The prevalence and risk factors of group B streptococcus colonization in Iranian pregnant women

Group B Streptococcus (GBS) is a leading cause of serious neonatal infections. Although great progress has been made in preventing prenatal GBS, its colonization rate in different regions of Iran remains unknown.

To determine GBS colonization prevalence and its risk factors among Iranian pregnant women.

This prospective cross-sectional study was performed on 186 pregnant women, who attended Boo-Ali hospital which is affiliated with Islamic Azad University in Tehran, Iran, from March 2014 to June 2015. The demographic, obstetric and gynecological data were gathered. A recto-vaginal culture was taken from each patient, with a sterile swab, in lithotomy position without using speculum, and vaginal pH was measured. Patients with positive GBS received IV antibiotic therapy during labor (penicillin G 3 gram at first dose then 1.5 gram Q/4h until delivery). Data were analyzed by statistical software SPSS version 21. Statistical tests for differences were performed by Chi-square test. Potential confounding was assessed by logistic regression. Level of significance was set at p<0.05.

Twenty-two (11.8%) patients had positive recto-vaginal colonization. No significant differences between colonized and GBS-negative women with regard to age, obstetrics history and socio-economic factor were noticed. In contrast, smoking, history of previous infection with HPV, presence of vulvitis and a vaginal pH>4.5 were associated with GBS colonization (p≤0.05).

With a relatively low prevalence and few significantly correlated factors, it is hardly possible to define a high risk group of pregnant women for GBS colonization. Therefore, thorough measures should be taken in order to prevent infection complications in mothers and neonates in the Iranian population.