Characterization and Identification of Bacterial Flora from Infected Equine Hooves

Abstract

The aim of this research was to characterize and identify the bacterial flora associated with a specific hoof infection in a population of horses in the Rochester NY area. Samples from horses showing symptoms of infection were first grown on Brain-Heart Infusion (BHI) solid medium, a rich medium that allow growth of all bacteria. Forty different bacterial colonies were obtained and characterized microscopically and biochemically. We have identified normal inhabitants of the skin such as Staphylococcus epidermidis, Staphylococcus saprophyticus, Micrococcus varians, and Micrococcus luteus. Bacteria commonly found in soil such as Bacillus megaterium, Bacillus azotoformans, Bacillus insolitus, and Bacillus popilliae were also identified along with Enterococcus faceium, which is found in the gastrointestinal tract of mammals (1, 2, 3). Interestingly bacteria such as Corynebacterium xerosis, known to cause animal diseases were also isolated from infected horses (4). Several of these bacteria were confirmed by sequencing 16S ribosomal DNA. Surprisingly Enterococcus gallinarum, Bacillus subtilis, and Macrococcus were also identified. Bacillus subtilis is commonly found in soil; therefore its presence is understandable. Enterococcus gallinarum is very rare and is found in the intestinal tract of mammals. One species of Macrococcus, Macrococcus epuipercicus, has been found on horse’s skin (5). The bacteria responsible for the hoof infection have yet to be identified, although it is hypothesized that the bacteria are anaerobic and prefer moist environments.