Small Intestine Bacterial Overgrowth

doi:10.1016/S0016-5085(79)91337-4

Gastroenterology

Volume 76, Issue 5, Part 1, May 1979, Pages 1035-1055

https://doi.org/10.1016/S0016-5085(79)91337-4 Get rights and content

The gastrointestinal tract proximal to the distal ileum is usually sparsely populated with bacteria. When overgrowth of bacteria in the small intestine is accompanied by nutrient malabsorption and clinical manifestations of weight loss and malnutrition, the setting has been called the stasis, stagnant loop, or blind loop syndrome. Since the publication of a number of excellent general reviews of the subject several years ago, ^1–4 there has been an increased understanding of some of the pathophysiologic events accompanying overgrowth of bacteria in the small intestine. In particular attention has been drawn to the potential addition of mucosal injury to disturbances of the intraluminal environment in the altered handling of various nutrients. In addition, clinical recognition of the entity has increased with the use of noninvasive screening tests, with improvement in culture technique, and with increased recognition of several types of disordered intestinal motility predisposing to overgrowth. The purpose of this review will be to (a) analyze recent developments in the understanding of this syndrome, putting them into perspective with the previously reviewed material; (b) point out the clinical ramifications of the recent information, especially with the perspective that most conditions predisposing to bacterial overgrowth are lifelong, once present; and (c) suggest several areas where future investigation might prove fruitful in furthering our understanding of the pathophysiology and management of small intestine bacterial overgrowth.

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Cited by (285)

