title: Differential susceptibility to carbapenems due to the AdeABC efflux pump among nosocomial outbreak isolates of Acinetobacter baumannii in a Chinese hospital.
abstract: A nosocomial outbreak of carbapenem-resistant Acinetobacter baumannii occurred from February to November 2004 in the surgical intensive care unit (SICU) and the pediatric intensive care unit (PICU) of our hospital. Two separate clones prevailed, the antimicrobial susceptibility profiles of which were different. The PICU isolates produced OXA-23 oxacillinase, whereas no carbapenemases were detected from SICU isolates. No obvious outer membrane protein change was seen. Efflux pump phenotype was detected from SICU isolates. Efflux pump-encoding gene adeB was positive in these isolates and negative in PICU isolates. Through further study, we found that AdeABC efflux system gene contents were common in the SICU isolates. Then we compared the expression level of adeB in resistant and susceptible isolates using quantitative real-time polymerase chain reaction and found that increased expression of AdeABC efflux pump may play an important role in reduced meropenem susceptibility among A. baumannii in the SICU of our hospital.
authors.affiliation: Department of Clinical Laboratory, Peking University First Hospital, Beijing 100034, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Liying
authors.initials: L
authors.lastname: Sun
authors.forename: Guobing
authors.initials: G
authors.lastname: Xu
authors.forename: Tiean
authors.initials: T
authors.lastname: Xia
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015780:Carbapenems / Q000494:pharmacology*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002648:Child; D002681:China / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*; D004196:Disease Outbreaks; D005798:Genes, Bacterial; D006801:Humans; D007362:Intensive Care Units; D007525:Isoelectric Focusing; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics
chemical_list: C492436:AdeA protein, Acinetobacter baumannii; C445684:AdeB protein, Acinetobacter baumannii; C492437:AdeC protein, Acinetobacter baumannii; D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D015780:Carbapenems; D026901:Membrane Transport Proteins; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D001618:beta-Lactamases; C063912:carbapenemase