Molecular epidemiology of Group B Streptococcus Isolates from Pregnant Women with Premature Rupture of Membranes in Fuzhou, China

Abstract

Abstract Background Group B Streptococcus (GBS) colonization in late pregnancy is associated with premature rupture of membranes (PROM) and preterm delivery, and may lead to ascending infection and neonatal early-onset disease. This study aims to determine the prevalence, antimicrobial susceptibility, serotypes, and molecular characterization of GBS strains in Fuzhou region of China. Methods A total of 140 GBS isolates were obtained from pregnant women with PROM. All isolates were genotyped, serotyped and tested for drug-resistance and virulence genes using PCR and DNA sequencing. In addition, antibiotic susceptibility testing was performed using Vitek® 2 automated system. Results Among the 140 GBS isolates, seventeen sequence types (STs) were identified, among which ST19 (20.0%) was the most prevalent, followed by ST862, ST10 and ST12. Three clonal complexes (CCs) were identified, namely, CC19, CC10 and CC1. The predominant serotype was III (45.7%), followed by V (23.6%), Ib (18.6%), Ia (7.1%), and II (3.6%). The prevalence of multidrug resistance was 72.8% (102/140). All isolates were susceptible to penicillin G, ampicillin, quinupristin, linezolid, vancomycin, and tigecycline. The majority of isolates were resistant to clindamycin (72.1%), erythromycin (70.0%), and tetracycline (80.7%), and 28.6% of isolates were resistant to levofloxacin and moxifloxacin. Of the 98 erythromycin-resistant strains, mreA was detected in 100% (98/98), followed by ermB (70%, 69/98), mefA (49%, 48/98), mefE (22%, 22/98), ermA (13%, 13/98) and ermTR (9%, 9/98). No linB were detected among 101 clindamycin-resistant strains. Of the 114 tetracycline-resistant strains, tetM, tetK, tetL and tetO was detected in 52.6%, 61.4%, 7.9%, and 23.7%, respectively. For virulence genes detection, all strains carried rib and hylB, followed by bca (98.6%), and scpB (80.7%), whereas only one strain carried bac. Conclusion ST19/III and ST862/III were the most prevalent GBS subtypes. Penicillin G remains a first-line antibiotic for IAP and treatment of GBS infections. Three agents (clindamycin, erythromycin, and tetracycline) should not be used as candidate alternatives for penicillin allergies in this region. Long-term, high-quality surveillance should be conducted to provide a foundation for GBS prevention strategies and vaccine development.