Table 3.

MIC and susceptibility data for K. pneumoniae

Inoculum (CFU/ml) (n) and antibioticMICc (μg/ml)% Susceptiblea,b
Range50%90%
105(18)
 Meropenem≤0.015–0.120.030.06100
 Cefoteten0.06–20.251100
 Cefotaxime0.5–6443267
 Ceftazidime1–>1,0242561,02411
 Ceftriaxone1–12846456
 Cefepime0.5–1641689
 Aztreonam0.5–>1,0246451222
 Pip-Tazo2–1,02481,02467
107(18)
 Meropenem0.03–40.1254100 (6/18)
 Cefoteten0.06–3221690 (6/18)
 Cefotaxime8–>1,024256>1,0245 (18/18)
 Ceftazidime8–>1,024>1,024>1,0245 (6/8)
 Ceftriaxone128–>1,024>1,024>1,0240 (18/18)
 Cefepime>128>128>1280 (18/18)
 Aztreonam4–>1,024>1,024>1,02411 (8/12)
 Pip-Tazo4–>1,0241,024>1,02422 (8/14)
  • a Susceptibility based on the percentage of strains inhibited at the NCCLS susceptible breakpoint concentration of each agent. (The breakpoints are only validated for the tests with the 105 CFU/ml inoculum.)

  • b For the inoculum of 107 CFU/ml, in addition to percent susceptibility, the following is shown parenthetically: number of strains showing inoculum effect/number of strains evaluable. (Not all tests were evaluable. For some MICs out of the test range it was impossible to determine if there was an eightfold increase in MIC.)

  • c 50 and 90%, MICs at which 50 and 90% of isolates are inhibited, respectively.