Small Intestinal Bacterial Overgrowth in Patients with Interstitial Cystitis and Gastrointestinal Symptoms

Purpose Interstitial cystitis (IC) often coexists with irritable bowel syndrome (IBS). IBS may be explained by small-intestinal bacterial overgrowth (SIBO), which increases immune activation and visceral hypersensitivity. This prospective pilot study tested hypotheses that IC patients with gastrointestinal (GI) symptoms have SIBO, that nonabsorbable antibiotic use improves symptoms, and that improvement is sustained by prokinetic therapy. Methods Consecutive IC patients with GI symptoms had lactulose breath testing (LBT). Those with abnormal results received rifaximin 1,200–1,800 mg/day for 10 days then tegaserod 3 mg/nightly. Questionnaires addressed IC and GI global improvement. Results Of 21 patients, 17 (81%) had abnormal LBTs. Of 15 patients treated, GI global improvement was moderate to great in 11 (73%) and sustained in ten (67%). IC global improvement was moderate to great in six (40%) and sustained in seven (47%). Conclusions A majority of IC patients and GI symptoms had an abnormal LBT suggesting SIBO. Rifaximin improved symptoms, which was sustained by tegaserod.