Genotypes and Virulence Genes in Group B Streptococcus Isolated in the Maternity Hospital,Kuwait

Objective

To characterize group B streptococcus (GBS) isolates obtained from patients at the Maternity Hospital in Kuwait for their genotypes and carriage of virulence genes.

Materials and Methods

A total of 154 GBS isolates were obtained from July 1 to October 31, 2007, from vaginal swabs (n = 95), urine (n = 46), blood (n = 4) and miscellaneous sources (n = 9). Genotypes were obtained by pulsed-field gel electrophoresis (PFGE), following digestion with SmaI or EagI restriction enzymes. PCR was used to screen for the carriage of virulence genes including: surface protein of group B streptococcus (spb1), secreted fibrinogen-binding protein (fbsB), C5a peptidase (scpB), laminin-binding protein (lmb), α− (bca) and β-subunits of the C protein (bac), resistance to protease immunity protein (rib), and phage-associated gene (pag); regulatory protein (dltR), and toxins CAMP factor (cfb), hyaluronidase (hylB) and superoxide dismutase (sodA).

Results

PFGE defined 14 genotypes differentiating isolates with the same serotypes into different genetic backgrounds. All isolates contained genes for virulence factors. However, cfb (99.4%), scpB (88.3%), lmb (88.3%), bca (57.8%), sodA (55.8%) and dltR (53.9%) were the common virulence genes. In total, 144 (90.3%) of the isolates contained 3 or more virulence genes. However, while cfb, lmb and scpB occurred in all genotypes, others occurred in some but not in all genotypes.

Conclusions

GBS isolates obtained at the Maternity Hospital, Kuwait, belonged to diverse genetic backgrounds with the majority carrying multiple virulence genes.Key Words: Group B streptococcus, Genotypes, Pulsed-field gel electrophoresis, Virulence genes