COLIGENTA treatment of small intestinal bacterial overgrowth. Results of an open study.
2021, Digestive and Liver Disease
The treatment of small intestinal overgrowth (SIBO) varies according to the center. The present study aimed to evaluate the efficacy of COLIGENTA, an association of colimycin and gentamycin, on SIBO symptomatology and breath test normalization
In this prospective cross-sectional open study, 150 patients with functional bowel disorders and SIBO diagnosed by lactulose hydrogen breath test (LHBT) underwent COLIGENTA oral treatment. A new HLBT was performed 4 weeks after the first HLBT.
The patients were mainly female (74%), with a mean age of 47.4 ± 16.2 years and a body mass index of 26.2 ± 5.9 kg/m². After treatment, a decrease of expired hydrogen concentration (P<0.001) was found in the entire population. Improvement of gastrointestinal symptoms was found in 129 patients (86%), while the breath test's normalization was found in 62 patients (42%). Logistic regression showed that normalization of bowel symptoms was not associated with demographics, clinical, or hydrogen breath concentration. In contrast, normalization of LHBT was associated with an increase of breath hydrogen concentration at time 100 min during the first test (P = 0.003; OR=1.072; 95%CI= [1.023–1.123]).
The present study shows that 10-days of COLIGENTA treatment has a high SIBO clinical improvement rate and can be used as the first or second treatment line.
AGA Clinical Practice Update on Small Intestinal Bacterial Overgrowth: Expert Review
2020, Gastroenterology
Thanks to ready access to hydrogen breath testing, small intestinal bacterial overgrowth (SIBO) is now commonly diagnosed among individuals presenting with a variety of gastrointestinal and even nongastrointestinal symptoms and is increasingly implicated in lay press and media in the causation of a diverse array of disorders. Its definition, however, remains controversial and true prevalence, accordingly, undefined. The purpose of this review, therefore, was to provide a historical background to the concept of SIBO, critically review current concepts of SIBO (including symptomatology, pathophysiology, clinical consequences, diagnosis and treatment), define unanswered questions and provide a road map toward their resolution.
Best Practice Advice statements were developed following discussion by the 3 authors. Two authors each developed text around certain Best Practice Advice based on a review of available literature. All 3 authors reviewed the complete draft and after discussion, redrafting, and further review and revision, all of the authors agreed on a final draft.
The definition of SIBO as a clinical entity lacks precision and consistency; it is a term generally applied to a clinical disorder where symptoms, clinical signs, and/or laboratory abnormalities are attributed to changes in the numbers of bacteria or in the composition of the bacterial population in the small intestine.
Symptoms traditionally linked to SIBO include bloating, diarrhea, and abdominal pain/discomfort. Steatorrhea may be seen in more severe cases.
There is insufficient evidence to support the use of inflammatory markers, such as fecal calprotectin to detect SIBO.
Laboratory findings can include elevated folate and, less commonly, vitamin B-12 deficiency, or other nutritional deficiencies.
A major impediment to our ability to accurately define SIBO is our limited understanding of normal small intestinal microbial populations—progress in sampling technology and techniques to enumerate bacterial populations and their metabolic products should provide much needed clarity.
Controversy remains concerning the role of SIBO in the pathogenesis of common functional symptoms, such as those regarded as components of irritable bowel syndrome.
Management should focus on the identification and correction (where possible) of underlying causes, correction of nutritional deficiencies, and the administration of antibiotics. This is especially important for patients with significant maldigestion and malabsorption.
Although irritable bowel syndrome has been shown to respond to therapy with a poorly absorbed antibiotic, the role of SIBO or its eradication in the genesis of this response warrants further confirmation in randomized controlled trials.
There is a limited database to guide the clinician in developing antibiotic strategies for SIBO, in any context. Therapy remains, for the most part, empiric but must be ever mindful of the potential risks of long-term broad-spectrum antibiotic therapy.
Clinical conditions associated with bacterial overgrowth
2019, Gastrointestinal Diseases and Their Associated Infections
Emerging evidence suggests that many gastrointestinal diseases are associated—if not caused—by alterations in the gut microbiome. Specific microbiome signatures have been reported for irritable bowel syndrome and inflammatory bowel disease, and these have been associated with pro and antiinflammatory effects contributing to disruption or maintenance of gut homeostasis. Small intestinal bacterial overgrowth (SIBO) is a well-established example of small intestinal dysbiosis. SIBO is defined as a heterogeneous syndrome with excessive and/or abnormal type of bacteria in the proximal small bowel. In addition to increased microbial density, loss of microbial diversity of microbes colonizing the gut mucosa—also labeled as the mucosa associated microbiome (MAM)—is the key finding. However, thus far the translation of this new knowledge into clinical practice and the ability to specifically target alterations of the bacterial colonization of the gut are hampered by the lack of valid and readily available clinical tests to diagnose gut microbial dysbiosis. In the past, culture of jejunal fluid aspirate is considered the “gold standard” for diagnosing dysbiosis, including SIBO, but is rarely used in the clinical setting. Breath tests measuring hydrogen and methane in the exhaled breath—preferentially after a glucose test meal—are simple and widely utilized in the routine clinical setting, but their sensitivity and specificity is far from optimal. In the future utilization of molecular technologies, high throughput will enable us to identify “biomarkers” for various GI and non-GI diseases that will guide therapy.
An in-vitro upper gut simulator for assessing continuous gas production: A proof-of-concept using milk digestion
2018, Journal of Functional Foods
Using gases as biomarkers is receiving increasing attention across the field of gut health. The use of in-vitro digestion systems that measure gas is common to understand some of the complex systems that create these gases and previously have been conducted using long time period sampling schemes which miss important signatures regarding the dynamics of gas production. Here the development of a mono-compartment in-vitro digestion simulator capable of recording vital dynamic information in real-time including: CO₂ concentration; high sensitivity H₂ concentration; and pH are presented and validated utilising milk. The impact of a simplified bacterial model, bacterial population size and the presence of lactase are investigated. The favourable gas production outcomes are obtained when lactase is present, at 10⁶ CFU of bacteria, in good agreement with clinical observations. This proof-of-concept system demonstrates reliable and repeatable results and has the potential to enhance the information capacity of current and future in-vitro simulators.
Chronic pancreatitis and small intestinal bacterial overgrowth
2018, Pancreatology
Increased urinary indoxyl sulfate (indican): New insights into gut dysbiosis in Parkinson's disease
2015, Parkinsonism and Related Disorders
Changes in the composition of gut microflora have been associated with an increase in chronic diseases. Indican urinary concentration is one of the most common and easily assessable markers of intestinal dysbiosis. Little information is available on intestinal dysbiosis in Parkinson's disease (PD). We decided to investigate indican urinary concentrations in a cohort of PD patients.
A case–control study including PD patients (N = 68) on treatment with levodopa (PD) or on no pharmacological treatment (De Novo, DPD; N = 34) and an age and gender-matched healthy control group (CTR; N = 50). Main confounders, such as nutritional habits and constipation diagnosed according to Rome III criteria, were also investigated.
Indican urinary concentrations were significantly higher in PD and DPD than in CTR (P < 0.001 and P < 0.01, respectively). In PD patients the concentrations were unrelated to the presence of constipation, whereas this symptom was associated with higher concentrations in controls (P = 0.043). The frequency of dairy product consumption was also positively associated with increased concentrations (P = 0.008). Predictors of indican concentrations were sought by multivariate linear regression analysis. The higher indican urinary concentrations found in both DPD (P = 0.045) and PD (P = 0.023) patients persisted after adjustment for age, gender, BMI, constipation and consumption of dairy products.
Gut dysbiosis seems to be an important issue in PD, independently of the presence of constipation and starting from the early stages of the disease. The role of gut dysbiosis in the pathogenesis of PD deserves further investigation.

