Molecular Epidemiology of Group B Streptococci in Lithuania Identifies Multi-Drug Resistant Clones and Sporadic ST1 Serotypes Ia and Ib

Abstract

Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of neonatal infections. Yet, detailed assessment of the genotypic and phenotypic factors associated with GBS carriage, mother-to-baby transmission, and GBS infection in neonates and adults is lacking. Understanding the distribution of GBS genotypes, including the predominance of different serotypes, antimicrobial resistance (AMR) genes, and virulence factors, is likely to help to prevent GBS diseases, as well as inform estimates of the efficacy of future GBS vaccines. To this end, we set out to characterise GBS isolates collected from pregnant and non-pregnant women in Kaunas region in Lithuania. Whole genome sequences of 42 GBS isolates were analysed to determine multi-locus sequence typing (MLST), the presence of acquired AMR and surface protein genes, and the phylogenetic relatedness of isolates. We identified serotypes Ia (42.9%, 18/42), III (33.3%, 14/42), V (21.4%, 9/42), and a single isolate of serotype Ib. Genomic analyses revealed high diversity among isolates, with 18 sequence types (STs) identified, including three novel STs. 85.7% (36/42) of isolates carried at least one AMR gene: tetM or tetO (35/42), ermB or lsaC (8/42) and ant6-Ia and aph3-III (2/42). This study represents the first genomic analysis of GBS isolated from women in Lithuania and contributes to an improved understanding of the global spread of GBS genotypes and phenotypes, laying the foundations for future GBS surveillance in Lithuania.

Genomic insights into the diversity, virulence, and antimicrobial resistance of group B Streptococcus clinical isolates from Saudi Arabia

“…Of these, CC1 (33.71%, n = 30/89) and CC19 (25.84%, n = 23/89) were the most prevalent, followed to a lesser extent by the hypervirulent CC17 (11.24%, n = 10/89). Overall, the population structure of GBS isolates in this study correlates with previously published data reporting the same dominant CCs among colonizing and infecting isolates ( Bianchi-Jassir et al., 2020 ; McGee et al., 2021 ; Rodgus et al., 2022 ). Nevertheless, the study showed that these main GBS lineages displayed varying levels of intra-lineage serotype diversity.…”

“…Of particular concern was the high proportion of isolates with reduced susceptibility to macrolides and lincosamides, which are the antibiotics of choice for the treatment of GBS infections in patients with penicillin allergies. Here also, the molecular mechanisms of resistance to these antibiotics were consistent with those previously described for this species ( Bergal et al., 2015 ; Jin et al., 2022 ; Rodgus et al., 2022 ; Khan et al., 2023 ). Phylogenetic analysis showed that resistance to macrolides and lincosamides was not necessarily linked to the expansion of certain CCs but was distributed across all detected CCs.…”

“…The lowest diversity was observed among CC17 isolates (n = 10), which mainly belonged to ST17 (n = 9/10) and expressed serotype III-2 ( Figure 1 ). Overall, the phylogeny of the studied collection did not show any evidence of recent serotype switching events, such as the previously described switch from serotype III to IV in CC17 or switch from serotype III to IV in CC17 or from serotype V to Ib within CC1 lineages ( Lopes et al., 2018 ; McGee et al., 2021 ; Rodgus et al., 2022 ).…”

“…Sequenced isolates revealed 28 different STs; however, the majority of the detected STs belonged to four dominant human-associated lineages, including CC1, CC10/12, CC17, CC19, and the more recently described CC452, accounting together for 85.39% (n = 76/89) of all sequenced isolates ( McGee et al., 2021 ; Rodgus et al., 2022 ). Of these, CC1 (33.71%, n = 30/89) and CC19 (25.84%, n = 23/89) were the most prevalent, followed to a lesser extent by the hypervirulent CC17 (11.24%, n = 10/89).…”

“…This might explain the high rate of resistance to these antibiotics in the species that is likely to impact their use for the prevention and treatment of GBS infections. Isolates showing the cMLS B phenotype were distributed across all major CCs and carried the methyltransferase-encoding gene erm(B) , while the isolates exhibiting the iMLS B phenotype belonged to CC1 and CC19 and carried the erm(A) gene ( Lopes et al., 2018 ; Martins et al., 2022 ; Rodgus et al., 2022 ; Khan et al., 2023 ). The few isolates showing the L phenotype coherently harbored the lsa(C) gene and belonged exclusively to CC19 expressing serotype III-1.…”