Bacterial overgrowth

Delays of more than two hours after the collection is completed may lead to markedly erroneous results. Urines with bacterial overgrowth, hemolyzed blood, or those obtained following any type of instrumental examination of the urinary tract may also lead to erroneous results, and should not be used for assays of enzyme activities. The stability of some clinically important enzymes in the various body fluids is given in Table IV. 

Disruption of host defenses owing to intravenous catheters, indwelling Foley catheters, burns, trauma, surgery, and increased gastric pH (secondary to antacids, H2 blockers, and proton pump inhibitors) may place patients at higher risk for infection. Breaks in and entry into the skin provide a route for infection because the natural barrier of the skin is disrupted. Increased gastric pH can allow for bacterial overgrowth and has been associated with an increased risk of pneumonia.18... 

Diarrhea Drug related Antibiotic-induced bacterial overgrowth Hyperosmolar medications administered via feeding tubes Antacids containing magnesium Malabsorption Hypoalbuminemia/gut mucosal atrophy Pancreatic insufficiency Inadequate GIT surface area Rapid GIT transit Radiation enteritis Tube feeding related Rapid formula administration Formula hyperosmolalty Low residue (fiber) content Lactose intolerance Bacterial contamination... 

Bacterial overgrowth Pathogenesis Gastrointestinal motility Gastric acid Malabsorption syndromes... 

When the mechanisms restricting bacterial colonization in the upper gut fail, due to disease or dysfunction, bacterial overgrowth develops. The segmental distribution may be gastric, intestinal or both depending on the type of failure. The consequences for the host vary from none to life-threatening complications, caused by severe water and electrolyte deficiencies and septic manifestations. 

The predominant quotation in the literature is purely quantitative with 105 CFU/ml of small intestinal aspirate as a limit [2, 6-8]. In symptomatic bacterial overgrowth, Gram-negative bacilli are present in the small intestine, making the flora colonic-like [2, 7]. The term bacterial... 

Culture of intestinal contents is the gold standard for detecting bacterial overgrowth [2, 7, 9], This technique allows both segmental localization and the identification required to distinguish between URT and Gram-negative bacilli, respectively. The labor intensity and cost, however, make its clinical use difficult. 

The pathogenesis of bacterial overgrowth is reviewed by considering separately the consequences of failure of the two main defense mechanisms in the upper gut responsible for the two types of bacterial overgrowth (table 1) the gastric acid barrier and intestinal clearance. 

Features of the two main types of bacterial overgrowth, defined by the underlying pathogenesis (see text for details of the failure required to alter the microflora of the upper gut, and the diseases and clinical conditions that can lead to failure of the gastric acid barrier and intestinal clearance, respectively). GNB = Gram-negative bacilli. a > 105 CFU/ml of fasting luminal contents. 

The consequence of bacterial bile acid metabolism [66, 74,77] is hardly clinically significant malabsorption [6] in otherwise healthy individuals [32,79], but in predisposed individuals this may be different. Accordingly, omeprazole interferes with the absorption of vitamin B12 [80-83] and protein assimilation [84], The mechanism for altered vitamin B12 absorption is prevention of its cleavage from dietary protein [83], for which the importance of the concurrent bacterial overgrowth has not yet been ruled out. 

Summary of Failure of the Gastric Acid Barrier Intestinal Bacterial Overgrowth When the gastric acid barrier fails the bacterial counts in the most proximal part of small bowel increase. Stan-... 

If anatomical abnormalities have been ruled out, testing of the small bowel motor activity is useful to elucidate the pathogenesis of bacterial overgrowth with Gram-negative bacilli (table 1). This choice is encouraged by the correlation between clinical disorders associated with bacterial overgrowth and disorders associated with dysmotility of the small bowel [113]. 

Stanghellini et al. [122] have carefully defined the most common abnormalities of phase III activity and other abnormal motility patterns that occur in patients with chronic intestinal pseudoobstruction, who often suffer from bacterial overgrowth [113], This concerns phase III with abnormal migration (stationary or retrograde) and with abnormal isotonic component, abnormal burst activity, and a failure of the postprandial pattern. 

Breath tests are, therefore, less useful for testing of intestinal transit in the presence of bacterial overgrowth. 

Anatomical changes can alter luminal flow into a surgically prepared blind loop, a diverticulum, or through a fistula. These anatomical abnormalities of relevance for the development of bacterial overgrowth have been carefully defined in previous literature [2, 7,98]. 

Inflammation. Chronic inflammatory bowel disease affecting the small bowel can lead to disturbances of intestinal motility [146], Potential mechanisms are previous surgery, development of fibrosis and strictures, malabsorption, and cross-talk between inflammatory and enteric nerves [156, 157], Patients with Crohn s disease are often included in aggregate studies of bacterial overgrowth [23, 75, 158], reflecting this link. 

Connective Tissue Diseases. Scleroderma is the connective tissue disease most frequently associated with intestinal dysmotility and bacterial overgrowth [159, 160]. Although the motility of the esophagus is most frequently affected, and a prerequisite for the label CREST syndrome, small bowel involvement is seen in a proportion of these patients. When present, intestinal clearance is usually impaired because of shallow contractions resulting in ineffective peristalsis and clearance. This can lead to overgrowth with Gram-negative bacilli, in part responsible for the malabsorption [161]. 

Patients with advances liver cirrhosis often suffer from bacterial overgrowth [175], Chang et al. [176] reported a reduced frequency and rate of migration for migrating motor complexes in patients with liver cirrhosis, alterations that predispose to colonization of the small bowel by Gram-negative bacilli [12],... 

Yantrappen et al. [23] for the first time showed the relevance of phase III of the migrating motor complex in the current context, when reporting its absence in 5 of 12 patients with bacterial overgrowth detected by the bile acid breath test and response to antibiotics. 

Blood donors with selective IgA deficiency have a normal gastrointestinal microflora without evidence of bacterial overgrowth [191]. In patients with complex immunodeficiency increased bacterial colonization is seen in... 

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