Table 1.
In vitro activity of 10 antimicrobial agents against 363 isolates of the Bacteroides fragilis group
| Organism (no. of isolates) and antimicrobial agent(s) | MIC (μg/ml) |
% of isolates with the indicated susceptibility: |
||||
|---|---|---|---|---|---|---|
| Range | 50% | 90% | Susceptible | Intermediate | Resistant | |
| Bacteroides fragilis (198) | ||||||
| Ampicillin-sulbactam | 0.125–128 | 1 | 8 | 97.0 | 1.5 | 1.5 |
| Piperacillin-tazobactam | ≤0.03–>512 | 0.25 | 2 | 98.5 | 0.0 | 1.5 |
| Cefoxitin | 1–256 | 16 | 32 | 82.8 | 11.1 | 6.1 |
| Ertapenem (126) | 0.06–>64 | 0.25 | 4 | 96.0 | 1.6 | 2.4 |
| Imipenem | ≤0.015–>64 | 0.125 | 0.5 | 98.5 | 0.0 | 1.5 |
| Doripenem (159) | 0.03–>64 | 0.25 | 1 | 97.5 | 0.6 | 1.9 |
| Clindamycin | ≤0.125–>256 | 1 | >256 | 74.7 | 2.5 | 22.7 |
| Metronidazole | ≤0.06–4 | 0.5 | 1 | 100.0 | 0.0 | 0.0 |
| Moxifloxacin | 0.06–64 | 0.5 | 2 | 89.9 | 2.0 | 8.1 |
| Tigecycline | ≤0.03–4 | 0.125 | 1 | 100 | 0.0 | 0.0 |
| Bacteroides thetaiotaomicron/ovatus (69) | ||||||
| Ampicillin-sulbactam | 0.5–32 | 0.5 | 1 | 87.0 | 8.7 | 4.3 |
| Piperacillin-tazobactam | ≤0.03–64 | ≤0.03 | 4 | 98.6 | 1.4 | 0.0 |
| Cefoxitin | 4–128 | 4 | 32 | 49.3 | 27.5 | 23.2 |
| Ertapenem (49) | 0.125–>64 | 0.12 | 1 | 89.8 | 4.1 | 4.1 |
| Imipenem | ≤0.015–16 | ≤0.015 | 0.125 | 98.6 | 0.0 | 1.4 |
| Doripenem (58) | 0.125–64 | 0.125 | 0.25 | 96.6 | 0.0 | 3.4 |
| Clindamycin | ≤0.125–>256 | ≤0.125 | 4 | 42.0 | 18.8 | 39.1 |
| Metronidazole | ≤0.06–2 | ≤0.06 | 0.5 | 100.0 | 0.0 | 0.0 |
| Moxifloxacin | 0.125–64 | 0.125 | 1 | 89.9 | 2.9 | 7.2 |
| Tigecycline | ≤0.03–2 | ≤0.03 | 0.125 | 100.0 | 0.0 | 0.0 |
| Bacteroides caccae (30) | ||||||
| Ampicillin-sulbactam | 0.5–16 | 1 | 4 | 90 | 10 | 0 |
| Piperacillin-tazobactam | ≤0.03–8 | 0.25 | 4 | 100 | 0 | 0 |
| Cefoxitin | 4–128 | 16 | 64 | 63.3 | 16.7 | 20 |
| Ertapenem (19) | 0.125–8 | 0.5 | 4 | 94.7 | 5.3 | 0 |
| Imipenem | ≤0.015–2 | 0.125 | 0.5 | 100 | 0 | 0 |
| Doripenem (25) | 0.125–8 | 0.25 | 1 | 96 | 4 | 0 |
| Clindamycin | ≤0.125–>256 | 1 | >256 | 63.3 | 10 | 26.7 |
| Metronidazole | ≤0.06–4 | 0.5 | 1 | 100 | 0 | 0 |
| Moxifloxacin | 0.125–16 | 0.5 | 4 | 86.7 | 6.7 | 6.7 |
| Tigecycline | ≤0.03–4 | 0.5 | 1 | 100.0 | 0 | 0.0 |
| Bacteroides vulgatus (27) | ||||||
| Ampicillin-sulbactam | 0.125–128 | 4 | 16 | 74.1 | 18.5 | 7.4 |
| Piperacillin-tazobactam | 0.25–512 | 2 | 8 | 96.3 | 0.0 | 3.7 |
| Cefoxitin | 0.5–128 | 8 | 32 | 81.5 | 7.4 | 11.1 |
| Ertapenem (24) | 0.125–2 | 0.5 | 1 | 100.0 | 0.0 | 0.0 |
| Imipenem | ≤0.015–4 | 0.25 | 1 | 100.0 | 0.0 | 0.0 |
| Doripenem | 0.06–1 | 0.25 | 0.5 | 100.0 | 0.0 | 0.0 |
| Clindamycin | ≤0.125–>256 | 0.5 | >256 | 66.7 | 3.7 | 29.6 |
| Metronidazole | 0.25–4 | 0.5 | 1 | 100.0 | 0.0 | 0.0 |
| Moxifloxacin | 0.06–128 | 1 | 8 | 81.5 | 3.7 | 14.8 |
| Tigecycline | ≤0.03–2 | 0.06 | 0.5 | 100.0 | 0.0 | 0.0 |
| Uncommon B. fragilis group species (39)a | ||||||
| Ampicillin-sulbactam | ≤0.125–32 | 2 | 16 | 87.2 | 10.3 | 2.6 |
| Piperacillin-tazobactam | ≤0.03–64 | 1 | 8 | 97.4 | 2.6 | 0.0 |
| Cefoxitin | 4–128 | 16 | 64 | 61.5 | 20.5 | 17.9 |
| Ertapenem (34) | 0.06–16 | 0.5 | 2 | 97.1 | 0.0 | 2.9 |
| Imipenem | 0.03–4 | 0.25 | 0.5 | 100.0 | 0.0 | 0.0 |
| Doripenem (37) | 0.125–4 | 0.25 | 1 | 100.0 | 0.0 | 0.0 |
| Clindamycin | ≤0.125–>256 | 2 | >256 | 51.3 | 7.7 | 41.0 |
| Metronidazole | 0.06–4 | 0.5 | 2 | 100.0 | 0.0 | 0.0 |
| Moxifloxacin | ≤0.03–64 | 1 | 16 | 79.5 | 5.1 | 15.4 |
| Tigecycline | ≤0.03–4 | 0.125 | 1 | 100.0 | 0.0 | 0.0 |
a
The 39 uncommon isolates of the B. fragilis group species were found to belong to the following species: Parabacteroides (Bacteroides) distasonis, 7 isolates; Bacteroides uniformis, 7 isolates; Bacteroides stercoris, 7 isolates; Bacteroides merdae, 2 isolates; and Bacteroides spp., 16 isolates.