Antimicrobial resistance trends among Salmonella isolates obtained from horses in the northeastern United States (2001-2013).

The article discusses the trends in antimicrobial resistance in Salmonella strains isolated from horses in the northeastern part of the United States, over a span of 13 years (2001-2013). The findings suggest that although the prevalence of antimicrobial resistance varies, it is not increasing, implying that the current use of antimicrobials in horses is not contributing to the development and spread of drug-resistant Salmonella.

Research Methodology

• The study conducted retrospectively, collected data from Salmonella samples obtained from horse specimens that were submitted to the Cornell University Animal Health Diagnostic Center from January 2001 to December 2013.
• The resistance trends for thirteen specific antimicrobials were analyzed over time using the Cochran-Armitage trend test.

Key Findings

• The resistance to different antimicrobials varied, with 0% for imipenem and 51.5% for chloramphenicol.
• Over the research period, the prevalence of resistance decreased significantly for seven of the thirteen observed antimicrobials: amoxicillin-clavulanic acid, ampicillin, cefazolin, cefoxitin, ceftiofur, chloramphenicol, and tetracycline.
• The susceptibility to all thirteen antimicrobials was determined for 337 isolates, revealing that 40.9% were pansusceptible (sensitive to all drugs) and 57% were multidrug resistant (resistant to three or more classes of drugs).
• The most commonly discovered serovar was Salmonella Newport. Despite its prevalence decreasing notably over time, this did not substantially impact the overall observed antimicrobial resistance trends.

Conclusions and Clinical Relevance

• The study concludes that current antimicrobial practices in horses in this region are not driving the emergence and spread of drug-resistant strains of Salmonella.
• These results have significant implications for veterinary practices, reinforcing the importance of judicious use of antibiotics to prevent the development of drug resistance.
• The monitoring of antimicrobial resistance patterns is crucial in informing effective treatment strategies and antibiotic stewardship programs in veterinary medicine.