Rifamycin use and gut microbial antibiotic resistance genes in cirrhosis: Results from a double-blind, placebo-controlled clinical trial.

In 30 seconds

This double-blind, placebo-controlled randomized trial assessed changes in gut antimicrobial resistance genes (ARGs) with rifamycin SV MMX (RiVM) in patients with compensated cirrhosis. Thirty participants (15 per group) underwent shotgun metagenomic sequencing before and after 30 days of treatment. RiVM was not associated with significant ARG enrichment compared with placebo after false-discovery-rate adjustment, and the authors reported no increase in infections or treatment-related safety concerns. Analyses suggested a trend toward lower vancomycin-resistance ARGs after RiVM, while some efflux-regulator increases were nominal and did not withstand adjustment.

Key findings

• After 30 days, RiVM did not significantly enrich gut ARGs versus placebo after false-discovery-rate adjustment.
• Analyses showed a trend toward lower vancomycin-resistance ARGs, including vanW and vanT operon-associated genes, after RiVM exposure.
• Several Enterobacteriaceae-associated efflux regulators increased nominally after rifamycin, but these changes did not withstand false-discovery-rate adjustment.
• No increase in infections or treatment-related safety concerns was observed.

Why it matters

Antibiotic resistance gene carriage is associated with poor outcomes in cirrhosis, making the resistome effects of antibiotic exposure clinically relevant. In this small randomized trial, short-term RiVM treatment did not show significant ARG enrichment compared with placebo. The findings offer preliminary evidence about gut resistance patterns but do not establish longer-term effects or resolve the significance of the observed trends.

What to keep in mind

The trial was small and assessed resistome changes only before and after 30 days of therapy; the reported ARG trends were not significant after false-discovery-rate adjustment.