Genomic background of a colistin-resistant and highly virulent MCR-1-positive Escherichia coli ST6395 from a broiler chicken in Pakistan

Abstract

The convergence of high virulence and multidrug resistance (MDR) in Gram-negative pathogens circulating at the human-animal interface is a critical public health issue. We hereby report the genomic characteristics and virulent behavior of a colistin-resistant Escherichia coli, serotype ONT:H26, belonging to ST6395, isolated from a healthy broiler in Pakistan. This strain harbored multiple antimicrobial resistance genes, including mcr-1.1 and blaCARB-2, besides cma (colicin M) and astA [heat-stable enterotoxin 1 (EAST1) toxin] virulence genes. In vivo experiments carried out with the Galleria mellonella infection model revealed that MCR-1-positive E. coli ST6395 killed 96.4% of the larvae at 18 hour post-infection. Interplay between resistance and virulence in clinically important pathogens could be a potential threat, representing a serious challenge to global public health.

Keywords: Galleria mellonella; WGS; poultry; resistome; colistin resistance; virulome.