Phenotypic and genotypic comparison of pathogenic group B Streptococcus isolated from human and cultured tilapia (Oreochromis species) in Malaysia

Group B Streptococcus (GBS) is a major cause of several infectious diseases in humans and fish. This study was conducted to compare human and fish-derived GBS in terms of their antimicrobial susceptibility, serotype, virulence and pili genes and sequence type (ST), and to determine whether there is a potential linkage of zoonotic transmission in Malaysia. GBS isolated from humans and fish had similar phenotypic characteristics and differed in virulence gene profile, antimicrobial susceptibility, serotype and sequence type. Fish GBS isolates had lower genetic diversity and higher antibiotic susceptibility than human isolates. We report a rare detection of the potentially fish-adapted ST283 in human GBS isolates. Both human and fish ST283 shared several phenotypic and genotypic features, including virulence and pilus genes and antimicrobial susceptibility, illustrating the value of monitoring GBS within the One Health scope. In this study, two human GBS ST283 isolates belonging to the variant common in fish hosts were identified, raising awareness of the zoonotic potential between the different species in Malaysia.

Streptococcus agalactiae Sequence Type 283 in Farmed Fish, Brazil

In 2016 and 2017, we characterized outbreaks caused by Streptococcus agalactiae serotype III sequence type (ST) 283 in Nile tilapia farms in Brazil. Whole-genome multilocus sequence typing clustered the fish isolates together with the zoonotic ST283 and other STs related to cases in humans, frogs, dogs, cattle, and dolphins.