Mycobacterium avium subspecies paratuberculosis has been proposed as a cause of Crohn's disease.
Dr Warwick Selby and colleagues conducted a prospective, parallel, placebo-controlled, double-blind, randomized trial of 2 years of clarithromycin, rifabutin, and clofazimine in active Crohn's disease.
The team then undertook a further year of follow-up.
|59% of the antibiotic group relapsed|
The team assessed 213 patients.
The patients were randomized to clarithromycin 750 mg/day, rifabutin 450 mg/day, clofazimine 50 mg/day or placebo.
In addition, the patients were allocated to a 16-week tapering course of prednisolone.
Those in remission at week 16 continued their study medications in the maintenance phase of the trial.
Primary end points were the proportion of patients experiencing at least 1 relapse at 12, 24, and 36 months.
The research team found at week 16 that 66% of subjects were in remission in the antibiotic arm vs 50% in the placebo arm.
Of 122 subjects entering the maintenance phase, 39% taking antibiotics experienced at least 1 relapse between weeks 16 and 52, compared with 56% taking placebo.
At week 104, the team noted that the results were 26% and 43%, respectively.
The team found that during the following year, 59% of the antibiotic group and 50% of the placebo group relapsed.
Dr Selby's team concluded, "Using combination antibiotic therapy with clarithromycin, rifabutin, and clofazimine for up to 2 years, we did not find evidence of a sustained benefit."
"This finding does not support a significant role for Mycobacterium avium subspecies paratuberculosis in the pathogenesis of Crohn's disease in the majority of patients."
"Short-term improvement was seen when this combination was added to corticosteroids, most likely because of nonspecific antibacterial effects."