Systematic review: effect of probiotics on antibiotic-induced microbiome disruption.

The effectiveness of probiotics in preventing or reversing antibiotic-induced microbiome disruption remains uncertain, and claims of microbiome restoration to its pre-antibiotic state may be overestimated. In this review, we aimed to assess the efficacy of probiotics in preventing or ameliorating disruptions in microbiome composition and function induced by antibiotic treatment. We searched Medline, Embase, and CENTRAL for randomised controlled and non-randomised trials. Participants were individuals of any age who were on systemic antibiotics with a low risk of baseline dysbiosis. The intervention consisted of probiotics during or after antibiotic treatment, compared to placebo, alternative interventions, or no intervention. Outcomes included microbiome composition and diversity analysed using high-throughput molecular methods, alongside microbial function and resistome assessments. Seven studies, reported in eight papers, were reviewed. One study showed probiotics counteracting antibiotic-induced diversity changes, another showed exacerbation of these changes, and four others showed no effect. Effects on taxa abundance ranged from mitigating dysbiosis to selective modulation, no effect, or delayed recovery. One study observed no impact on the resistome, while another reported an increase in antibiotic resistance genes. In conclusion, heterogeneous results preclude a definitive conclusion on the effectiveness of any specific probiotic in restoring antibiotic-exposed microbiomes. For a clearer understanding, future research should be more standardised and long-term, employing advanced methods, such as 16S rRNA gene sequencing and metagenomic sequencing. These studies should strive to include larger, diverse populations to enhance generalisability and clearly define what constitutes a healthy microbiome. Finally, linking changes in the microbiome to specific clinical outcomes is essential for clinical decision making. PROSPERO registration number: CRD42023446214.