The prevalence of colistin resistance in Escherichia coli and Klebsiella pneumoniae isolated from food animals in China: coexistence of mcr-1 and blaNDM with low fitness cost

Int J Antimicrob Agents. 2018 May;51(5):739-744. doi: 10.1016/j.ijantimicag.2018.01.023. Epub 2018 Jan 31.

Abstract

Increasing colistin resistance is a global concern because colistin is used as a last resort for the treatment of carbapenem-resistant Enterobacteriaceae infections. The plasmid-mediated colistin resistance gene, mcr-1 was found in distinct bacterial species isolated from humans, animals, and the environment. In this study, farms in four different agricultural provinces in China were investigated to determine the occurrence of the antimicrobial resistance and related genes. A total of 373 Escherichia coli and 54 Klebsiella pneumoniae were isolated from 510 non-duplicated samples. Of the E. coli and K. pneumoniae isolates, 72.7% and 66.7%, respectively, were susceptible to colistin. Isolates resistant to colistin comprised 46.6% of the samples isolated from Shandong, and 17.8% and 16.4% of the samples from Jilin and Henan, respectively. Twenty-six carbapenem-resistant E. coli isolates were resistant to colistin, in which both mcr-1 and blaNDM were present. Specifically, the co-existence was found in isolates from animals and sewage. Most of the resistance genes were located on plasmids and were 40-244 kilobases. Growth curves of transconjugants carrying mcr-1, blaNDM-1, blaNDM-4, blaNDM-5, and blaNDM-9 showed a low fitness cost compared with the recipient. In conclusion, mcr-1 was widespread in E. coli and K. pneumoniae isolated from farms in China. Co-existence of mcr-1 and blaNDM-9 was identified in different sequence types of E. coli with low fitness cost from various origins, indicating an urgent need to take measures for decreasing dissemination.

Keywords: Fitness cost; Food animals; Sewage; bla(NDM); mcr-1.

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • China
  • Colistin / pharmacology*
  • Drug Resistance, Bacterial / drug effects
  • Drug Resistance, Bacterial / genetics*
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli Proteins / genetics
  • Farms
  • Genetic Fitness
  • Klebsiella pneumoniae / drug effects*
  • Klebsiella pneumoniae / isolation & purification
  • Livestock / microbiology*
  • Microbial Sensitivity Tests
  • Prevalence
  • beta-Lactamases / genetics

Substances

  • Bacterial Proteins
  • Escherichia coli Proteins
  • MCR-1 protein, E coli
  • beta-Lactamases
  • Colistin