Clinical diagnosis of group B streptococci by scpB gene based PCR.

BACKGROUND & OBJECTIVES: The goal of the present study was to improve and simplify the diagnosis of Streptococcus agalactiae (group B Streptococcus, GBS) infection for routine clinical practice.

METHODS

A total of 71 clinical samples were tested by microbiologic culture, counter immunoelectrophoresis (CIE) and PCR described in the literature. Southern hybridization was accomplished with the Enzo(TM) "DNA Labeling and Detection Kit", Roche (Germany). The computer techniques were used for selection of the specific primers and for analysis of the sizes of PCR products.

RESULTS

The primers for the regions around the 51 bp deletion in C5a peptidase gene (scpB) of GBS were selected. PCR analysis revealed the 255 bp amplification fragment in GBS, 306 bp fragment in groups A and G streptococci (GAS, GGS) and did not reveal any fragments in other bacterial species. Among 71 urine and serum clinical samples tested, none were found to be GBS positive by microbiologic culture, 16 samples by CIE, 36 by PCR. The specificity of amplification was confirmed by Southern hybridization.

INTERPRETATION & CONCLUSION: The 51 bp deletion in scpB gene in comparison with scpA and scpG genes can be used as a diagnostic tool for identification of GBS. The 51 bp deletion based PCR proved to be faster and more reliable test than microbiologic culture or CIE.