Background
Group B Streptococcus (GBS) is a major human and animal pathogen. Host-generalist GBS lineages, which can colonize and/or infect multiple hosts, represent a potential threat to public health. We have shown that the most common host-generalist lineage in Brazil is clonal complex (CC) 103, which has circulated in cattle and humans since 1990s. In the later, though, CC103 has been detected only in carriage samples. Here we report the detection of CC103 causing severe infections in primate and humans in Brazil.
Methods
GBS strains belonging to our collection and isolated from disease cases since 2023 in Brazil were screened by determining serotype and ST.
Results
Two GBS strains recovered from adult human disease (vulvar abscess or knee prosthetic), as well as one GBS isolate associated with spontaneous miscarriage in a Macaca mulatta (Rhesus monkey) belonged to CC103-Ia. This animal had a history of vaginal prolapse, stillbirth and premature birth, and was part of a scientific breeding facility with daily human contact. While both human GBS were ST103, the monkey GBS was ST485, a DLV of ST103 never detected before in Brazil.
Conclusion
The GBS host-generalist CC103-Ia lineage, which is widespread in Brazil since 1990s as a bovine mastitis agent and colonizer of pregnant women, is also able to cause severe or invasive disease in primates and humans. The finding of a novel CC103 variant (ST485) causing miscarriage in non-human primate suggests an ongoing evolution of this lineage which may lead to the emergence of highly virulent strains.