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. 2003 Jan;47(1):148–153. doi: 10.1128/AAC.47.1.148-153.2003

TABLE 2.

Comparison of in vitro susceptibility rates of blood isolates of the B. fragilis group

Antimicrobial agent No. of isolates tested MIC (μg/ml)
All isolates (%S)a Cfx-I&Rb
Clin-I&Rc
Range Mode MIC50 MIC90 %S %SΔd %S %SΔ
Penicillin G 160 0.06-128 8 8 128 0 0 0 0 0
Piperacillin 384 0.12-256 2 8 128 77 46 −31 60 −17
Ticarcillin 137 0.12-256 16 32 128 63 21 −42 39 −24
Piperacillin-tazobactam 142 0.06-64 2 1 8 99.3 96 −3.3 96.1 −3.2
Ticarcillin-clavulanate 191 0.25-256 1 0.5 8 96 83 −13 86 −10
Ampicillin-sulbactam 382 0.03-128 1 1 8 93 81 −12 80 −13
Cefotaxime 384 0.06-256 4 8 64 62 32 −30 34 −28
Ceftriaxone 138 1-128 2 32 128 49 7 −42 7 −42
Cefoxitin 515 0.12-128 8 8 32 84 0 73 −11
Cefotetan 473 0.06-256 8 8 64 64 8 −56 26 −38
Cefmetazole 84 0.25-128 8 16 64 61 0 −61 35 −26
Ceftizoxime 358 0.06-256 4 4 64 78 67 −11 65 −13
Imipenem 378 0.015-32 0.03 0.12 1 99.5 97 −2.5 98 −1.5
Meropenem 127 0.015-32 0.12 0.5 0.5 98 94 −4 94 −4
Ertapenem 92 0.06-32 0.25 0.25 2 94 64 −30 86 −8
Trovafloxacin 156 0.03-16 0.25 0.25 2 96 86 −10 88 −8
Clindamycin 542 0.015-64 0.25 0.5 16 78 63 −15 0
Metronidazole 542 0.06-8 1 1 2 100 100 0 100 0
a

The following MIC values (μg/ml) were used as susceptibility breakpoints as recommended by the NCCLS (14): penicillin G, ≤0.5; piperacillin, ≤32; ticarcillin, ≤32; piperacillin-tazobactam, ≤32; ticarcillin-clavulanate, ≤32; ampicillin-sulbactam, ≤8; cefotaxime, ≤16; ceftriaxone, ≤16; cefoxitin, ≤16; cefotetan, ≤16; cefmetazole, ≤16; ceftizoxime, ≤16; imipenem, ≤4; meropenem, ≤4; trovafloxacin, ≤2; clindamycin, ≤2; and metronidazole, ≤8. Ertapenem susceptibility was ≤4 μg/ml, as recommended by the manufacturer. Test isolates with higher than stated susceptible MICs were considered “not susceptible” and were comprised of isolates with MICs interpreted as intermediate or fully resistant.

b

Contains isolates with cefoxitin (Cfx) MICs of ≥32 μg/ml.

c

Contains isolates with clindamycin (Clin) MICs of ≥4 μg/ml.

d

Indicates the decrease in the percentage of isolates susceptible to isolates “not-susceptible” to cefoxitin or clindamycin.