Strain differentiation of isolates of streptococci from bovine mastitis by pulsed-field gel electrophoresis

Abstract

Pulsed-field gel electrophoresis (PFGE) was examined as a tool to differentiate strains of streptococci isolated from clinical and sub-clinical cases of bovine mastitis. Analysis of Smal chromosomal digests of Streptococcus agalactiae, S. dysgalactiae subsp. dysgalactiae and S. uberis isolates revealed intraherd and interherd strain relationships within each species. Comparison of S. agalactiae isolates from the same herd revealed little variability in their Smal restriction patterns indicating a single strain originating from a common source of infection. However, comparison of S. agalactiae isolates between herds showed that each herd was infected with a distinct strain. The restriction pr..