title: Loss of the 29-kilodalton outer membrane protein in the presence of OXA-51-like enzymes in Acinetobacter baumannii is associated with decreased imipenem susceptibility.
abstract: Carbapenem resistance in Acinetobacter baumannii is increasing these days. We investigated the roles of outer membrane proteins and efflux pumps in carbapenem resistance of A. baumannii which showed no carbapenemase activity in modified Hodge test. Among 58 carbapenem-resistant isolates collected from the Korea University Medical Center between January 2002 and March 2006, 17 isolates showed negative results in modified Hodge test. In outer membrane protein analysis, loss of the 29-kDa protein band was related with higher imipenem minimum inhibitory concentrations especially in the presence of OXA-51-like enzymes. Efflux pump-mediated carbapenem resistance was found in one out of the 17 isolates (5.9%). All of the 58 carbapenem-resistant strains and 5 of the 10 carbapenem-susceptible strains had OXA-51-like carbapenemase genes, suggesting that OXA-51-like enzymes may be naturally existing in A. baumannii and have very weak carbapenem hydrolyzing activity.
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jeong
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Cheong
authors.forename: Woo Joo
authors.initials: WJ
authors.lastname: Kim
authors.forename: Min Ja
authors.initials: MJ
authors.lastname: Kim
authors.forename: Ki-Joon
authors.initials: KJ
authors.lastname: Song
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Song
authors.forename: H Stanley
authors.initials: HS
authors.lastname: Kim
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Roh
mesh_terms: D000046:Academic Medical Centers; D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007723:Korea; D008826:Microbial Sensitivity Tests; D019105:Random Amplified Polymorphic DNA Technique; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: C471341:29-kDa outer membrane protein, Acinetobacter baumannii; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015378:Imipenem; D001618:beta-Lactamases; C063912:carbapenemase