Colonization of rectovaginal Escherichia coli and group B streptococci in mothers and on infants\' body surface and their related risk factors

Background: Microorganisms that cause early neonatal sepsis are usually already colonized rectovaginal area in mothers. The most common of these organisms is group B streptococci (GBS) and intestinal gram-negative bacteria mostly Escherichia coli (E.coli). The use of prophylactic antibiotics against GBS has increased in recent years. This study aimed to determine the current situation and frequency of E.coli and GBS colonization in mothers and their infant. Methods: All pregnant women with gestational age≥26 weeks, progressive labor pain and no history of using antibiotic were entered into the current study. A sterile cotton swab culturing from distal third of vaginal and rectum of mothers, and six hours after delivery from external ear canal, nose, groin and umbilicus of infant has been taken. All samples were transferred to the laboratory in Stuart’s media, and then cultured to standard media within 24 hours and the main two organisms in neonatal sepsis (E.coli and GBS) were isolated from mothers' and infants' cultures. Results: E.coli and GBS were 56.3% and 11.2% respectively in rectovaginal culture, and 29.8% and 8.8% in infants’ body surface culture. There was a significant difference in rectovaginal GBS colonization between term (13.6%) and preterm (3.2%) (P=0.005), while the frequency of positive E.coli culture was 52.8% in term deliveries and 68.1% in preterm ones, showing a significant difference (P=0.009). Conclusions: Since E.coli is more common in preterm delivery in this geographical region, in cases of amniotic membrane rupture, mothers should be adequately protected with prophylactic antibiotics against neonatal sepsis.