||||
| Ampicillin | 1 | 18 | 160 | 276 | 22 | 0 (0) | ||||||||||
| Oxacillin | 2 | 7 | 248 | 218 | 2 | * | ||||||||||
| Cefazolin | 25 | 248 | 182 | 22 | * | |||||||||||
| Ceftibuten | 6 | 110 | 322 | 34 | 2 | 3 | * | |||||||||
| Ceftizoxime | 14 | 282 | 172 | 3 | 2 | 2 | 2 | * | ||||||||
| Meropenem | 8 | 328 | 132 | 9 | 0 (0) | |||||||||||
| Erythromycin | 20 | 192 | 82 | 30 | 33 | 28 | 20 | 10 | 5 | 1 | 2 | 3 | 51 | 153 (32.1) | ||
| Clindamycin | 7 | 145 | 244 | 16 | 5 | 3 | 1 | 6 | 1 | 0 | 3 | 3 | 4 | 39 | 60 (12.6) | |
*The Clinical and Laboratory Standards Institute (CLSI) does not provide breakpoints of oxacillin, cefazolin, ceftibuten, and ceftizoxime.
The breakpoints for categorisation as “Susceptible” set by the CLSI are ≤0.12 μg/ml (penicillin G), ≤0.25 μg/ml (ampicillin), ≤0.5 μg/ml (meropenem), ≤0.25 μg/ml (erythromycin), and ≤0.25 μg/ml (clindamycin).
Abbreviation: GBS, group B Streptococcus; MIC, minimum inhibitory concentration.