Efficacy of low dose and short-term rifaximin on irritable bowel syndrome related with small intestinal bacterial overgrowth

Objective To investigate the efficacy of low dose and short-term oral rifaximin in patients with small intestinal bacterial overgrowth (SIBO) related irritable bowel syndrome (IBS). Methods From June 2017 to June 2018, at the Department of Gastroenterology of Huashan Hospital, Fudan University in Shanghai, a total of 37 patients with SIBO related IBS were sequentially enrolled and divided into three groups: diarrhea type, constipation type and mixed type. All the patients received rifaximin 200 mg each time, three times per day for 14 days. The clinical efficacy before and after treatment were compared by the scores of irritable bowel syndrome symptom severity scale (IBS-SSS) and irritable bowel syndrome associated quality of life (IBS-QoL). The efficacy of rifaximin on SIBO clearance and SIBO related chronic low-grade inflammation was evaluated by lactulose breath test (LBT) and exhaled nitric oxide (eNO). T test and variance analysis were used for statistical analysis. Results Among 39 patients with SIBO related IBS, 24 patients were diarrhea type, seven were constipation type and six were mixed type. Except one patient quitted the study because of chest tightness and palpitation, the IBS-SSS score of the left 36 patients before treatment was (250.83±55.10), and decreased to (151.11±33.96), and the difference was statistically significant (t=13.686, P 0.05). After treated by rifaximin, the negative conversion rate of SIBO was 52.8%(19/36). The negative conversion rate of hydrogen LBT was 54.5%(12/22) and among 11 methane LBT positive patients, six cases turned negative; and one of three patients with both positive hydrogen LBT and methane LBT turned negative. The negative conversion rate of eNO was 41.7%(15/36). Conclusions Low dose and short term rifaximin treatment can improve the severity of clinical symptoms and quality of life in SIBO-related IBS patients, and the efficacy is not related with the subtypes of IBS. Key words: Irritable bowel syndrome; Small intestinal bacterial overgrowth; Lactulose breath test; Low-grade inflammation; Rifaximin