Serotype Prevalence of Group B Streptococcus Among Pregnant Women in Iran: A Systematic Review and Meta-Analyses From 2007-2022 Publisher



Banar M ; Emaneini M ; Jabalameli F ; Beigverdi R
Source: International Journal of Fertility and Sterility Published:2026

Abstract

Background: Group B Streptococcus (GBS; Streptococcus agalactiae) is a significant cause of invasive disease in newborns, often stemming from recto-vaginal colonization in pregnant women. The GBS capsular polysaccharide is a major virulence factor, and ten distinct serotypes (Ia, Ib, II–IX) have now been identified. Understanding the prevalence of these serotypes in maternal colonization is crucial for vaccine development. This study aims to determine the serotype prevalence of GBS among Iranian pregnant women. Materials and Methods: A systematic search was conducted in MEDLINE (via PubMed), Embase, Web of Science, and the Iranian Databases (SID and Magiran) for studies published between January 2000 and March 2023. Studies were included if they used standardized methods for GBS detection, including recto-vaginal specimen collection and identification [selective media and molecular detection of GBS-specific gene (dltS and atr)]. Studies using nonstandard methods (e.g., cervical, perianal, perirectal or perineal specimens), or focusing on non-maternal GBS colonization were excluded. Meta-analyses were performed using Comprehensive Meta-Analysis (Biostat V2.2) software to estimate serotype prevalence with 95% confidence intervals (CIs). Results: Of 330 articles identified, 14 studies met the inclusion criteria. The meta-analyses showed that 93.2% (95% CI: 90-95.5) of GBS isolates had identifiable serotypes. The predominant serotype was serotype III [39.6% (95% CI: 31.6-48.2)], followed by serotypes II [16.8% (95% CI: 13.8-20.4)], V [14.1% (95% CI: 11.2-17.6)], VI [12.4 (95% CI: 8.2-18.5)], Ia [11.7% (95 CI: 7.8-17.2)] and Ib [11.2 (95% CI: 6.9-17.6)]. Conclusion: Serotype III is the most common GBS serotype among pregnant women in Iran, followed by serotypes II, V, VI, Ia, and Ib. These findings suggest that a pentavalent vaccine targeting these serotypes could be beneficial for preventing GBS-related complications in Iranian pregnant women. However, further research is needed to evaluate the efficacy and implementation of such a vaccine. © 2026, Royan Institute (ACECR). All rights reserved.