title: Acinetobacter calcoaceticus from a fatal case of pneumonia harboring bla(NDM-1) on a widely distributed plasmid.
abstract: BACKGROUND
  We have recovered one bla(NDM-1)-harboring bacterial strain, designated as XM1570, from a sputum sample obtained from a fatal case of pneumonia in China.
  
  
  METHODS
  Biochemical profiling, 16S rRNA sequencing and antimicrobial susceptibility testing were performed. Conjugation experiments were conducted to determine transmissibility of resistance. Pulsed-field gel electrophoresis and whole genome sequencing were performed to identify strain-specific features.
  
  
  RESULTS
  The isolate XM1570 was identified as Acinetobacter calcoaceticus. Whole genome sequencing identified two plasmids, pXM1 and pXM2. Comparative analysis showed >99% similarity between XM1570 and A. calcoaceticus PHEA-2. Plasmid pXM1 carried the carbapenemase gene bla(NDM-1) and displayed high homology with previously described plasmids isolated from different Acinetobacter spp., which were collected from human or livestock distributed in China and worldwide. The bla(NDM-1) gene was located on this conjugative plasmid in a transposon-like region flanked by two copies of the insertion sequence ISAba125; and resistance to all tested β-lactams was observed. Transferability of resistance from pXM1 to the transconjugants was identified. Plasmid pXM2 had an insertion sequence ISAba125 and a -35 region of the bla NDM-1 gene promoter but the bla NDM-1 gene was not present. A chromosomally located carbapenemase-encoding gene bla OXA-75 was detected; however, this gene was interrupted by an insertion sequence ISAba22 belonging to IS3 family.
  
  
  CONCLUSIONS
  Location of bla(NDM-1) on different self-transmissible plasmids could facilitate geographically broad dissemination and host range expansion of the bla(NDM-1) gene via horizontal gene transfer. Our findings of this normally environmental species A. calcoaceticus XM1570 further underline the significant clinical challenge and the essential need for surveillance including molecular methods and plasmid analyses.
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. jiekenlee@126.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. jettyang@163.com.
authors.forename: Chaojie
authors.initials: C
authors.lastname: Yang
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. joycesuete122@gmail.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Xie
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. anan160@126.com.
authors.forename: Nan
authors.initials: N
authors.lastname: Liu
authors.affiliation: 174th Hospital of PLA, Xiamen, Fujian, China. wanghouzhao@126.com.
authors.forename: Houzhao
authors.initials: H
authors.lastname: Wang
authors.affiliation: 174th Hospital of PLA, Xiamen, Fujian, China. zhanglinghubei@163.com.
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. wx1985_324@163.com.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. ywang40@hotmail.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. qiushf0613@hotmail.com.
authors.forename: Shaofu
authors.initials: S
authors.lastname: Qiu
authors.affiliation: Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 DongDa Street, Fengtai District, Beijing, 100071, China. hongbinsong@263.net.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Song
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000382:microbiology; D016954:Acinetobacter calcoaceticus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002681:China; D004251:DNA Transposable Elements; D016521:Electrophoresis, Gel, Pulsed-Field; D017809:Fatal Outcome; D022761:Gene Transfer, Horizontal; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D018410:Pneumonia, Bacterial / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017423:Sequence Analysis, RNA; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D012336:RNA, Ribosomal, 16S; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1