Vaginal Colonization by Streptococcus agalactiae Among Pregnant Women in Jordan: Antimicrobial Resistance, Virulence Genes, and Biofilm Formation

Background: Streptococcus agalactiae is a major cause of neonatal sepsis. This research aims to determine the prevalence of vaginal colonization by Streptococcus agalactiae among pregnant women attending antenatal care at a tertiary hospital in Irbid, Jordan, and to characterize the antimicrobial resistance patterns, biofilm-forming capacity, and virulence and resistance gene profiles of the isolates. Methods: A total of 346 pregnant women were included in the study. The antibiotic susceptibility of the isolates was determined using the Kirby–Bauer method. The ability to produce biofilms was evaluated qualitatively using the Congo red agar method and quantitatively using the tissue culture plate biofilm formation assay. PCR was used to screen the isolates for specific virulence ( scpB, lmb ) and antimicrobial resistance genes ( ermB, ermTR, mefA, mefE , and linB ). Results: Thirty-nine pregnant women (11.3%) tested positive for S. agalactiae . The highest rate of antibiotic resistance was against tetracycline (87.2%), followed by erythromycin (33.3%), and then ofloxacin and levofloxacin (12.8% each). All isolates were susceptible (100%) to ampicillin, meropenem, vancomycin, cefotaxime, rifampin, and cefepime. All isolates demonstrated biofilm production. ScpB and lmb were present in 92.3% and 97.4% of the isolates, respectively. ScpB was significantly associated with lmb . Resistance genes were identified at the following rates: ermB, ermTR , and mefE at 15.4% each, mefA at 10.3%, and linB at 5.1%. The linB and the mefE genes were significantly associated with nonsusceptibility to erythromycin, whereas the mefA gene was significantly associated with susceptibility to tetracycline (P< 0.01). Conclusion: The prevalence of S. agalactiae among pregnant women was relatively low. However, the ScpB and lmb virulence genes were frequently present among the isolates. In addition, all S. agalactiae were biofilm formers. Therefore, the implementation of rigorous, standardized, and timely intervention to manage S. agalactiae in women who test positive is vital to reduce vertical transmission of this pathogen to newborns. Keywords: Streptococcus agalactiae , asymptomatic vaginal colonization, biofilms, virulence genes