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Table 2 Antibiotic susceptibility profiles of 43 GBS isolates from pregnant women

From: Analysis of virulence factors and antibiotic resistance genes in group B streptococcus from clinical samples

Antibiotic   MIC (μg/ml) c
  Resistant no. (%) Intermediate no. (%) Susceptible no. (%) MIC50 MIC90 Range
Disk diffusiona
 Penicillin G (10 units) 30/43 (69.8%) 0 (0%) 13/43 (30.2%) d
 Ampicillin (10 μg) 25/43 (58.1%) 0 (0%) 18/43 (41.9%)
 Tetracycline (30 μg) 42/43 (97.6%) 0 (0%) 1 (2.3%)
 Clindamycin (2 μg) 24/43 (55.8%) 11/43 (25.6%) 8/43 (18.6%)
 Erythromycin (15 μg) 13/43 (30.2%) 16/43 (37.2%) 14/43 (32.6%)
 Vancomycin (30 μg) 13/43 (30.2%) 0 (0%) 30/43 (69.8%)
 Cefazolin (30 μg) 31/43 (72.1%) 0 (0%) 12/43 (27.9%)
 Chloramphenicol (30 μg) 15/43 (34.9%) 16/43 (37.2%) 12/43 (27.9%)
 Ceftriaxone (30 μg) 20/43 (46.5%) 0 (0%) 23/43 (53.5%)
E-testb
 Ampicillin 20/43 (46.5%) 0 (0%) 23/43 (53.5%) 0.25 0.75 0.016 to 4
 Vancomycin 16/43 (37.2%) 0 (0%) 30/43 (63.7%) 1 4 0.25 to 8
 Chloramphenicol 0/43 (0%) 2/43 (4.7%) 12/43 (95.3%) 1.5 4 0 to 12
  1. a Testing was performed by disk diffusion
  2. b Testing was performed with E-test
  3. cMIC50 and MIC90, MICs at which 50 and 90% of isolates were inhibited, respectively
  4. d —, not available
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