Fecal microflora in healthy infants born by different methods of delivery:Permanent changes in intestinal flora after cesarean delivery

Background: Newborn infants in modern maternity hospitals are subject to nu merous factors that affect normal intestinal colonization-for example, cesa rean delivery and antimicrobial agents. To study the duration of the effect of external factors on intestinal colonization, two groups of infants with different delivery methods were investigated. Methods: The fecal flora of 64 healthy infants was studied prospectively. T hirty-four infants were delivered vaginally, and 30 by cesarean birth with antibiotic prophylaxis administered to their mothers before the delivery. T he fecal flora was cultured on nonselective and selective media in infants 3 to 5, 10, 30, 60, and 180 days of age. Gastrointestinal signs were record ed daily by the mothers for 2 months. Results: The fecal colonization of infants born by cesarean delivery was de layed. Bifidobacterium-like bacteria and Lactobacillus-like bacteria coloni zation rates reached the rates of vaginally delivered infants at 1 month an d 10 days, respectively. Infants born by cesarean delivery were significant ly less often colonized with bacteria of the Bacteroides fragilis group tha n were vaginally delivered infants: At 6 months the rates were 36% and 76%, respectively (p = 0.009). The occurrence of gastrointestinal signs did not differ between the study groups. Conclusions: This study shows for the first time that the primary gut flora in infants born by cesarean delivery may be disturbed for up to 6 months a fter the birth. The clinical relevance of these changes is unknown, and eve n longer follow-up is needed to establish how long-lasting these alteration s of the primary gut flora can be.