View all citing articles on Scopus

: This study was supported in part by Grant RR-82 from the National Institutes of Health. Dr. King is the recipient of a Research Associate Award from the Veterans Administration. Dr. Toskes was a Clinical Investigator with the Veterans Administration during preparation of this review.

: The authors acknowledge the fine secretarial assistance of Mrs. Frances T. Tucker.

View full text

Small Intestine Bacterial Overgrowth

Gastroenterology

Gastroenterology

Gastroenterology

Gastroenterology

Am J Clin Nutr

Gastroenterology

Am J Clin Nutr

Gastroenterology

Gastroenterology

Microflora. Gastroenterology

Am J Clin Nutr

Gastroenterology

Gastroenterology

Gastroenterology

Am J Med

Anaerobic bacteria as cause of the blind loop syndrome: a case report with observations on response to antibacterial agents

Lancet

Gastroenterology

Am J Clin Nutr

Am J Clin Nutr

Am J Clin Nutr

Am J Clin Nutr

Blood

Gastroenterology

Lancet

Lancet

Gastroenterology

Pharm Res Comm

Lancet

Lancet

Gastroenterology

Lancet

Small bowel bacterial overgrowth

Adv Intern Med

The pathophysiological role of small intestinal bacterial flora

Scand J Gastroenterol Suppl

Intestinal absorption in the “contaminated smallbowel syndrome.” Gut

Studies on the intestinal flora. l. The bacterial flora of the gastrointestinal tract in healthy and achlorhydric persons

Gastroenterology

Assessment and significance of bacterial overgrowth in the small bowel

Q J Med

Normal viral and bacterial flora of the human small and large intestine

N Engl J Med 274:500-505

Studies on the intestinal flora. II. Bacterial flora of the small intestine in patients with gastrointestinal disorders

Gut

Gastrocolic fistula complicating transmural colitis: report of a case and review of the literature

Mt Sinai J Med NY

Intestinal bacterial flora and bile salt studies in hypogammaglobulinaemia

Gut

Effect of bile and deoxycholate on gram-negative anaerobic bacteria

Appl Microbiol

Effects of biliary diversion on intestinal microflora in the rat

J Med Microbiol

The bacterial content of the small intestine in normal and cirrhotic patients: relation to methionine toxicity

Clin Sci

Bacteria, bile, and the small bowel

Gut

Influence of gastric pH on gastric and jejunal flora

Gut

Gastric pH and microflora of normal and diarrhoeic infants

Gut

Studies of the small-intestinal bacterial flora and of intestinal absorption in pernicious anemia

Am J Dig Dis

Assessment of the relationship between gastric secretory capacity and jejunal bacteriology

Scand J Gastroenterol

Bacterial flora of the jejunum following peptic ulcer surgery

Arch Surg