# Evaluation of a novel liquid-solid biphasic differential medium for screening of group B streptococcus in perinatal women

## TL;DR

A new liquid-solid biphasic medium was tested for detecting group B streptococcus in pregnant women, showing high accuracy and speed.

## Contribution

This is the first study in China to evaluate a biphasic medium for GBS detection in peripartum women.

## Key findings

- L-S StrepB detected 87.3% of GBS cases within 15–24 hours.
- The medium showed 96.9% sensitivity and 100% specificity for GBS detection.
- L-S StrepB is cost-effective and suitable for primary healthcare settings.

## Abstract

This study explored the capabilities of the commonly used blood agar plate in Chinese clinical microbiology laboratories and a novel liquid-solid biphasic differential medium (L-S StrepB) for detecting group B streptococcus (GBS) in peripartum women in China. A total of 11.2% (65/582) of pregnant women at 35–37 weeks of gestation were found to carry GBS. The sensitivity and specificity of L-S StrepB were 96.9% and 100%, respectively. Additionally, 87.3% (55/63) of GBS cases were detected within 15–24 h using L-S StrepB, demonstrating rapid processing time. This method is user-friendly, cost-effective, and requires no specialized equipment, making it suitable for use in primary healthcare settings.

The clinical application methods for group B streptococcus (GBS) detection among peripartum women in medical institutions in China are influenced by various factors, such as cost and personnel availability, leading to a lack of standardization. In this study, we evaluated a novel liquid-solid biphasic differential medium (L-S StrepB) that integrates liquid enrichment with solid agar for the detection of GBS. This is the first reported study in China to utilize biphasic medium for GBS detection. L-S StrepB demonstrates good sensitivity and specificity, with simple operations and low costs, while adhering to guidelines recommending initial enrichment followed by culturing.