bla SED-1 beta-lactamase-producing Citrobacter sedlakii isolated from horses and genomic comparison with human-derived isolates

J Appl Microbiol. 2024 Nov 4;135(11):lxae278. doi: 10.1093/jambio/lxae278.

Abstract

Aims: We aim to detect beta-lactamase-producing Citrobacter sedlakii from horses and compare the genomic characteristics with isolates from humans.

Methods and result: We characterized phenotypically and genotypically nine C. sedlakii isolates from the feces of horses and then compared them to human-derived isolates using whole genome sequencing and phylogenomic methods. Seven isolates (7/9) were ampicillin-resistant, while at least one isolate was resistant to ceftriaxone, gentamicin, meropenem, and streptomycin. All nine isolates were carriers of the chromosomal-mediated blaSED-1 beta-lactamase gene, which confers resistance to ampicillin. One isolate was positive for the mcr-9 gene that confers resistance to colistin, and another isolate had the aac(6')-lid gene that confers resistance to aminoglycosides. Seven isolates (7/9) were carriers of genes that confer metal resistance to copper, silver, and arsenic. Phylogenetically, two horse-derived isolates clustered together with two human-derived isolates from the NDARO database.

Conclusion: The results from our study provide insight into the antimicrobial susceptibility of C. sedlakii in horses, which was previously lacking, and the specific beta-lactamase gene mediating resistance.

Keywords: Citrobacter sedlakii; bla SED-1; antimicrobial resistance; horse.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Anti-Bacterial Agents* / pharmacology
  • Citrobacter* / drug effects
  • Citrobacter* / enzymology
  • Citrobacter* / genetics
  • Citrobacter* / isolation & purification
  • Drug Resistance, Multiple, Bacterial / genetics
  • Enterobacteriaceae Infections / microbiology
  • Enterobacteriaceae Infections / veterinary
  • Feces* / microbiology
  • Genome, Bacterial
  • Horse Diseases / microbiology
  • Horses / microbiology
  • Humans
  • Microbial Sensitivity Tests*
  • Phylogeny*
  • Whole Genome Sequencing
  • beta-Lactamases* / genetics

Substances

  • beta-Lactamases
  • Anti-Bacterial Agents