Molecular Epidemiology and Antimicrobial Resistance of Group B Streptococcus in Hainan, China: Genomic Insights from Perinatal and Adult Clinical Isolates

Hui-Min Zhao; Xiao-Ding Song; Juan Li; Bei-Bei Miao; Jing-Yi Zhang; Xin-Yi Gong; Yuan He; Ying-Juan Wang; Yong-Shuai Fu; Hua Wu

doi:10.2147/IDR.S617393

Molecular Epidemiology and Antimicrobial Resistance of Group B Streptococcus in Hainan, China: Genomic Insights from Perinatal and Adult Clinical Isolates

Infect Drug Resist. 2026 Jul 15:19:617393. doi: 10.2147/IDR.S617393. eCollection 2026.

Authors

Hui-Min Zhao^#^{1

2}, Xiao-Ding Song^#³, Juan Li⁴, Bei-Bei Miao⁴, Jing-Yi Zhang⁴, Xin-Yi Gong⁴, Yuan He⁵, Ying-Juan Wang⁵, Yong-Shuai Fu⁶, Hua Wu¹

Affiliations

¹ Department of Clinical Laboratory, Hainan Women and Children's Medical Center (Hainan Medical University), Haikou, Hainan, 570206, People's Republic of China.
² Hainan Medical University, Haikou, Hainan, 571199, People's Republic of China.
³ Department of Clinical Laboratory, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Hainan, Haikou, 570311, People's Republic of China.
⁴ National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Haikou, Hainan, People's Republic of China.
⁵ NHC Key Laboratory of Tropical Disease Control, School of Life Sciences and Medical Technology, Hainan Medical University, Haikou, Hainan, 571199, People's Republic of China.
⁶ Changsha Medical University, Changsha, Hunan, 410219, People's Republic of China.

^# Contributed equally.

Abstract

Background: Group B Streptococcus (GBS) is a major cause of perinatal infection and increasingly affects non-pregnant adults. However, comprehensive whole-genome sequencing (WGS)-based molecular epidemiological data from Hainan Province remain largely uncharacterized. The objective of this study was to determine the molecular epidemiology and antimicrobial resistance profiles of GBS, alongside their clinical features, in a hospital in Hainan, China.

Methods: A retrospective analysis was conducted on patients with GBS isolated from clinical specimens at Hainan General Hospital between June 2020 and September 2023. Antimicrobial susceptibility testing was performed using the Vitek 2 Compact system. Capsular serotyping and multilocus sequence typing (MLST) were conducted via whole-genome sequencing.

Results: Among 95 patients with GBS isolated from clinical specimens, 62 (65.3%) were perinatal cases, including 10 confirmed neonatal infections. GBS was isolated from fetal appendageal tissues (placenta, amniotic fluid, and umbilical cord) in 57 perinatal cases. The remaining 33 were non-pregnant adults (mean age 51.8 years), of whom 84.8% had underlying diseases, and urinary tract infection was the most common diagnosis (75.8%). The predominant serotypes were III (36.8%), V (30.5%), and Ib (10.5%). The main sequence types included ST529 (15.8%), ST862 (15.8%), ST1 (13.7%), and ST19 (11.6%). All isolates were susceptible to penicillin and ampicillin, whereas resistance to tetracycline was 96.8%.

Conclusion: This single-center retrospective study provides the first WGS-based molecular epidemiological data from Hainan. GBS infections in Hainan predominantly affect perinatal women and non-pregnant adults with comorbidities. Serotypes III, V, and Ib are the most prevalent. Penicillins retain excellent activity and remain the first-line treatment, whereas tetracycline is not recommended due to near-ubiquitous resistance.

Keywords: antimicrobial resistance; capsular serotyping; epidemiology; group b streptococcus; multilocus sequence typing.