Rifamycin SV-MMX® for treatment of travellers' diarrhea: equally effective as ciprofloxacin and not associated with the acquisition of multi-drug resistant bacteria.

Background: The novel oral antibiotic formulation Rifamycin SV-MMX®, with a targeted delivery to the distal small bowel and colon, was superior to placebo in treating travellers' diarrhea (TD) in a previous study. Thus, a study was designed to compare this poorly absorbed antibiotic with the systemic agent ciprofloxacin. Methods: In a randomized double-blind phase 3 study (ERASE), the efficacy and safety of Rifamycin SV-MMX® 400 mg twice daily (RIF-MMX) was compared with ciprofloxacin 500 mg twice daily in the oral treatment of TD. Overall, 835 international visitors to India, Guatemala or Ecuador with acute TD were randomized to receive a 3-day treatment with RIF-MMX (n = 420) or ciprofloxacin (n = 415). Primary endpoint was time to last unformed stool (TLUS), after which clinical cure was declared. Stools samples for microbiological evaluation were collected at the baseline visit and the end of treatment visit. Results: Median TLUS in the RIF-MMX group was 42.8 h versus 36.8 h in the ciprofloxacin group indicating non-inferiority of RIF-MMX to ciprofloxacin (P = 0.0035). Secondary efficacy endpoint results including clinical cure rate, treatment failure rate, requirement of rescue therapy as well as microbiological eradication rate confirmed those of the primary analysis indicating equal efficacy for both compounds. While patients receiving ciprofloxacin showed a significant increase of Extended Spectrum Beta Lactamase Producing-Escherichia coli (ESBL-E. Coli) colonization rates after 3-days treatment (6.9%), rates did not increase in patients receiving RIF-MMX (-0.3%). Both drugs were well-tolerated and safe. Conclusion: The novel multi-matrix formulation of the broad-spectrum, poorly absorbed antibiotic Rifamycin SV was found non-inferior to the systemic antibiotic ciprofloxacin in the oral treatment of non-dysenteric TD with the advantage of a lower risk of ESBL-E. Coli acquisition.