small intestine bacterial overgrowth symptoms

Diagnosis of SIBO is challenging, as illustrated by 1 study in which mean total symptom scores were similar regardless of whether patients tested positive or negative with duodenal aspirate and breath testing ( P = 0.9) ( 6). Typically, over two-thirds of patients report the aforementioned symptoms ( 6,7).

Symptoms of SIBO are nonspecific and include abdominal pain, belching, bloating, diarrhea, distension, flatulence, and indigestion that overlap and vary in frequency, duration, and severity. CLINICAL FEATURES, PREVALENCE, AND PATHOETIOLOGY Our review primarily focuses on these patients, as they are most commonly encountered in gastroenterology clinics, but other conditions are appropriately referenced wherever necessary. Although we recognize that SIBO occurs in a wide spectrum of diseases discussed below, most literature on this topic has focused on patients presenting with either unexplained symptoms or symptoms of irritable bowel syndrome (IBS).

A total of 23 references on predisposing factors and 4 on diagnostic testing for SIBO were included. METHODSĪ PubMed search was performed on June 8, 2018, to identify English-language publications of clinical trials pertaining to SIBO in adults since 1985 using the search terms “small bowel bacterial overgrowth,” “small intestinal bacterial overgrowth,” “SIBO,” “epidemiology,” “diagnosis,” “treatment,” “antibiotic (e.g., ciprofloxacin, cotrimoxazole, and metronidazole),” “rifaximin,” or “probiotic.” Clinical studies of rifaximin ( n = 15), systemic antibiotics ( n = 6), and probiotics ( n = 3) in SIBO were included, whereas studies of combination therapies, for example, rifaximin with another antibiotic and/or other combination of systemic antibiotics or probiotics, were excluded from this review. The purpose of this article is to provide an up-to-date review of SIBO, including symptom patterns, predisposing risk factors, prevalence, specialized diagnostic testing, and potential therapeutic interventions, and to describe gaps in our knowledge and unmet needs. Small intestinal bacterial overgrowth (SIBO) is characterized by the presence of an abnormal amount of bacteria in the small intestine together with a constellation of GI symptoms. Bacterial concentrations increase progressively along the small intestine ( 4,5). Culture-independent methods, such as next-generation sequencing, show low concentration of distinct bacterial populations in the duodenum of healthy individuals, in contrast with bacterial populations that inhabit the mouth ( 3). The adult gastrointestinal (GI) tract has the largest microbial population in the human body ( 1) the predominant site is the colon, containing 38 trillion bacteria ( 2).

Through improved awareness and scientific rigor, the SIBO landscape is poised for transformation. However, 15 studies have shown rifaximin, a nonsystemic antibiotic, to be effective against SIBO and well tolerated. Limited numbers of controlled studies have shown systemic antibiotics (norfloxacin and metronidazole) to be efficacious. Treatment, usually with antibiotics, aims to provide symptom relief through eradication of bacteria in the small intestine. Glucose or lactulose breath testing is noninvasive but an indirect method that requires further standardization and validation for SIBO. Small bowel aspirate/culture with growth of 10 3–10 5 cfu/mL is generally accepted as the “best diagnostic method,” but it is invasive. Predisposing factors include proton-pump inhibitors, opioids, gastric bypass, colectomy, and dysmotility. Although abdominal bloating, gas, distension, and diarrhea are common symptoms, they do not predict positive diagnosis. Its prevalence is unknown because SIBO requires diagnostic testing. Small intestinal bacterial overgrowth (SIBO) is a common, yet underrecognized, problem.

Small intestine bacterial overgrowth symptoms