Microbial Prevalence and Antimicrobial Sensitivity in Equine Endometritis in Field Conditions

SIMPLE SUMMARY: Endometritis diagnosis can be achieved by means of an endometrial biopsy and/or swab, the latter being used for cytology and microbiologic evaluation. Endometrial culturing plus a sensitivity test are crucial in infectious endometritis in order to determine the causal microorganism as well as the best antimicrobial treatment. In this study, endometrial swabs for culture and sensitivity test were obtained from 363 mares with reproductive failure. The most isolated microorganism was Escherichia coli, followed by Staphylococcus spp. and Streptococcus spp. Regarding sensitivity tests, the most efficient antibiotics were amikacin, cefoxitin and gentamicin, whereas cephaloridine and penicillin showed the lowest indexes. It can be concluded that, under the conditions of this study, β-lactam antibiotics are not efficient as a treatment for equine endometritis. In addition, microbiological and sensitivity studies are crucial to obtain good results when treating equine endometritis. ABSTRACT: Endometritis is one of the main causes of infertility in mares. In the present study, 363 mares with a history of repetitive infertility, and positive endometrial cytology and/or vaginal discharge were included. An endometrial swab for microbiological purposes plus sensitivity test was obtained from each mare. A positive culture was obtained in 89% of mares. The main isolated genera were Staphylococcus (25.1%), Streptococcus (18.2%), Escherichia (17.3%) and Pseudomonas (12.1%). With regard to species, the most isolated microorganism was Escherichia coli (17.3%), Staphylococcus spp. (15.6%) and Streptococcus spp. (13.5%). Sensitivity tests showed that the most efficient antimicrobial was amikacin (57.3% of cultures), followed by cefoxitin (48.6%) and gentamicin (48.3%). When sensitivity test was analyzed in terms of Gram+ and Gram– bacteria, Gram+ were highly resistant to cephaloridine (77.3% of cultures), apramycin (70.8%) and penicillin (62.3%), whereas Gram– were highly resistant to penicillin (85.8%), followed by cephaloridine (78.9%). In conclusion, the present study shows the most prevalent microorganisms isolated from equine endometritis, which were found to be resistant to β-lactam antimicrobials. Likewise, these results highlight the significance of performing microbiological analyses as well as sensitivity tests prior to applying an antimicrobial therapy.