Genetic Relatedness Among Streptococcus agalactiae Isolated from Cattle, Fish, and Humans.

Abstract

Streptococcus agalactiae is well recognized to cause a variety of infections in many animal species and humans. We aimed to investigate genetic relatedness of S. agalactiae strains isolated from humans and animal origins, including cattle and fish, using capsular gene typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing techniques. Our results revealed that S. agalactiae strains with capsular type Ia and ST103 were observed from all bovine isolates (17/17) and one human isolate (1/5). S. agalactiae strains with capsular type III and ST283 were detected among isolates from fish (5/5) and from humans (2/5). Two PFGE clusters containing isolates from mixed origins were demonstrated: one cluster of five fish and one human isolate, and another cluster of one bovine and one human isolate. In conclusion, the close genetic relationship among S. agalactiae strains isolated from humans and animal origins was evident.