Role of probiotic as adjuvant in treating various infections: a systematic review and meta-analysis

Research on the advantages of probiotics has attracted increasing interest based on the number of publications, products, and public awareness of their benefits. This review evaluated the role of probiotics (single and multiple regimens) as an additional regimen to treat common infectious diseases, including Helicobacter. pylori, diarrheal infections, urinary tract infections (UTIs), upper respiratory tract infections (URTIs), and HIV infections.

We searched randomized controlled trials from PubMed, Scopus, Embase, and Cochrane and identified 6,950 studies. Duplicates were removed, and titles and abstracts were filtered. Bias was evaluated using the Cochrane Risk of Bias Tool for Randomized Trials (ROB 1.0 and 2.0). The certainty of the evidence was evaluated using GRADE. Data were extracted and meta-analysis was performed using RevMan.

A total of 32 studies were included in this study (22 H. pylori studies, 2 diarrheal infection studies, 6 UTI studies, and 2 HIV infection studies). There was no study on URTI. Probiotics, in addition to primary treatment, could improve the eradication of H. pylori versus the control (RR: 1.09; 95% CI:1.04 - 1.13, p value = 0.001) and achieve a cure range of Nugent score in UTI patients (RR 1.38; 95% CI: 1.01 - 1.89, p value = 0.04). For eradicating H. pylori infection, subgroup analysis based on the therapy regimen showed that standard triple therapy was slightly superior compared to quadruple therapy in eradicating H. pylori (RR: 1.14 vs. 1.01, respectively). Single strain probiotics showed a similar effect to multiple strain probiotic regimens (both had an RR of 1.09). The effect estimates of the use of single strain probiotics as adjuvant therapy in eradicating H. pylori and the use of probiotics in UTI had a high certainty of evidence. Meta-analysis was not performed for infectious diarrheal because there were only two eligible studies with different probiotic supplementations and outcome parameters. Nonetheless, they showed that the diarrheal incidence was lower and complete remission of diarrheal was higher after the regimen of probiotics. Similarly, a meta-analysis was not performed for HIV infection because the two eligible studies used different designs and comparators with contradicting findings.

This meta-analysis showed beneficial use of single strain probiotics as adjuvant therapy in eradicating H. pylori and the use of probiotics in UTI. Probiotic supplementation might not be beneficial for patients given a quadruple therapy. Single-strain and multi-strain probiotic regimens had similar effects in increasing the eradication rate of H. pylori. Our study also suggested that the benefits of probiotics as an additional regimen in infectious diarrheal and HIV infections remain unclear; more studies are needed to confirm the benefits.