Abstract
Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of sepsis and meningitis in neonates. In Japan, the universal screening for maternal GBS colonization is recommended to decrease neonatal infections. However, the conventional methods cannot fully detect GBS and produce some false negative results. In this study, we evaluated a new GBS enrichment broth, which changes its color in the presence of GBS, in comparison with the conventional direct agar plating. We also evaluated the usefulness of a latex agglutination (LA) test for the broth after 24-h incubation. First, we estimated the efficiency of the enrichment broth using 100 samples. The detection rates of GBS were 13% (13/100) and 18% (18/100) in direct agar plating and enrichment broth culture, respectively. The positive predictive value of GBS in the broth that changed to yellow was 25.7% (18/70), and the negative predictive value in the broth that did not change to yellow was 100% (30/30) after 24-h incubation. All GBS-positive swabs changed the color of the broth to yellow after incubation up to 24-h. The LA test for the cultured broth detected all GBS with no false positive or false negative results when using 246 additional samples. These results show that this new enrichment broth is more sensitive than direct agar plating in the detection of GBS. Furthermore, the LA test for the cultured broth can contribute to the improvement of GBS detection. In conclusion, our study indicates that the new GBS enrichment broth and the LA test are useful as sensitive and specific methods for GBS screening in pregnant women.
