Escherichia coli multilocus sequence type 38 from humans and broiler production represent distinct monophyletic...

Area of Science:

• Microbiology
• Genomics
• Antimicrobial Resistance

Background:

• Escherichia coli ST38 is a significant cause of human extra-intestinal infections, often exhibiting resistance to extended-spectrum cephalosporins (ESCs).
• OXA-244-mediated carbapenem resistance has been reported in E. coli ST38, prompting investigation into its source.
• E. coli ST38 is prevalent in broiler production and frequently resistant to ESCs.

Purpose of the Study:

• To analyze the genetic characteristics and evolutionary relationship of E. coli ST38 isolates from human and broiler sources.
• To determine if there is evidence of spillover of E. coli ST38 between human and broiler populations.
• To investigate the genetic basis for resistance, particularly the presence of blaOXA-244, in these distinct populations.

Main Methods:

• Whole-genome sequencing of 288 E. coli ST38 isolates.
• Phylogenetic analysis to determine the relationship between human and broiler isolates.
• Comparative analysis of antimicrobial resistance genes, including blaOXA-244, across different sources.

Main Results:

• Phylogenetic analysis revealed distinct monophyletic clades for human and broiler-associated E. coli ST38.
• Differences in ESC resistance genes were observed between isolates from the two sources.
• The blaOXA-244 gene was not detected in E. coli ST38 isolates from broiler production.

Conclusions:

• E. coli ST38 isolates from human and broiler production represent well-separated genetic lineages.
• The increasing prevalence of OXA-244-producing E. coli ST38 in humans is unlikely to be associated with a spillover event from broiler production.