Antimicrobial Resistance in Equine Reproduction

Abstract

Bacteria develop resistance to antibiotics following low-level “background” exposure to antimicrobial agents as well as from exposure at therapeutic levels during treatment for bacterial infections. In this review, we look specifically at antimicrobial resistance (AMR) in the equine reproductive tract and its possible origin, focusing particularly on antibiotics in semen extenders used in preparing semen doses for artificial insemination. Our review of the literature indicated that AMR in the equine uterus and vagina were reported worldwide in the last 20 years, in locations as diverse as Europe, India, and the United States. Bacteria colonizing the mucosa of the reproductive tract are transferred to semen during collection; further contamination of the semen may occur during processing, despite strict attention to hygiene at critical control points. These bacteria compete with spermatozoa for nutrients in the semen extender, producing metabolic byproducts and toxins that have a detrimental effect on sperm quality. Potential pathogens such as Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa may occasionally cause fertility issues in inseminated mares. Antibiotics are added during semen processing, according to legislation, to impede the growth of these microorganisms but may have a detrimental effect on sperm quality, depending on the antimicrobial agent and concentration used. However, this addition of antibiotics is counter to current recommendations on the prudent use of antibiotics, which recommend that antibiotics should be used only for therapeutic purposes and after establishing bacterial sensitivity. There is some evidence of resistance among bacteria found in semen samples. Potential alternatives to the addition of antibiotics are considered, especially physical removal separation of spermatozoa from bacteria. Suggestions for further research with colloid centrifugation are provided.

Antimicrobial Resistance in Vaginal Bacteria in Inseminated Mares

“…There are several reports (reviewed recently [ 3 ]) concerning the AMR of bacteria isolated from uterine swabs, uterine lavage, vaginal swabs and clitoral swabs from the equine reproductive tract, mostly in cases of clinical disease or fertility problems. Briefly, resistance among isolates from the reproductive tract of mares has been reported in several countries including France [ 4 ], Sweden [ 5 ], India [ 6 , 7 ], Italy [ 8 , 9 , 10 ], Germany [ 11 ], the US [ 12 , 13 ], Slovakia [ 14 ] and Turkey [ 15 ].…”

Characterization of microbial communities and predicted metabolic pathways in the uterus of healthy mares

“…The WHO warns about A. baumannii and P. aeruginosa as critical microorganisms in terms of their resistance profile ( Allen et al , 2011 ; OMS, 2017 ), species belonging to the same genera found in this research. It is necessary to deepen the knowledge about these microorganisms in the equine and its clinical environment, to elucidate what is the role that they play in the uterine environment of mares and the potential transmission to humans and their environment ( Malaluang et al , 2021 ). On the other hand, Staphylococcus equorum , Shigella sonnei , Arthrobacter ramosus , and P. amygdali were also species with a high relative abundance.…”

Clinical Aspects of Bacterial Distribution and Antibiotic Resistance in the Reproductive System of Equids

“…aeruginosa and S. equi subsp. zooepidemicus may be recovered from those sites, often after mating [ 67 , 68 ]; Cerny et al [ 67 ] indicated that a possibility of bacterial transfer to the stallion’s genital tract during mating could not be excluded.…”

“…and Klebsiella spp. recovered from mares in which artificial insemination was used showed antibiotic resistance more frequently than similar bacteria obtained from non-inseminated animals [ 68 ].…”