In this study, we examined the prevalence of and mechanisms of decreased susceptibility to either imipenem or meropenem in Klebsiella pneumoniae isolates. A total of 230 clinical isolates of K. pneumoniae were collected from 13 clinical laboratories from a nationwide distribution. The MICs of imipenem and meropenem were determined by the agar dilution method. To characterize the isolates with decreased susceptibility to carbapenems (MICs of >2 μg/mL), we performed polymerase chain reaction amplification of a variety of β-lactamase genes, isoelectric focusing, and outer membrane profile analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. Three isolates (BD6, BD8, and KN16) exhibited decreased susceptibility to carbapenems with imipenem MICs of 1, 4, and 8 μg/mL and meropenem MICs of 4, 8, and 4, respectively. Isolate BD6 produced blaTEM-1, blaSHV-12, and blaOXA-17; isolate BD8 produced blaGES-3, blaSHV-12, and blaOXA-17; and isolate KN16 produced blaTEM-11, blaSHV-12, and blaDHA-1. In all the 3 isolates, OmpK35 porin was not expressed, and in 1 isolate (KN16), OmpK36 was not expressed either. The prevalence of decreased susceptibility to carbapenems was low (1.3%), and none of them showed overt resistance to carbapenems. Decreased susceptibility to carbapenems can occur in K. pneumoniae when blaGES-3, blaTEM-11, blaSHV-12, blaOXA-17, and/or blaDHA-1 are produced in combination with porin loss. In addition, to our knowledge, this is the 1st report of blaOXA-17 in Enterobacteriaceae.
|Number of pages||7|
|Journal||Diagnostic Microbiology and Infectious Disease|
|Publication status||Published - 2007 Jan 1|
All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases