Anahita Mazandarani - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Zohre Pournia - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Leila Fozouni - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Iman Hosein pour - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Morteza Khademi - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
Mohammad Mahdi Akhoondi - Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran

Background and purpose: Group B Streptococcus is part of normal flora of the gastrointestinal andgenital tracts in women and is the leading cause of septicemia and meningitis in newborns. The aimof this study is to investigate the anti-bacterial effects of Zinc oxide on the growth of drug-resistantstrains of group B Streptococcus isolated from pregnant women .Materials and Methods: This cross-sectional study was conducted on ۱۵۰ pregnant women of ۲۸–۳۷weeks admitted to seven hospitals and maternity wards in Golestan province. For bacterialidentification, rectovaginal swabs were firstly inoculated to the Todd-hewitt Broth and cultured inblood agar (containing ۵% sheep blood) . Then microbiologic tests were performed to detect group BStreptococci. Disk diffusion and broth microdilution tests were used to determine the bacterialsusceptibility to antibiotics. The antibacterial properties of Zinc oxide nanoparticles were evaluatedusing agar well-diffusion method .Results: The prevalence of group B Streptococcus was ۱۸% in pregnant women. ۹۰% and ۴۵% ofisolates were resistant to clindamycin and erythromycin respectively, and susceptibity to cefazolinwas ۷۱%. In addition, susceptibility to ampicillin and penicillin were ۷۴% and ۵۵% respectively, andall of the group B Streptococci resistant to antibiotics were covered at concentrations of ۲۰۰ and ۱۰۰mg/l.Conclusion: Zinc oxide nanoparticle showed high antimicrobial effect and it was revealed that thebactericide effect increases upon the increase in the concentration of the nanoparticle.

Group B beta-hemolytic streptococcus, pregnant women, zinc oxide nanoparticles, drugresistance