Group B Streptococcus colonization in pregnant women and vertical transmission to neonates in Crete Greece: Incidence and risk factors.

BACKGROUND

Group B Streptococcus (GBS) infection remains a significant cause of neonatal morbidity and mortality worldwide. Universal screening using rectovaginal swabs and intrapartum antibiotic prophylaxis for GBS-positive women is a standard practice to prevent early-onset neonatal disease. Colonization rates vary internationally, and comprehensive data from Greece are limited. This study aimed to evaluate the incidence of GBS colonization and associated risk factors among pregnant women in Crete, Greece.

METHODS

This retrospective study included all pregnant women and their newborns admitted to two major hospitals in Crete between January 1, 2015, and December 31, 2019. GBS colonization was assessed via vaginal cultures. Data on maternal age, nationality, area of residence, multiparity, comorbidities (e.g., diabetes, hypertension), number of prenatal visits, gestational age at screening, and mode of delivery were analyzed. Rates of antibiotic prophylaxis and incidence of neonatal GBS disease were also reviewed.

RESULTS

Out of 7362 pregnant women reviewed, 4984 (67.7 %) underwent GBS screening. GBS colonization was found in 83 women (1.7 %). The highest colonization rate was among women aged 31-35 years (34.9 %). Screening before the 35th gestational week occurred in 45.8 % of cases, and comorbidities such as diabetes or hypertension were present in 9.6 %. Multiparity (≥2 births) was significantly associated with colonization (66.3 %), while other factors showed no significant association. All identified GBS-positive women received intrapartum antibiotic prophylaxis, and no cases of neonatal GBS disease were observed.

CONCLUSIONS

The GBS colonization rate in Crete is among the lowest globally reported. Universal screening combined with intrapartum antibiotic prophylaxis effectively prevented neonatal GBS disease. The establishment of clear national guidelines is crucial to ensure consistent screening practices and responsible antibiotic stewardship.