Genetic diversity of Streptococcus agalactiae strains and density of vaginal carriage

Abstract

We screened 500 pregnant women who had no risk factors for Streptococcus agalactiae vaginal carriage, and isolated 39 S. agalactiae strains (8 %). The density of carriage was low in 16 cases (41 %), intermediate in 16 cases (41 %) and heavy in seven cases (18 %). Strains were mostly of serotype III (41 %), Ia (26 %) and V (18 %). Thirty-five strains had at least one of five genetic markers that have been associated with virulent phylogenetic subgroups of strains. Using PCR, nine strains (23 %) were identified as belonging to CC17. The 39 vaginal strains that were studied exhibited a substantial genetic diversity; there were 39 PFGE profiles and 13 variants defined on the basis of the five genetic markers studied. The prevalence of the studied genetic characteristics was similar for strains associated with all three classes of density of carriage. These data suggest that genetic features that are markers of S. agalactiae strains able to invade the central nervous system of neonates are not determinants for vaginal adaptation.

Evaluation of a novel real-time PCR test based on the ssrAgene for the identification of group B streptococci in vaginal swabs

“…A relatively low carriage rate obtained by culture for GBS in this study was similar to the carriage rate of 8% reported in a recent study where vaginal swabs from pregnant women were screened for GBS [28]. Ideally, both vaginal and rectal swabs are required to ensure the highest possible GBS detection rate [29].…”

High Prevalence of Fluoroquinolone-Resistant Group B Streptococci among Clinical Isolates in China and Predominance of Sequence Type 19 with Serotype III

“…Serotype III was the most prevalent, accounting for 63.7% of the isolates, followed by serotypes Ia (21.9%), II (9.6%), and V (4.8%). These findings are similar to previous reports from North America and Europe (9,10). Serotype Ia was significantly higher in children than in adults (42.9% versus 23%, respectively; P ϭ 0.0414) ( Table 1).…”

Characterization of Isolates of Streptococcus agalactiae from Diseased Farmed and Wild Marine Fish from the U.S. Gulf Coast, Latin America, and Thailand

“…Genetic diversity among S. agalactiae isolates recovered from humans, bovine, and fish has been previously demonstrated Jafar et al 2008;Olivares-Fuster et al 2008;Suanyuk et al 2008;Pereira et al 2009;van der Mee-Marquet et al 2009;Qasem et al 2010). Evans et al (2008) demonstrated that piscine GBS from Brazil, Israel, Honduras, and the USA appeared to represent a distinct genetic population of strains that were largely unrelated to human GBS or bovine GBS.…”

“…Moreover, S. agalactiae and S. iniae are recognized as zoonotic bacteria-capable of causing diseases and mortality in humans (Weinstein et al 1997;Brodeur et al 2000;Shoemaker et al 2001;Agnew and Barnes 2007;Pombert et al 2009). Streptococcus agalactiae (also referred to as group B streptococcus [GBS]) infects a wide range of species but is commonly associated with diseases in bovine (mastitis) and humans (neonatal meningitis, sepsis, pneumonia, and osteomyelitis; Evans et al 2005;Kawamura et al 2005;Springman et al 2009;van der Mee-Marquet et al 2009) as well as fish and frogs (Wilkinson et al 1973;Amborski et al 1983). Strains from these different hosts exhibit similar whole-cell protein patterns when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that they have a similar ancestry (Elliott et al 1990).…”