Prevalence and mechanisms of decreased susceptibility to carbapenems in Klebsiella pneumoniae isolates.
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.
Kim
Soo-Young
SY
Department of Clinical Pathology, College of Medicine, The Catholic University of Korea, St. Vincent's Hospital, Suwon 442-723, South Korea.
Park
Yeon-Joon
YJ
Yu
Jin-Kyung
JK
Kim
Han Sik
HS
Park
Yong Sung
YS
Yoon
Jong-Bok
JB
Yoo
Jin-Young
JY
Lee
Kyungwon
K
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
D000900:Anti-Bacterial Agents; D018272:Porins; D013845:Thienamycins; D015378:Imipenem; D001618:beta-Lactamases; D000077731:Meropenem