title: Emergence in Taiwan of novel imipenem-resistant Acinetobacter baumannii ST455 causing bloodstream infection in critical patients.
abstract: BACKGROUND
  Acinetobacter baumannii is one of the most important nosocomial pathogens worldwide. This study aimed to use multilocus sequence typing (MLST) for the epidemiological surveillance of A. baumannii isolates in Taiwan and analyze the clinical presentations and patients' outcome.
  
  
  METHODS
  MLST according to both Bartual's PubMLST and Pasteur's MLST schemes was applied to characterize bloodstream imipenem-resistant A. baumannii (IRAB) infection in intensive care units in a medical center. A total of 39 clinical IRAB bloodstream isolates in 2010 were enrolled. We also collected 13 imipenem-susceptible A. baumannii (ISAB) bloodstream isolates and 30 clinical sputum isolates (24 IRAB and 6 ISAB) for comparison. Clinical presentations and outcome of the patients were analyzed.
  
  
  RESULTS
  We found that infection by ST455(B)/ST2(P) and inappropriate initial therapy were statistically significant risk factors for mortality. More than one-third of the IRAB isolates belonged to ST455(B)/ST2(P). Most ST455(B)/ST2(P) (80%) carried ISAba1-blaOXA-23, including 10 (66.7%) with Tn2006 (ISAba1-blaOXA-23-ISAba1) in an AbaR4-type resistance island. ST455(B)/ST2(P) appears to evolve from ST208(B)/ST2(P) of clonal complex (CC) 92(B)/CC2(P). In this hospital-based study, A. baumannii ST455 accounted for 38.5% of IRAB bacteremia, with a high mortality of 86.7%. Approximately 85% of ST455(B)/ST2(P)bacteremia had a primary source of ventilation-associated pneumonia.
  
  
  CONCLUSIONS
  We report the emergence in Taiwan of IRAB ST455(B)/ST2(P), which is the current predominant clone of IRAB in our hospital and has been causing bacteremia with high mortality in critical patients.
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan; Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan; Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Hao-Yuan
authors.initials: HY
authors.lastname: Lee
authors.affiliation: Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Huang
authors.affiliation: Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Chyi-Liang
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Yi-Hsin
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Chee-Jen
authors.initials: CJ
authors.lastname: Chang
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan; Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan; Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan. Electronic address: chchiu@adm.cgmh.org.tw.
authors.forename: Cheng-Hsun
authors.initials: CH
authors.lastname: Chiu
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D003428:Cross Infection / Q000382:microbiology*; D021901:DNA, Intergenic / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D006801:Humans; D015378:Imipenem / Q000627:therapeutic use*; D007362:Intensive Care Units; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D013624:Taiwan / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D021901:DNA, Intergenic; D015378:Imipenem
keywords: Acinetobacter baumannii; bacteremia; imipenem resistance; mortality; sequence type