Gut microbiota in preterm infants with gross blood in stools: A prospective, controlled study

Objective: Gross blood in stools is a peculiar entity in preterm infants, but little is known about its etiology. As gut microbiota can be distorted in preterm infants, we aimed to evaluate the gut microbiota in infants with gross blood in stools. Study design: In a prospective, controlled, single-center study, we enrolled all infants born before 34 weeks of gestational age presenting gross blood in stools that was either completely isolated or associated with mild clinical symptoms or radiological signs. Each case was paired with two controls who were hospitalized in the same unit and were matched for gestational age and birth weight. The diversity of the gut microbiota was analyzed using 16S rRNA gene PCR and temporal temperature gel electrophoresis. We calculated a diversity score corresponding to the number of operational taxonomic units present in the microbiota. Results: Thirty-three preterm infants with gross blood in stools were matched with 57 controls. Clinical characteristics were similar in cases and controls. There was no statistically significant difference in the diversity score between the two groups, but microbiota composition differed. The proportion of infants with Escherichia coli was significantly higher in cases than in controls (p = 0.045) and the opposite pattern occurred for Staphylococcus sp. (p = 0.047). Conclusion: Dysbiosis could be a risk factor for gross blood in stools in preterm infants. Additional, larger studies are needed to confirm the implications of the presence of different genotypes of E. coli and to evaluate preventive actions such as the prophylactic use of probiotics and/or prebiotics. (C) 2014 Elsevier Ireland Ltd. All rights reserved.