Objective: To investigate the incidence of small intestinal bacterial overgrowth (SIBO) and systemic low-grade inflammation in patients with irritable bowel syndrome (IBS). Methods: From June to October in 2017, 50 cases of IBS patients who met Rome Ⅳ criteria were consecutively collected at Outpatient Department of Gastroenterology of Shanghai Huashan Hospital. The incidence of SIBO was detected by hydrogen lactulose breath test (LBT) and methane LBT. The incidence of systemic low-grade inflammation in IBS patients was determined by fractional exhaled nitric oxide(FeNO) breath test. Chi-square test was used for statistical analysis. Results: Among 50 IBS patients, the positive rate of FeNO was 70%(35/50), and the number of FeNO positive cases in diarrhea-predominant (n=28), constipation-predominant (n=14) and mix-type (n=8) IBS paitents was 18, 11 and six, respectively, and the difference was not statistically significant among three groups (χ²=1.020, P=0.600). The incidence rate of SIBO was 60% (30/50), with 20 cases (40%) being only positive for hydrogen LBT, seven cases (14%) being methane LBT, and three cases (6%) being both positive. The numbers of hydrogen LBT and methane LBT in diarrhea-predominant, constipation-predominant, and mix-type IBS patents were 17, three, three and two, six, two, respectively. There were statistically significant differences in positive rates of hydrogen LBT and methane LBT among three groups (χ²=6.076 and 6.392, both P<0.05). The positive rate of FeNO in IBS patients with SIBO was higher than that of IBS patients without SIBO (90%, 27/30 vs. 40%, 8/20), and the difference was statistically significant (χ²=14.286, P<0.01). Conclusions Combination of hydrogen LBT and methane LBT has a higher detection rate of SIBO than traditional single hydrogen LBT. There is a correlation between SIBO and systemic low-grade inflammation in IBS patients.

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<0.01). Before treatment the score of IBS-QoL was (28.03±16.16), and decreased to (14.39±9.31) after treatment, and the difference was statistically significant (t=6.867, P<0.01). There was no significant difference in IBS-SSS and IBS-QoL scores among the diarrhea type, constipation type and mixed type groups (all 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.