Genomic epidemiology of Streptococcus agalactiae ST283 in Southeast Asia

Abstract

Streptococcus agalactiae, also known as Lancefield Group B Streptococcus (GBS), is typically regarded as a neonatal pathogen; however, several studies have shown that the bacteria are capable of causing invasive diseases in non-pregnant adults as well. The majority of documented cases were from Southeast Asian countries, and the most common genotype found was ST283, which is also known to be able to infect fish. This study sequenced 12 GBS ST283 samples collected from adult patients in Thailand. Together with publicly available sequences, we performed temporo-spatial analysis and estimated population dynamics of the bacteria. Putative drug resistance genes were also identified and characterized, and the drug resistance phenotypes were validated experimentally. The results, together with historical records, draw a detailed picture of the past transmission history of GBS ST283 in Southeast Asia.

Differential Interaction between Invasive Thai Group B Streptococcus Sequence Type 283 and Caco-2 Cells

“…Taken together, the results of this study highlight the potential of intestinal GBS to cause invasive infection in humans. Although whole genome sequences of isolates in our study, such as E19, PK, B117, B105, and E5, were clustered with other Thai ST283 isolates [ 11 ], cell interaction studies using Caco-2 cell monolayers showed that these isolates were phenotypically different in their magnitudes of invasiveness, their capacity for intracellular survival, and their capability to translocate across polarized Caco-2 cell monolayers. These discrepancies between ST283 isolates could be in part due to the differential expression of genes involved in pathogenicity [ 12 ].…”

“…The tendency of this ST to cause invasive disease in patients of various ages, including younger adults, implies that this genotype might have adapted to overcome more potent immune responses of the host. Phylogenetic analysis using whole genome sequences of ST283 recovered from patients of different ages from Southeast Asian countries, including the 12 invasive isolates in this study (see materials and methods), revealed that the genome sequences of isolates from Thailand, Laos, and Singapore are clustered within the same clade [ 11 ], implying that these isolates are genetically closely related.…”

“…One additional isolate, PK, was recovered from the blood of a young, previously healthy adult patient who had septic arthritis in 2018. Among these, 12 isolates; A5, A26, B105, B117, B140, C62, D23, D44, E4, E5, E19, and PK were published [ 11 ]. All isolates were verified by CAMP test and were tested for the presence of the atr gene [ 16 ].…”

“…This ST has also been reported to cause invasive disease in humans and fish across Southeast Asia including Thailand [ 8 ], and its zoonotic potential has been proposed [ 9 , 10 ]. The transmission from fish to humans remains unproven, despite a few reports suggesting a phylogenetic link between GBS isolates from fish and humans [ 9 , 11 ]. The requirements for foodborne transmission include the ability of GBS to colonize intestinal epithelial cells, invade, and translocate across the epithelial barrier to other sites of the body to establish infections [ 12 ].…”

An Application of Real-Time PCR and CDC Protocol May Significantly Reduce the Incidence of Streptococcus agalactiae Infections among Neonates

“…They usually involve real-time PCR, either "in house" assays, dedicated to a number of PCR devices or molecular platforms. All of them differ in sensitivity and specificity of the results [1,[31][32][33][34][35][36][37][38][39][40][41][42][43].…”