Long-term outcomes of antibiotic combination therapy for ulcerative colitis

An antibiotic combination of amoxicillin, tetracycline and metronidazole (ATM) is effective for ulcerative colitis (UC), but this regimen is discontinued in some cases due to adverse events. This study aimed to assess a revised combination, namely, amoxicillin, fosfomycin and metronidazole (AFM), in UC patients with the goal of reducing side effects while maintaining therapeutic efficacy.

A prospective open-label trial was undertaken in 104 adult UC patients. A combination of oral amoxicillin (1500 mg), fosfomycin (3000 mg) and metronidazole (750 mg) was administered to patients daily for 2-4 weeks in addition to their conventional medication. Clinical assessment was performed using the Lichtiger index before treatment and at 0, 3, 6, 9 and 12 months and 2 and 3 years. Endoscopic evaluation was performed using the Mayo score before treatment and at 3 and 12 months.

The compliance rate was 99.2%. Response and remission rates were 80.8% and 63.5% at completion, 73.1% and 64.4% at 3 months, and 39.4% for both at 12 months, respectively. Of the 41 patients who were in remission at 12 months, 63.4% maintained that status until the 2-year follow-up. Similarly, 69.2% of those in remission at 2 years remained relapse free at the 3-year follow-up. Side effects were observed in 44.2% of the participants. Fever occurred in one patient (1.0%), which was lower than the rate observed with ATM therapy.

These results indicate that AFM therapy induces remission and is appropriate for long-term maintenance of UC while producing fewer and milder adverse events than ATM therapy.

This study was registered in the University Hospital Medical Information Network (No. R000046546).