Microbial Prevalence and Antimicrobial Sensitivity in Equine Endometritis in Field Conditions.
Authors: Díaz-Bertrana María Luisa, Deleuze Stefan, Pitti Rios Lidia, Yeste Marc, Morales Fariña Inmaculada, Rivera Del Alamo Maria Montserrat
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Endometrial infection represents a leading cause of reproductive failure in mares, yet treatment decisions are frequently made without microbiological guidance. Díaz-Bertrán and colleagues cultured endometrial swabs from 363 subfertile mares with cytological and/or clinical evidence of endometritis, performing concurrent antimicrobial sensitivity testing on all isolates. Positive cultures were obtained in 89% of cases, with Staphylococcus, Streptococcus, Escherichia and Pseudomonas dominating the microbial landscape; E. coli alone accounted for 17.3% of infections. Critically, β-lactam antimicrobials—traditionally relied upon in equine practice—showed disappointing efficacy, with penicillin resistance exceeding 62% in Gram-positive organisms and 86% in Gram-negative isolates; amikacin demonstrated superior activity at 57.3% sensitivity across all cultures. These findings underscore the clinical importance of obtaining endometrial samples with antimicrobial susceptibility testing before initiating therapy, rather than deploying empirical broad-spectrum regimens that risk both therapeutic failure and antibiotic resistance development.
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Practical Takeaways
- •Culture and sensitivity testing are essential before treating equine endometritis, as β-lactam antimicrobials show poor efficacy against prevalent organisms
- •Avoid empirical penicillin therapy; amikacin, cefoxitin, or gentamicin are more likely to be effective based on this prevalence data
- •Nearly 9 in 10 subfertile mares with endometrial cytology findings will have positive bacterial cultures, justifying microbiological investigation in repetitively infertile mares
Key Findings
- •Positive bacterial culture obtained in 89% of 363 mares with repetitive infertility and endometrial cytology/vaginal discharge
- •Most prevalent genera were Staphylococcus (25.1%), Streptococcus (18.2%), Escherichia (17.3%), and Pseudomonas (12.1%)
- •Amikacin demonstrated highest antimicrobial efficacy (57.3%), followed by cefoxitin (48.6%) and gentamicin (48.3%)
- •Gram-positive bacteria showed high resistance to cephaloridine (77.3%), apramycin (70.8%), and penicillin (62.3%); Gram-negative highly resistant to penicillin (85.8%)