Temporal efficacy of antimicrobials against aerobic bacteria isolated from equine endometritis: An Italian retrospective analysis (2010-2017)

This study aimed to describe bacteria isolated from the reproductive tract of mares and to identify changes in antimicrobial susceptibility patterns to those antibiotics commonly used for the treatment of equine endometritis. A total of 4122 equine uterine swabs were collected from mares suffering from reproductive tract disorders in the period 2010-2017. Aerobic culture and antimicrobial susceptibility testing using agar disk diffusion was performed on each sample. Aerobic bacteria were isolated from 3171/4122 (76.9%) samples. The most frequently isolated microorganisms were Escherichia coli (885/3171, 27.9%) and Streptococcus equi subsp. zooepidemicus (791/3171, 24.9%), confirming previous findings from the literature. Antimicrobial susceptibility patterns of E. coli, S. equi subsp. zooepidemicus and Klebsiella pneumoniae changed over time . A statistically significant decrease of antimicrobial efficacy of cefquinome against E. coli was observed over the years as well as of ampicillin, cefquinome and penicillin against S. equi subsp. zooepidemicus. The high frequency of resistant bacteria isolated in the present work proceeds in the same way as indicated by surveillance data on the huge antibiotic use in Italy. As a result, testing and monitoring programs of antimicrobial efficacy are crucial to consciously using antibiotics and preserving their effectiveness both for veterinary and human medicine.