Analysis of Risk Factors Associated with Antibiotic-Resistant Escherichia coli

Antimicrobial-resistant bacteria represent a major threat to human and animal health. We compared equine fecal samples ( n =264) from 138 horses from hospital and nonhospital (livery stable and riding school) premises in North West England to determine the prevalence of Escherichia coli , Salmonella , and Campylobacter and rates of antimicrobial-resistant E. coli strains. Campylobacter jejuni was detected only in hospitalized horses (1.1%), and no Salmonella was identified. Data analysis of the horses' management and veterinary treatments (Tx) identified risk factors associated with shedding of antimicrobial-resistant E. coli . The hospital was the major source of resistant and multi-drug-resistant (MDR) E. coli . Moreover, shedding of antimicrobial-resistant E. coli was associated significantly with hospitalization for a gastrointestinal problem (odds ratio [OR]:±95% confidence intervals=8.50:1.79–40.32), receipt of oral antimicrobial Tx (OR=3.52:1.11–11.10), multiple antimicrobial Tx in hospital (OR/Tx=1.05:1.01–1.09), or geldings (OR=4.62:1.23–17.46). Interestingly, intravenous antimicrobial Tx was negatively associated with shedding of antimicrobial-resistant E. coli (OR=0.18:0.04–0.76). MDR E. coli was associated with hospitalization, antimicrobial Tx in hospital (OR/Tx=3.65:1.54–8.68), and increased age (OR/year=1.11:1.03–1.19). Thus, equine hospitals in this geographic location appear to be an important source of antimicrobial-resistant and MDR E. coli strains, but unlikely reservoirs of Salmonella or Campylobacter . Thus, it is important to moderate antimicrobial Tx given to hospitalized horses to lessen exposure and fecal shedding of resistant pathogens.