Effect of probiotics and synbiotics on antimicrobial resistance in frequent infections; a systematic review of clinical trials ´

Background: Antibiotic resistance and recurrent infections, driven by increased antibiotic use, represent a global health problem. This study aims to evaluate the effect of probiotics and synbiotics consumption on antibiotic resistance in common infections. Methods: A systematic search was performed on international electronic databases (PubMed/Medline, Scopus and Web of Science) using predefined keywords to identify relevant clinical trials published prior to 1 March 2025. Study quality was assessed, and the PRISMA 2020 guideline was followed. Results: In our systematic review, 47 studies included. Twenty studies reported positive effects on antibiotic resistance, eradication rates, and recurrence, particularly in gastrointestinal infections. In contrast, ten studies reported no effect, and two indicated a negative effect of these interventions on infection recurrence and antibiotic resistance. In three studies focusing on children, probiotics significantly lowered the risk of urinary tract infection (UTI) recurrence and antibiotic resistance. However, an adult study found that probiotics had minimal effect on UTI recurrence. Four studies examined the effect of probiotics on respiratory infections in both children and adults, showed improvements in antibiotic resistance outcomes. Three studies involving preterm infants found that probiotics could modify their gut microbiome composition, with two studies confirming this effect. Conclusion: Our study indicates that incorporating probiotics and synbiotics into common infection therapy could improve antibiotic resistance, eradication rates, minimize side effects, and boost treatment compliance. However, concerns remain regarding the potential transfer of antibiotic resistance genes via probiotics.