Abstract
BACKGROUND: Preterm infants discharged from the neonatal intensive care unit (NICU) have a risk of severe viral respiratory tract infections (RTIs). Researchers have recently reported the potential use of postbiotics to decrease RTIs in young children. However, the safety and efficacy of postbiotics for preventing RTIs in preterm infants is not yet established. METHODS: We conducted a pilot double-blind, randomized, placebo-controlled study of the heat-killed lactic acid bacterium Pediococcus acidilactici K15 in 41 preterm infants born at <36 weeks of gestation and discharged from the NICU at Chiba University Hospital. RESULTS: Following once-daily K15 or placebo treatment for one year, no significant differences were found in the mean number of febrile days (4.5 [1.5-7.4] days vs. 6.6 [2.6-10.5] days). The subgroup analysis showed that the effect of treatment on the number of febrile days was more prominent in the K15 group than in the placebo group, among children with older siblings. The 16S rRNA gene sequencing of fecal samples illustrated that the genus Faecalimonas was enriched in the K15 group, potentially promoting butyrate production by butyrate-producing bacteria. No adverse events were found to be associated with K15 intake. CONCLUSION: There were no clear data to show the effectiveness of K15 in preventing fever and RTIs in preterm babies during infancy. A larger clinical trial is warranted.