Group B Streptococcus sequence type 103 is known primarily as a bovine mastitis pathogen. In Brazil, it has circulated in cattle and humans since the 1990s. It lacks scpB and, in humans, was found only among carriage isolates. Bovine-human interspecies transmission may have contributed to its evolution and spread.
Keywords: Brazil; Group B Streptococcus; Streptococcus agalactiae; bacteria; bovine mastitis; cattle; humans; molecular epidemiology; streptococci; zoonoses.