Prevalence of serotypes, antibiotic resistance and virulence genes of Group B Streptococcus isolated from pregnant women at 35–37 weeks of gestation in Ho Chi Minh City, Vietnam

Objective: To analyse the prevalence of serotypes, antibiotic resistance, and virulence genes of Group B Streptococcus (GBS) strains isolated from pregnant women at 35-37 weeks of gestation in Ho Chi Minh City, Vietnam, from January 2022 to January 2023. Methods: GBS strains were isolated through selective culture methods and confirmed by PCR. Serotyping, virulence gene detection, and antibiotic susceptibility testing were performed using PCR, gel electrophoresis techniques and Kirby-Bauer test. Results: Totally, 61 GBS isolated from 300 participants have been identified including seven GBS serotypes (Ia, I b, II, III, IV, V, and VI). Serotypes VII, VIII, and IX were not detected in the study population. Antibiotic resistance patterns varied: 13.1% of isolates were fully susceptible, while the majority showed multi-drug resistance, with 34.4% resistant to three antibiotics. Serotype I a demonstrated high susceptibility (35.7%), while serotype III showed extensive resistance, with 87.5% being resistant to at least three antibiotics. All strains are susceptible to vancomycin and β-lactams susceptibility also remained high, but resistance to clindamycin, erythromycin, and tetracycline was high (>65%). The virulence genes scpB, cylB, fbsB , and cfb were highly prevalent (90%-100%), indicating their potential for vaccine and diagnostic development. Conclusions: Our findings provide valuable insights into GBS serotypes, resistance, and virulence factors, contributing to community monitoring, preventive measures, diagnostics, and vaccine development. However, the limited sample size necessitates further research.