Small intestinal bacterial overgrowth (SIBO) is a common and an increasingly recognized disorder in liver cirrhosis, correlating with its severity. The prevalence of SIBO, assessed by the quantification of the bacterial density in the small intestinal aspirate, ranges from 30% to 73%. Multiple physiological derangements leading to SIBO appear in cirrhosis from decreased secretion of gastric acid, impaired mucosal immune response to decreased bile acid, and more importantly, intestinal dysmotility. The latter remains the most common predisposing factor in the pathogenesis of bacterial overgrowth. A recent pilot study using a wireless motility capsule (the SmartPill) demonstrated that patients with cirrhosis have significant delays in small bowel transit that is more pronounced in those with more severe liver disease. Altered small bowel motility in cirrhosis has been attributed to autonomic dysfunction, altered levels of circulating neuropeptides and the effects of inflammatory mediators on gut muscle and the enteric nervous system.
Hepatic Encephalopathy (HE) is a spectrum of neuro-cognitive impairment in cirrhosis that range from abnormal neuropsychiatric testing without clinical evidence of disease (Minimal Hepatic Encephalopathy\[MHE\]) to varying degrees of overt clinical findings: Overt Hepatic Encephalopathy (OHE). MHE is found in 30-84% of patients with liver cirrhosis. The neuro-cognitive deficit noted in MHE could predispose patient to impaired quality of life (QOL) which translates into lower QOL scores, higher risk of falls, driving problems and difficulties maintaining employment. Previous studies have shown that SIBO is prevalent and strongly linked to the pathogenesis of MHE. Consequently, altering and modulating the intestinal microbiota with ammonia-lowering and gut-selective agents has been the target treatment strategy. Multiple prior studies have evaluated Rifaximin efficacy in MHE and have shown improvements across a variety of study clinical end points including neuropsychiatric and QOL tests. However, the precise mechanism of action of Rifaximin in MHE is unclear. The proposed mechanisms by which Rifaximin may lead to improvement of MHE may be beyond the bactericidal/bacteriostatic effect, resulting in changes in bacterial metabolic function/virulence, to an anti-inflammatory and immune-modulatory effect.
The investigators hypothesize that Rifaximin may have an additional effect on small bowel motility that may be independent of its effect on bacterial overgrowth. The effect may not be necessarily through changes in patient's microbiome but rather through a pro-motility mechanism. The investigators intend to test this hypothesis by comparing the motility at baseline in cirrhotic patients with MHE and clinically significant portal hypertension, before and after treatment of SIBO with Rifaximin.
Aims:
1. To determine the therapeutic effect of Rifaximin on patients with CHE and underlying SIBO and as it is related to small bowel motility.
2. To determine the effect of Rifaximin on small bowel motility by using the SmartPill.
Study Design:
This is a prospective and interventional study. It will be conducted at the Gastroenterology and Hepatology outpatient clinics of MetroHealth Medical Center/Case Western Reserve University. Approximately 40 patients with liver cirrhosis will be assessed for eligibility by their hepatologist. Eligible patients will be referred to an expert psychologist for neuro-psychometric testing to confirm CHE. Then the patients with diagnosed with CHE will undergo Glucose Hydrogen Breath Test (BT) for SIBO screening. Subsequently, wireless motility capsule (the SmartPill) for motility testing will be performed in all patients with positive BT. Thereafter, cirrhotic patients diagnosed with both CHE and SIBO will be prescribed Rifaximin 550 mg PO twice daily for eight weeks. At the end of the treatment period, neuro-psychometric tests will be repeated to evaluate the therapeutic effect on CHE. In addition, BT and the SmartPill will be repeated at the completion of the treatment period with Rifaximin in order to assess the effect on small bowel motility.
