title: [Analysis of the carbapenemase-producing mechanism of Enterobacteriaceae with decreased susceptibility to carbapenems].
abstract: OBJECTIVE
  To analyze the distribution of Enterobacteriaceae isolated from West China Hospital, investigate the antibiotic resistance profile of Enterobacteriaceae with decreased susceptibility to carbapenems and explore the molecular mechanism.
  
  
  METHODS
  Forty-five Enterobacteriaceae strains resistant or with reduced susceptibility to carbapenems were isolated from patients in West China Hospital. The antimicrobial susceptibility and carbapenemase-producing phenotypes of the bacteria were examined and specific PCR were performed to determine the molecular mechanism.
  
  
  RESULTS
  Of the 45 isolates, 17, 21 and 36 were resistant or intermediate strains to imipenem, meropenem and ertapenem, respectively. The majority of these isolates showed resistance to cephalosporins. The modified Hodge test resulted in the highest positivity rate (77.8%), followed by EDTA disc test (57.8%) and PBA disc test (22.2%). BlaTEM, blaSHV and blaCTX-M were detected in 60.0%, 53.3% and 15.6% of these strains with reduced susceptibility. The rate of strains carrying 2 or more genes was 44.4%, and the detection rate of blaIMP was 48.9%. BlaKPC was identified in 4 (8.9%) high-level resistant strains and confirmed to locate on the plasmid.
  
  
  CONCLUSIONS
  Production of carbapenemase contributes to reduced susceptibility of carbapenems in Enterobacteriaceae. The presence of blaKPC, MBL and ESBL, and their possible combinations can be the main factor contributing to carbapenem resistance or reduced susceptibility in Enterobacteriaceae. The KPC-2 carbapenemase gene located on the plasmids we found in this study can cause potential horizontal transmission across strains.
authors.affiliation: Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, China.E-mail: tingting2003.1@163.com.
authors.forename: Tingting
authors.initials: T
authors.lastname: Wang
authors.forename: Dongdong
authors.initials: D
authors.lastname: Li
authors.forename: Chuanmin
authors.initials: C
authors.lastname: Tao
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Mei
authors.initials: M
authors.lastname: Kang
authors.forename: Zhixing
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D000077727:Ertapenem; D005784:Gene Amplification; D015378:Imipenem / Q000494:pharmacology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013845:Thienamycins / Q000494:pharmacology; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D013845:Thienamycins; D047090:beta-Lactams; D015378:Imipenem; C491478:beta-lactamase KPC-2; D001618:beta-Lactamases; C063912:carbapenemase; D000077731:Meropenem; D000077727:Ertapenem