Biofilm: is it real and how do we manage it in equine reproduction

Bacteria utilize numerous methods to survive degradation by the host immune system and antibiotic therapy. One survival tool utilized by bacteria is the production of a biofilm. Biofilms allow bacteria to be unrecognized by the host immune system, prevent exposure to antibiotics, and allow for exchange of genetic material leading to antibiotic resistance. Until recently very little was known about the importance of biofilm in cases of equine endometritis. Recent studies have identified bacteria residing in a biofilm on the endometrial surface of mares using a model of endometritis. Currently there is not a good diagnostic technique for detecting a biofilm associated infection in clinical practice. Clinicians should strongly suspect a biofilm in mares that are identified to have an infection, appropriate treatment is applied to the case and the infection is not readily cleared. Biofilm infections have a high rate of failure due to the bacteria being protected from antibiotics by being in the biofilm lifestyle. Non-antibiotics can be effectively used to disrupt the biofilm that is protecting the bacteria allowing antibiotic treatments to effectively eradicate the infection. Caution should be used when mixing antibiotics with non-antibiotics as many were found to result in inactivation of the antibiotics used in the treatment. Commonly used effective compounds are presented in Table 1. Overall the incidence of biofilm or latent bacteria is unknown in the broodmare population. However, with overall pregnancy rates in the broodmare population being relatively high per cycle it is suspected that the incidence rate of biofilm or latent bacteria is low. In individual mares failing to become pregnant biofilm and latent bacteria should be a consideration as a cause of subfertility. Fortunately, research has described how these infections might develop, improved diagnostic techniques and effective treatment strategies for biofilm or latent bacterial endometritis.

[...]