Evaluation of a multiplex PCR-based reverse line blot-hybridization assay for identification of serotype and surface protein antigens of Streptococcus agalactiae

Abstract

A 33-primer multiplex PCR-based reverse line blot (mPCR/RLB) assay was developed to identify Streptococcus agalactiae serotypes and surface protein antigen genes simultaneously. It was evaluated by using 551 clinical isolates. The mPCR/RLB assay was more sensitive than conventional serotyping, especially for protein antigen typing, but otherwise the results correlated well.

FIG. 1.

Results of mPCR/RLB assay for 40 consecutive isolates. Sample 35 was buffer, which was used as a negative control. Probes sag59Sp and sag190Ap are group B streptococcus specific. Molecular serotype probes are named according to the corresponding serotype, the cps gene target (e.g., cpsH, cpsK, etc.), and whether the probe is sense (S) or antisense (A). Protein gene probes are named for the corresponding protein, except for GBS1716Ap and GBS1716Sp, which are the sense (S) and antisense (A) probes targeting the Cβ gene (bac) (3, 4).