title: Molecular epidemiology of blaOXA-23-producing carbapenem-resistant Acinetobacter baumannii in a single institution over a 65-month period in north China.
abstract: Carbapenem-resistant Acinetobacter baumannii poses a significant threat to hospitalized patients, as few therapeutic options remain. Thus, we investigated the molecular epidemiology and mechanism of resistance of carbapenem-resistant A.baumannii isolates in Beijing, China.
  
  
  
  Carbapenem-resistant A.baumannii isolates (n = 101) obtained between June 2009 and November 2014 were used. Multilocus sequence typing (MLST) and PCR assays for class C and D β-lactamase were performed on all isolates. S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization were performed to identify the resistance gene location.
  
  
  
  All 101 A.baumannii isolates were highly resistant to frequently used antimicrobials, and were considered multidrug resistant. A total of 12 sequence types (STs) were identified, including 10 reported STs and 2 novel STs. Eighty-seven isolates were classified to clonal complex 92 (CC92), among which ST191 and ST195 were the most common STs. The blaOXA-23gene was positive in most (n = 95) of the A.baumannii isolates. Using S1-nuclease digestion PFGE and Southern blot hybridization, 3 patterns of plasmids carrying blaOXA-23were confirmed. ST191 and ST195 (both harboring blaOXA-23) caused outbreaks during the study period, and this is the first report of outbreaks caused by ST191 and ST195 in north China.
  
  
  
  blaOXA-23-producing A.baumannii ST191 and ST 195 isolates can disseminate in a hospital and are potential nosocomial outbreak strains. Surveillance of imipenem-resistant A.baumannii and antimicrobial stewardship should be strengthened.
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China.
authors.forename: Nian-Zhi
authors.initials: NZ
authors.lastname: Ning
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Liu
authors.affiliation: The Center of Clinical Diagnosis Laboratory, Beijing 302 Hospital, Beijing, 100039, China.
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Bao
authors.affiliation: The Center of Clinical Diagnosis Laboratory, Beijing 302 Hospital, Beijing, 100039, China.
authors.forename: Su-Ming
authors.initials: SM
authors.lastname: Chen
authors.affiliation: The Center of Clinical Diagnosis Laboratory, Beijing 302 Hospital, Beijing, 100039, China.
authors.forename: En-Bo
authors.initials: EB
authors.lastname: Cui
authors.affiliation: The Center of Clinical Diagnosis Laboratory, Beijing 302 Hospital, Beijing, 100039, China.
authors.forename: Ju-Ling
authors.initials: JL
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China.
authors.forename: Fang-Hong
authors.initials: FH
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China. litaobmi@126.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: The Center of Clinical Diagnosis Laboratory, Beijing 302 Hospital, Beijing, 100039, China. qf302@163.com.
authors.forename: Fen
authors.initials: F
authors.lastname: Qu
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, No.20 Dongda Street, Fengtai District, 100071, Beijing, China. geno0109@vip.sina.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology*; D040981:Acinetobacter baumannii / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015373:Bacterial Typing Techniques; D015780:Carbapenems / Q000627:therapeutic use*; D002681:China / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005500:Follow-Up Studies; D006801:Humans; D015378:Imipenem / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D015378:Imipenem; C466679:beta-lactamase OXA-23; D001618:beta-Lactamases
keywords: Acinetobacter baumannii; CC92; Carbapenem resistant; Outbreak; bla OXA-23