Streptococcus equi subspecies equi (S. equi) is the causative agent of strangles, a contagious respiratory disease of horses. Transmission of the bacteria can occur when animals share water sources. Detection of S. equi in water could improve strangles surveillance and move towards eradication of the disease. The aims of this study were to determine the optimal membrane pore size for bacterial retention from an aqueous suspension, to determine the likely dispersion pattern of S. equi contaminated mucus in a water bucket to develop a collection technique to be used by veterinarians, and to find the sensitive range for S. equi detection in water. Samples from the top, middle, and bottom of a five-gallon water bucket were collected by aspiration and swabbing, and streptococci harvested by filtration. Mucus strands remained suspended at the top, middle, and bottom the bucket for over an hour. Membrane filters with pore sizes of 0.45 μm were found to retain all streptococci. After one hour, viable S. equi were obtained predominantly from the top and middle of the bucket. The threshold for detection lies between 10 C.F.U./mL and 0.1 C.F.U./ mL. Membrane filtration of water from the top two thirds of a bucket proved to be the most sensitive sampling technique. However, the technique requires validation in the field.
McLaughlin, Lily A., "Improved Detection of Streptococcus Equi Subspecies Equi in Drinking Water" (2014). Honors College. 141.