The influence of antimicrobial agents on the development of antibiotic resistance in the vaginal bacterial flora of artificially inseminated mares

• Main Author: Wilén, Elin
• Format: Text
• Language: Swedish; English
• Published: 2021
• Subjects: Animal diseases; Northern Sweden
• Online Access: https://stud.epsilon.slu.se/16452/1/wilen_elin_210118.pdf

In Sweden and in many other countries, artificial insemination (AI) is frequently used in horse breeding. The technology makes it possible to use genetic material from horses in different geographical locations in an effective way, minimizing the risk of infection or even injury to both horses and stud personnel. Semen collection is performed with a high hygienic standard but despite this, it is seldom possible to obtain an ejaculate that does not contain bacteria. Bacteria in the ejaculate can cause disease in the mare, or result in a deterioration in sperm quality, thereby reducing the chance of the mare becoming pregnant after insemination. To ensure disease control and maintain sperm quality, addition of antibiotics to the semen is therefore required to reduce the number of bacteria in the ejaculate. To protect the spermatozoa during storage, a semen extender containing both buffering and nutrient-rich components, but also antimicrobial substances (AMS) is added. During insemination, the semen dose is deposited in the mare's uterus, which initiates a response from the local immune system. This results in an immunological and mechanical cleansing of the deposited material through the cervix uteri, which is an important function for maintaining a healthy uterine environment and enabling a pregnancy. The mare's vaginal bacterial flora is therefore exposed to the antibiotics contained in the extender, which could theoretically increase the risk of developing antibiotic resistance in the bacterial flora. In this study, vaginal swabs were obtained from 39 mares of varying breeds and ages in northern Sweden, with the aim of investigating the normal vaginal bacterial flora and how its resistance pattern is affected by the exposure to the antibiotics (penicillin and gentamicin) contained in the semen extender INRA-96, and if resistant bacteria are present in the normal vaginal flora of mares. The mares were categorized into either an exposed group consisting of breeding mares at a stud farm, or a control group ...