To what extent does Antimicrobial Resistance in Equine Gut E. coli reflect individual veterinary histories?

Abstract:

Goal

The aim of this investigation is to examine the antibiotic resistance profile of E. coli strains isolated from retired racehorses in Hong Kong.

Background

Escherichia coli is a Gram-negative, facultative anaerobic enterobacterium present in the guts of most warm-blooded animals. Because it is so widespread and because bacteria exchange genetic material very readily, E. coli can be used as an indicator species for levels of antibiotic resistance within the gut microbiome. Antimicrobial resistance (AMR) is a growing problem because it makes infections harder to treat in human and animal medicine. The extensive use of antibiotics in human medicine helps to select for resistant strains and their use in veterinary medicine (and in intensive farming) magnifies this effect.

Method

This study investigates a sample of retired racehorses in Hong Kong (mean age 11 years), which have received close and documented veterinary care since being imported. Faecal samples were screened using 3M™ Petrifilm™ E. coli/coliform plates and selected isolates were then passaged on LB agar plates for at least ten times. Antibiotic susceptibility was tested (initially against ampicillin, tetracycline and kanamycin) and DNA extracted using an Invitrogen PureLink Genomic DNA Mini Kit and sequenced via the Illumina MiSeq platform. The RGI (Resistance Genes Identifier) at CARD (The Comprehensive Antibiotic Resistance Database) was used to locate AMR genes and these profiles compared with veterinary records.