Effect of probiotic strain, duration, and dose on preventing ICU-acquired infection: A scoping review

Background Intensive care unit-acquired infections (ICU-AIs) are prevalent among critically ill patients due to multiple invasive procedures. Probiotics have emerged as a potential preventive strategy to lower infection rates in ICU settings. However, studies assessing probiotic effectiveness have reported inconsistent results, suggesting that these discrepancies are due to variations in probiotic strain, intervention duration, and dosage. Despite the growing interest and the existence of several reviews, the optimal probiotic strain, duration, and dosage for ICU patients remain uncertain. Objectives This review aims to assess the impact of strain specificity, intervention duration, and dosage on the effectiveness of probiotic supplementation in preventing ICU-AIs. Methods This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A comprehensive search was conducted in electronic databases for English-language interventional and observational studies published between January 2014 and August 2024. Eligible studies were those that evaluated the efficacy of probiotics in reducing ICU-AIs. Data were extracted using a standardized form that included details on strain designation, intervention duration, and dosage. Findings were synthesized descriptively using narrative text, tables, and figures. Results Eighteen different probiotic strains were identified. Lactobacillus acidophilus LA-5, particularly in multi-strain formulations, was commonly associated with positive outcomes. Probiotic regimens with intervention durations of 14 days or more and dosages of at least 5 × 10⁹ CFU/day demonstrated greater effectiveness in reducing ICU-AIs. Conclusions Strain-specificity, intervention duration, and dosage are important factors influencing probiotic effectiveness in ICU-AI prevention. Further studies are needed to confirm the efficacy of promising strains and explore the potential of new ones.