Table 2.
The results of β‐lactamase activity and antibiotic susceptibility pattern of H influenzae isolates
| β‐lactamase/Antimicrobials | Total (n = 190) | Study sites | |||
|---|---|---|---|---|---|
| Beijing (n = 99) |
Youyang (n = 91) |
χ 2 | P | ||
| β‐lactamase‐positive [n(%)] | 44 (23%) | 22 (22.2%) | 22 (24.1%) | 0.102 | .750 |
| TEM [n (%)] | 42 (95%) | 22 (100%) | 20 (90.9%) | ||
| ROB [n (%)] | 0 (0%) | 0 (0%) | 0 (0%) | ||
| Ampicillin | 3.845 | .050 | |||
| Susceptible [n (%)] | 112 (58.9%) | 65 (65.7%) | 47 (51.6%) | ||
| Intermediate [n (%)] | 25 (13.2%) | 10 (10.1%) | 15 (16.5%) | ||
| Resistant [n (%)] | 53 (27.9%) | 24 (24.2%) | 29 (31.9%) | ||
| MIC50 (mg/L) | 1 | 0.75 | 1 | ||
| MIC90 (mg/L) | ≥256 | 12 | ≥256 | ||
| MIC range (mg/L) | 0.094 to ≥256 | 0.094 to ≥256 | 0.125 to ≥256 | ||
| Amoxicillin‐clavulanic acid | 1.640 | .200 | |||
| Susceptible [n (%)] | 177 (93.2%) | 90 (90.9%) | 87 (95.6%) | ||
| Resistant [n (%)] | 13 (6.8%) | 9 (9.1%) | 4 (4.4%) | ||
| MIC50 (mg/L) | 1 | 0.5 | 1 | ||
| MIC90 (mg/L) | 3 | 4 | 3 | ||
| MIC range (mg/L) | 0.023 to ≥256 | 0.023 to ≥256 | 0.25 to ≥256 | ||
| Cefuroxime | 0.696 | .404 | |||
| Susceptible [n (%)] | 151 (79.5%) | 81 (81.8%) | 70 (76.9%) | ||
| Intermediate [n (%)] | 16 (8.4%) | 7 (7.1%) | 9 (9.9%) | ||
| Resistant [n (%)] | 23 (12.1%) | 11 (11.1%) | 12 (13.2%) | ||
| MIC50 (mg/L) | 1 | 1 | 1 | ||
| MIC90 (mg/L) | 16 | 16 | 24 | ||
| MIC range (mg/L) | 0.064 to ≥256 | 0.064 to ≥256 | 0.19 to ≥256 | ||
| Ceftriaxone | — | — | |||
| Susceptible [n (%)] | 190 (100%) | 99 (100%) | 91 (100%) | ||
| MIC50 (mg/L) | 0.016 | 0.016 | 0.016 | ||
| MIC90 (mg/L) | 0.19 | 0.19 | 0.19 | ||
| MIC range (mg/L) | 0.002‐5 | 0.002‐0.5 | 0.002‐0.25 | ||
| Levofloxacin | — | — | |||
| Susceptible [n (%)] | 190 (100%) | 99 (100%) | 91 (100%) | ||
| MIC50 (mg/L) | 0.016 | 0.016 | 0.016 | ||
| MIC90 (mg/L) | 0.25‐0.75 | 0.25 | 0.75 | ||
| MIC range (mg/L) | 0.004‐1 | 0.004‐0.5 | 0.008‐1 | ||
| Erythromycin | 13.970 | <.001 | |||
| Susceptible [n (%)] | 104 (54.7%) | 67 (67.7%) | 37 (40.7%) | ||
| Intermediate [n (%)] | — | — | — | ||
| Resistant [n (%)] | — | — | — | ||
| MIC50 (mg/L) | 4 | 4 | 6 | ||
| MIC90 (mg/L) | 256 | 64 | ≥256 | ||
| MIC range (mg/L) | 0.38 to ≥256 | 0.38 to ≥256 | 2 to ≥256 | ||
| Tetracycline | 2.885 | .089 | |||
| Susceptible [n (%)] | 179 (94.2%) | 96 (97%) | 83 (91.2%) | ||
| Intermediate [n (%)] | 4 (2.1%) | 2 (2%) | 2 (2.2%) | ||
| Resistant [n (%)] | 7 (3.7%) | 1 (1%) | 6 (6.6%) | ||
| MIC50 (mg/L) | 0.25 | 0.25 | 0.38 | ||
| MIC90 (mg/L) | 0.5 | 0.38 | 0.5 | ||
| MIC range (mg/L) | 0.047‐12 | 0.047‐12 | 0.19‐8 | ||
| Sulfamethoxazole‐trimethoprim | 4.322 | .038 | |||
| Susceptible [n (%)] | 73 (38.4%) | 45 (45.5%) | 28 (30.8%) | ||
| Intermediate [(%)] | 4.7% | 7.1% | 2.2% | ||
| Resistant [(%)] | 56.8% | 47.5% | 67% | ||
| MIC50 (mg/L) | ≥32 | 2 | ≥32 | ||
| MIC90 (mg/L) | ≥32 | ≥32 | ≥32 | ||
| MIC range (mg/L) | 0.008 to ≥32 | 0.008 to ≥32 | 0.047 to ≥32 | ||
| Chloramphenicol | 2.885 | .089 | |||
| Susceptible [n (%)] | 179 (94.2%) | 96 (96%) | 83 (91.2%) | ||
| Intermediate [n (%)] | 1 (0.5%) | 0 | 1 (1.1%) | ||
| Resistant [n (%)] | 10 (5.3%) | 4 (4%) | 6 (6.6%) | ||
| MIC50 (mg/L) | 0.5 | 0.38 | 0.5 | ||
| MIC90 (mg/L) | 0.75 | 0.5 | 1 | ||
| MIC range (mg/L) | 0.094 to ≥256 | 0.094‐8 | 0.25 to ≥256 | ||