Increase of test accuracy of group B Streptococcus test using a recombinant endolysin.

Streptococcus agalactiae, alternatively called group B Streptococcus (GBS), is vertically transmitted to the newborns during delivery, and can cause fatal neonatal infections including sepsis and pneumonia and (rarely) meningitis. In the late stage of pregnancy, the GBS test is performed to examine the risks of birth canal infection. In the case of a positive test result, the GBS carrier is prophylactically treated with antibiotics to reduce the risks of birth canal infection. An enrichment culture and prior to bacterial identification test are strongly recommended in the GBS test, since the enrichment improves GBS detection greatly. In the GBS test, after a vaginal-and-anorectal swab is inoculated in a GBS enrichment culture, the enriched culture was subjected to the bacterial identification test, such as culture-based method and nucleic acid amplification test. In some cases, the enrichment cultures, the growth of Enterococcus faecalis antagonistically makes GBS growth inhibited in the enrichment culture, and results in negative results in the following identification test. To solve this unwanted result of GBS culture test, the E. faecalis growth is required to be controlled in the enrichment culture. In this study, we originally isolated endolysin EG-LYS and examined the application of a single endolysin to improve the issue of false-negative results in the GBS test. Through the study, we examined the microbiota of vaginal-and-anorectal swab, and the enriched cultures treated with PBS and endolysin EG-LYS.