Changes of intestinal microbiota composition and diversity in very low birth weight infants related to strategies of NEC prophylaxis: protocol for an observational multicentre pilot study.

Background: At the Division of Neonatology, Department of Paediatrics, Medical University Graz, a unique regimen of necrotizing enterocolitis (NEC) prophylaxis in preterm infants showing a < 1500 g birth weight (i.e. very low birth weight, VLBW) is used. The regimen includes oral antibiotic and antifungal therapy and probiotic preparations as well as a standardised feeding regimen. The incidence of NEC in preterm infants treated by this regimen has been shown to be lower, reflecting 0.7% when treatment was initiated on the first day of life, compared to international incidence rates (5.1%). However, the impact of the prophylaxis regimen on the intestinal microbiome is yet unknown.

Methods: We here report the protocol of an observational multicentre STROBE compliant pilot study in VLBW preterm infants. Research will compare three groups as defined by different NEC prophylaxis regimens. Each centre will provide 20 infants. Stool samples will be collected every 2 days throughout the first 2 weeks of life. Samples will be stored at - 80 °C until 16S-rRNA sequencing. 16S-rRNA genes will be amplified using suitable primers (specific for bacteria, fungi and archaea) and prepared for MiSeq Sequencing. Analyses will be performed using public analysis-pipelines, such as Mothur and Qiime, thus allowing an analysis of high-throughput community sequencing data. Abundance and composition changes in intestinal microbiota will be compared between the groups throughout the first 2 weeks of life.

Discussion: Different surroundings at the three participating study centres, including contacts to care takers and parents, as well as feeding or medication all might influence intestinal microbiota composition and abundance. In the planned sequel study, this should be kept in mind and a more standardised process ought to be established. However, the results obtained from the presented pilot study will display the burden of bias and help to establish a more strict protocol for the future.

Trial registration: Trial has been registered with the German Registry for Clinical Trials (registry ID DRKS00009290).