Group B Streptococcus in Indian pregnant women: Its prevalence and risk factors

To study the prevalence of group B streptococci (GBS) in Indian pregnant women and associated risk factors.

Four hundred and fifty pregnant women attending antenatal outpatient/inpatient department between 35-38 weeks of gestation were enrolled in the study. All enrolled subjects were assessed by a predefined proforma for their demographics, socio-economic characteristics, education, toilet habits, obstetric history and clinical outcome. Two cotton swabs each from lower vagina and rectum were collected and plated on selective solid media CHROM agar Strept B (CHROMagarTM) and selective Enrichment Broth LIM RambaQUICK StreptB broth (CHROMagarTM). Presumptive identification of GBS was growth of 1-3 mm grayish white β-hemolytic colonies on BAP or mauve coloured colonies on CHROM agar Strept B. All presumptively identified GBS were confirmed as group B streptococcus by automated identification system-Vitek MS (Bio Merieux).

The recto vaginal colonization rate of GBS in this study was observed as 3.3% (n=15). GBS colonization was significantly associated with nulliparous women (p= 0.026) and use of western style toilet (p=0.017). GBS urinary tract infections was also seen more commonly in women with GBS rectovaginal colonization (p=0.002).

Due to the low GBS prevalence and no significant association with major risk factors, we recommend to institute universal screening of GBS in pregnant women, instead of risk based screening. Since this was a single centric study with low prevalence of GBS, its applicability may be limited, therefore further larger multi-centric prospective studies are required to understand the true GBS prevalence in Indian society.