The Prevalence of Group B streptococcus Rectovaginal Colonization and Antimicrobial Susceptibility Pattern Among Pregnant Women: A Descriptive-Analytical Study

Neonatal infections are significantly correlated with maternal rectovaginal colonization with group B streptococcus during pregnancy. Therefore, screening programs are needed for identifying and treating group B streptococcus colonization among pregnant women. The present study was conducted to assess the prevalence of group B streptococcus rectovaginal colonization and antimicrobial susceptibility pattern among pregnant women.
This descriptive-analytical study was conducted from June 2013 to June 2014 in 500 pregnant women admitted to the maternity unit of Valiasr hospital, Birjand, Iran. Rectovaginal samples were transported in Todd Hewitt broth to a university laboratory. The samples were cultured in blood agar medium and colonial growths in the medium were tested for chemical characteristics of group B streptococcus. Antimicrobial susceptibility was tested via the agar disc diffusion method using Mueller-Hinton culture medium containing 5% - 10% sheep blood. The data were analyzed using SPSS software (v. 18.0) by running the Chi-square and Fisher exact tests at a significance level of less than 0.05.
The study findings revealed that the prevalence of group B streptococcus rectovaginal colonization was 5.2% (26 cases). The highest antimicrobial susceptibility of group B streptococcus was observed to ampicillin (92.2%), trimethoprim-sulfamethoxazole (88.5%), and penicillin G (88.5%), in sequence. Group B streptococcus rectovaginal colonization had significant relationships with age, number of parities, educational status, intrauterine contraceptive device use, history of drug abuse, history of vaginal or urinary tract infections, history of intrauterine fetal death, and history of neonatal death.
The prevalence of group B streptococcus rectovaginal colonization among pregnant women is 5.2%. Given the risks of infections for both women and their neonates, antibiotic therapy is needed to prevent and manage group B streptococcus colonization among pregnant women, particularly during delivery.