title: In Vitro Activity of Imipenem and Colistin against a Carbapenem-Resistant Klebsiella pneumoniae Isolate Coproducing SHV-31, CMY-2, and DHA-1.
abstract: We investigated the synergism of colistin and imipenem against a multidrug-resistant K. pneumoniae isolate which was recovered from a severe hip infection. PCR and DNA sequencing were used to characterize the outer membrane porin genes and the resistance genes mediating the common β-lactamases and carbapenemases. Synergism was evaluated by time-kill studies. The bla SHV-31, bla CMY-2, and bla DHA-1 were detected. Outer membrane porin genes analysis revealed loss of ompK36 and frame-shift mutation of ompK35. The common carbapenemase genes were not found. Time-kill studies demonstrated that a combination of 1x MIC of colistin (2 mg/L) and 1x MIC of imipenem (8 mg/L) was synergistic and bactericidal but with inoculum effect. Bactericidal activity without inoculum effect was observed by concentration of 2x MIC of colistin alone or plus 2x MIC of imipenem. In conclusion, colistin plus imipenem could be an alternative option to treat carbapenem-resistant K. pneumoniae infections.
authors.affiliation: Department of Internal Medicine, Chi Mei Medical Center, Tainan City 71004, Taiwan ; Department of Health and Nutrition, Chia Nan University of Pharmacy and Science, Tainan City 71710, Taiwan.
authors.forename: Hung-Jen
authors.initials: HJ
authors.lastname: Tang
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, Chi Mei Medical Center-Liu Ying, Tainan City 73657, Taiwan.
authors.forename: Yee-Huang
authors.initials: YH
authors.lastname: Ku
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan City 71004, Taiwan.
authors.forename: Mei-Feng
authors.identifier: 0000-0002-5101-2760
authors.initials: MF
authors.lastname: Lee
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, Chi Mei Medical Center-Liu Ying, Tainan City 73657, Taiwan ; Department of Medical Research, Chi Mei Medical Center, Tainan City 71004, Taiwan.
authors.forename: Yin-Ching
authors.initials: YC
authors.lastname: Chuang
authors.affiliation: Department of Intensive Care Medicine, Chi Mei Medical Center, No. 901 Zhonghua Road, Yongkang District, Tainan City 71004, Taiwan ; Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei City 11042, Taiwan.
authors.forename: Wen-Liang
authors.identifier: 0000-0002-7345-800X
authors.initials: WL
authors.lastname: Yu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification*; D015780:Carbapenems / Q000008:administration & dosage; D003091:Colistin / Q000008:administration & dosage; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004357:Drug Synergism; D006615:Hip / Q000382:microbiology / Q000473:pathology; D006801:Humans; D015378:Imipenem / Q000008:administration & dosage; D007710:Klebsiella Infections / Q000235:genetics / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000472:pathogenicity; D018272:Porins / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D015780:Carbapenems; D018272:Porins; D015378:Imipenem; C103022:beta-lactamase CMY-2; D001618:beta-Lactamases; C000601045:beta-lactamase DHA-1, Klebsiella pneumoniae; C519492:beta-lactamase SHV-31, Klebsiella pneumoniae; D003091:Colistin