Bifidobacterium longum subsp. infantis BI45 demonstrates excellent safety across genomic, preclinical, and human RCT assessments

The increasing consumption of probiotics for various health benefits necessitates rigorous safety evaluations, especially for novel strains. While many probiotics are generally recognized as safe, concerns persist regarding potential antibiotic resistance gene transfer, virulence factors, or adverse effects in susceptible populations. Current regulatory frameworks often require comprehensive assessments beyond basic in vitro tests. This study addresses the critical gap by providing a holistic safety profile for Bifidobacterium longum subsp. infantis BI45, covering genomic, preclinical, and clinical trial data to ensure its suitability for human consumption.

Researchers conducted a multi-faceted safety assessment of Bifidobacterium longum subsp. infantis BI45. Initial steps involved whole-genome sequencing to screen for antibiotic resistance and virulence genes, followed by in vitro phenotyping for hemolysis, cytotoxicity, gastrointestinal tolerance, and antibiotic susceptibility. An acute oral toxicity study was performed in mice, administering 2 × 10¹⁰ CFU/kg of BI45. Finally, a randomized, double-blind, placebo-controlled clinical trial enrolled 48 healthy adults (n=24/group) who received either B. infantis BI45 or placebo daily for 8 weeks. Primary endpoints included adverse events and changes in hematological, biochemical, and immunological parameters, alongside gut microbiota analysis using 16S rRNA sequencing.

Genomic analysis of B. infantis BI45 confirmed the absence of transferable antibiotic resistance or virulence genes. In vitro assays further supported its safety, showing no hemolytic or cytotoxic activity and high tolerance to gastrointestinal conditions. Antibiotic susceptibility testing demonstrated that B. infantis BI45 is sensitive to a range of common antibiotics. The acute oral toxicity study in mice revealed no adverse effects, even at a high dose of 2 × 10¹⁰ CFU/kg. The subsequent randomized controlled clinical trial in healthy adults provided robust evidence of safety: > No adverse events were observed in the B. infantis BI45 group over the 8-week intervention period, nor were there significant alterations in hematological, hepatic, or renal function markers compared to placebo. This comprehensive assessment collectively established an excellent safety profile for B. infantis BI45.