Determination of group B streptococcal genes encoding putative adherence factors in GBS clinical strains

Group B streptococcus (GBS) is part of the vaginal flora of many women and is an important cause of invasive bacterial disease in newborns. In spite of extensive research on this organism in recent years, little is known about the specific virulence factors responsible for increased bacterial pathogenicity. The goal of the present work was to assess the presence of putative adherence genes, located on GBS pathogenicity islands in various regions of the genome, in a group of clinical isolates. The putative adherence genes, originally found by subtractive hybridization and designated as sspB1 and sspB2, encoded proteins homologous to the broad family of adherence and aggregation proteins commonly found in Gram-positive bacteria. The clinical GBS strains consisted of 118 isolates were analyzed for the presence of sspB1 and sspB2 employing PCR and DNA hybridization. The occurrence of the genes under study in the genome correlated with severity of the case; for example, sspB1 and sspB2 variants were most common for invasive GBS strains and strains isolated from urine. There was no correlation between the presence of the sspB genes in the genome and specific serotype.