Multiple Antimicrobial Resistance in Horses

drug resistance horses, british equine veterinary association, multiple drug resistance equine levels

By Mark Andrews

Multiple drug resistance (MDR) among bacteria isolated from equine clinical samples is at a concerning level, according to work presented at the recent British Equine Veterinary Association conference.

Cajsa Isgren and colleagues at the University of Liverpool examined antibiotic susceptibility test results from over 3000 bacterial isolates cultured from swabs taken from equine clinical cases. The tests had been performed at six large equine diagnostic laboratories.

Resistance to at least one class of antimicrobial was present in 89.0 percent of Gram-positive and 68.9 percent of Gram-negative isolates. 

MDR (resistance to three or more different classes of antimicrobial) was present in 34.9 percent of isolates. MDR was more common in Gram-positive than Gram-negative bacteria. The most common sources of multiple drug resistant bacteria were catheter insertion sites and surgical site infections.

Newer antibacterials were not exempt from resistance. Resistance to third/fourth generation cephalosporins was found in 28.1 percent of Gram-negative isolates. Fluoroquinolones resistance was present in 12.5 percent of relevant isolates.

The authors stress the importance of ongoing surveillance to monitor changing patterns of resistance and promote antimicrobial stewardship in equine practice.

For more details, see: Antimicrobial resistance surveillance from clinical submissions in UK horses.

Published with permission of Mark Andrews, Equine Science Update.

Photo: Scientist’s hand holding petri plate infected with bacteria Staphylococcus Aureus, Moraxella Catarrhalis bacteria on white background. Credit: Shutterstock/Monika Wisniewska