Rifaximin Fails to Prevent Campylobacteriosis in the Human Challenge Model: A Randomized, Double-Blind, Placebo-Controlled Trial

Background. Campylobacter species are a leading cause of diarrheal disease globally with significant morbidity. Primary prevention efforts have yielded limited results. Rifaximin chemoprophylaxis decreases rates of travelers' diarrhea and may be suitable for high-risk persons. We assessed the efficacy of rifaximin in the controlled human infection model for Campylobacter jejuni. Methods. Twenty-eight subjects were admitted to an inpatient facility and randomized to a twice-daily dose of 550 mg rifaximin or placebo. The following day, subjects ingested 1.7 × 10⁵colony-forming units of C. jejuni strain CG8421. Subjects continued prophylaxis for 3 additional days, were followed for campylobacteriosis for 144 hours, and were subsequently treated with azithromycin and ciprofloxacin. Samples were collected to assess immunologic responses to CG8421. Results. There was no difference (P = 1.0) in the frequency of campylobacteriosis in those receiving rifaximin (86.7%) or placebo (84.6%). Additionally, there were no differences in the clinical signs and symptoms of C. jejuni infection to include abdominal pain/ cramps (P = 1.0), nausea (P = 1.0), vomiting (P = .2), or fever (P = 1.0) across study groups. Immune responses to the CG8421 strain were comparable across treatment groups. Conclusions. Rifaximin did not prevent campylobacteriosis in this controlled human infection model. Given the morbidity associated with Campylobacter infection, primary prevention efforts remain a significant need.