Assessment of the Safety, Growth, and Gut Microbiota Modulation of Neonates Consuming Infant Formula with Bifidobacterium animalis ssp. lactis CP-9 or Lactobacillus salivarius AP-32: Insights from a Four-Month Clinical Study in Newborn Infants Under Two Months Old

Abstract

Abstract Background Breast milk is a natural treasure for newborns, and its microbiota contains a rich array of bacterial species. When breastfeeding is not possible, infant formula with probiotics can be used as a sole source or as a supplement to breast milk. The aim of this study was to investigate the safety, tolerance, growth, and gut microbiota modulation resulting from the consumption of an infant formula with Bifidobacterium animalis ssp. lactis CP-9 (B. animalis CP-9) or Lactobacillus salivarius AP-32 (L. salivarius AP-32), which were isolated from breast milk and the healthy human gut of newborn infants. Methods One hundred and fifty-nine healthy infants were enrolled in this study and separated into three groups: the control group, L. salivarius AP-32 group, and B. animalis CP-9 group. The clinical study evaluated adverse events, growth effects, the incidence of allergies, and gastrointestinal disorders in infants consuming infant formula containing B. animalis CP-9 or L. salivarius AP-32. Finally, the impact of the probiotic infant formula on the gut microbiota was elucidated by next-generation sequencing (NGS) analysis. Results A 4-month intervention revealed that body weight, recumbent length, and head circumference were similar among the three groups. No adverse events related to the intervention were observed. The microbiota composition was more diverse on day 0 and became more uniform by month 4. B. animalis CP-9 and L. salivarius AP-32 were found to be antibiotic susceptible and displayed a low risk of horizontal antibiotic gene transfer. Conclusions The use of B. animalis CP-9 and L. salivarius AP-32 in infant formula was considered safe and well tolerated. Trial registration The trial was registered in the US Library of Medicine (clinicaltrials.gov) with the number NCT03993301 on 20/06/2019.