title: Prevalence and mechanisms of decreased susceptibility to carbapenems in Klebsiella pneumoniae isolates.
abstract: 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 microg/mL), we performed polymerase chain reaction amplification of a variety of beta-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 microg/mL and meropenem MICs of 4, 8, and 4, respectively. Isolate BD6 produced bla(TEM-1), bla(SHV-12), and bla(OXA-17); isolate BD8 produced bla(GES-3), bla(SHV-12), and bla(OXA-17); and isolate KN16 produced bla(TEM-11), bla(SHV-12), and bla(DHA-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 bla(GES-3), bla(TEM-11), bla(SHV-12), bla(OXA-17), and/or bla(DHA-1) are produced in combination with porin loss. In addition, to our knowledge, this is the 1st report of bla(OXA-17) in Enterobacteriaceae.
authors.affiliation: Department of Clinical Pathology, College of Medicine, The Catholic University of Korea, St. Vincent's Hospital, Suwon 442-723, South Korea.
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Yeon-Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Jin-Kyung
authors.initials: JK
authors.lastname: Yu
authors.forename: Han Sik
authors.initials: HS
authors.lastname: Kim
authors.forename: Yong Sung
authors.initials: YS
authors.lastname: Park
authors.forename: Jong-Bok
authors.initials: JB
authors.lastname: Yoon
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Yoo
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007525:Isoelectric Focusing; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000302:isolation & purification; D007723:Korea / Q000453:epidemiology; D013058:Mass Spectrometry; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D018272:Porins / Q000378:metabolism; D015995:Prevalence; D017422:Sequence Analysis, DNA; D013845:Thienamycins / Q000494:pharmacology*; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D018272:Porins; D013845:Thienamycins; D015378:Imipenem; D001618:beta-Lactamases; D000077731:Meropenem