A Novel Phenotypic Method To Screen for Plasmid-Mediated Colistin Resistance among Enterobacteriales

J Clin Microbiol. 2019 Apr 26;57(5):e00040-19. doi: 10.1128/JCM.00040-19. Print 2019 May.

Abstract

Plasmid-mediated colistin resistance (PMCR), a consequence of the mcr genes, is a significant public health concern given its potential to easily spread among clinical pathogens. Recently, it was discovered that MCR enzymes require zinc for activity. Thus, we modified the colistin broth-disk elution (CBDE) test to screen for plasmid-mediated colistin resistance (PMCR) genes based on any reduction of colistin MIC in the presence of EDTA. Eighty-five isolates of the order Enterobacteriales (12 mcr positive) were tested by CBDE ± EDTA. The sensitivity and specificity of the EDTA-CBDE method to detect PMCR compared to the molecular genotype results were 100% and 95.8%, respectively. Isolates positive by the EDTA-CBDE test should be further evaluated to confirm the presence of mcr genes.

Keywords: colistin; mcr; phenotypic method; plasmid-mediated colistin resistance.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Colistin / pharmacology*
  • Drug Resistance, Bacterial*
  • Edetic Acid
  • Enterobacteriaceae / drug effects*
  • Enterobacteriaceae / genetics
  • Genes, MDR
  • Microbial Sensitivity Tests / methods
  • Phenotype
  • Plasmids / genetics
  • Sensitivity and Specificity

Substances

  • Anti-Bacterial Agents
  • Edetic Acid
  • Colistin