Survival of Streptococcus equi subsp. equi in Normal Saline Versus Phosphate-Buffered Saline and at Two Different Temperatures.

Streptococcus equi subsp. equi causes strangles in horses. Sampling to detect carriers is important for the control of the disease, and maximizing the sensitivity of this procedure is necessary. To provide a basis for the choice of sampling solution and transport temperature for samples, comparisons were made between the survival of Streptococcus equi subsp. equi in normal saline versus phosphate-buffered saline and at two different temperatures (cold and room temperature). At present, normal saline is used to sample the nasopharynx as well as the guttural pouches, and the sampling solution is transported without special cooling. The results revealed no significant difference in bacterial concentration levels between the two sampling solutions, but a significantly higher concentration of viable bacteria in the samples kept cold compared with room temperature. Hence, a change of sampling solution is not warranted, but maintaining the cold chain during storage and transport to the laboratory may be important for clinical samples.