Antimicrobial susceptibility and molecular epidemiology of clinical Enterobacter cloacae bloodstream isolates in Shanghai, China

PLoS One. 2017 Dec 15;12(12):e0189713. doi: 10.1371/journal.pone.0189713. eCollection 2017.

Abstract

Background: Enterobacter cloacae is a major nosocomial pathogen causing bloodstream infections. We retrospectively conducted a study to assess antimicrobial susceptibility and phylogenetic relationships of E. cloacae bloodstream isolates in two tertiary university-affiliated hospitals in Shanghai, in order to facilitate managements of E. cloacae bloodstream infections and highlight some unknowns for future prevention.

Methods: Fifty-three non-duplicate E. cloacae bloodstream isolates were consecutively collected from 2013 to 2016. Antimicrobial susceptibility was determined by disk diffusion. PCR was performed to detect extended-spectrum β-lactamase (ESBL), carbapenemase and colistin resistance (MCR-1) gene. Plasmid-mediated AmpC β-lactamase (pAmpC) genes were detected using a multiplex PCR assay targeting MIR/ACT gene (closely related to chromosomal EBC family gene) and other plasmid-mediated genes, including DHA, MOX, CMY, ACC, and FOX. eBURST was applied to analyze multi-locus sequence typing (MLST).

Results: The rates of resistance to all tested antibiotics were <40%. Among 53 E. cloacae isolates, 8(15.1%) were ESBL producers, 3(5.7%) were carbapenemase producers and 18(34.0%) were pAmpC producers. ESBL producers bear significantly higher resistance to cefotaxime (100.0%), ceftazidime (100.0%), aztreonam (100.0%), piperacillin (87.5%), tetracycline (75.0%), and trimethoprim-sulfamethoxazole (62.5%) than non-producers (p<0.05). PAmpC- and non-producers both presented low resistance rates (<40%) to all antibiotics (p>0.05). SHV (6/8, 75.0%) and MIR/ACT (15/18, 83.3%) predominated in ESBL and pAmpC producers respectively. Moreover, 2 isolates co-carried TEM-1, SHV-12, IMP-26 and DHA-1. MLST analysis distinguished the 53 isolates into 51 STs and only ST414 and ST520 were assigned two isolates of each (2/53).

Conclusion: The antimicrobial resistance rates were low among 53 E. cloacae bloodstream isolates in the two hospitals. Multiclonality disclosed no evidence on spread of these isolates in Shanghai. The simultaneous presence of ESBL, carbapenemase and pAmpC detected in 2 isolates was firstly reported in Shanghai, which necessitated active ongoing surveillances and consistent prevention and control of E. cloacae.

MeSH terms

  • Bacterial Proteins / genetics
  • China / epidemiology
  • Cross Infection / drug therapy*
  • Cross Infection / epidemiology
  • Cross Infection / genetics
  • Cross Infection / microbiology
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Enterobacter cloacae / genetics*
  • Enterobacter cloacae / pathogenicity
  • Ethanolaminephosphotransferase / genetics
  • Humans
  • Molecular Epidemiology*
  • Phylogeny
  • beta-Lactamases / genetics

Substances

  • Bacterial Proteins
  • Ethanolaminephosphotransferase
  • beta-Lactamases
  • carbapenemase

Grants and funding

This work was supported by the Special Fund for Health-scientific Research in the Public Interest of China Program (201002021) to Yu-Xing Ni, the National Natural Science Foundation of China (81472010) to Yu-Xing Ni and the Shanghai Three-Year Plan of the Key Subjects Construction in Public Health-Infectious Diseases and Pathogenic Microorganism (15GWZK0102). The funders had no role in study design, data collection and analysis, preparation of the manuscript or decision for publication.