Effects of probiotics on enteric flora and feeding tolerance in preterm infants

Background: Probiotics are live microbes that colonize the gastrointestinal tract and benefit the host. Preterm infants develop abnormal patterns of bowel colonization, and only a few clinical trials have reported the outcomes of preterm infants treated with probiotics. Purpose: We investigated the rate of colonization of Lactobacillus and the clinical variables affecting the colonization in preterm infants. Methods: Infants with gestational age less than 37 weeks treated at Ewha Womans University Hospital between March 2003 and July 2004 were eligible. Lactobacillus acidophilus (containing 10⁸ CFU) was supplemented orally, mixed with breast milk or formula divided into three doses a day. Stool samples were collected before and 14 days after supplementation of the probiotic. Stool samples were anaerobically cultured on Rogosa agar and identified by Gram stain, catalase test and glucose fermentation test. Clinical characteristics were analyzed. Results: Seventy-three patients with an average gestational age of 33.0 ± 2.5 weeks were studied. Meconium was cultured in 46 patients and Lactobacillus was not detected. Probiotic supplementation began on 3.4 ± 6.8 days, and after 14 days of supplementation, Lactobacillus was cultured in an average of 3.01 × 10⁸ CFU in the stool of 37.0% (27/73) of the patients. There was a tendency towards an increased incidence of sepsis in the Lactobacillus- group (p = 0.082). In the Lactobacillus+ group, a striking increase in feeding tolerance was detected. Conclusion: In preterm infants, with the administration of probiotics, 37% of the preterm infants had Lactobacillus colonized in the gastrointestinal tract and improved feeding tolerance. A double-blind study is in progress for further investigation into the effect on other systemic diseases in premature infants.