Description
Breath testing for Small Intestinal Bacterial Overgrowth (SIBO), measuring the gut bacterial fermentation products hydrogen and methane, is a robust method of assessing gut microbial activity. Breath gas production within 100 minutes of ingesting carbohydrates is diagnostic of SIBO.
Bacteria in the intestinal tract ferment ingested carbohydrates, gas byproducts pass across the gut wall into the circulation and are rapidly diffused by the lungs and exhaled in the breath.
Ambiguous gut symptoms following ingestion of foods, frequently diagnosed as Irritable Bowel Syndrome (IBS), have been associated with SIBO in up to 75% of these patients. The diagnostic method described here is largely unavailable in NHS gastroenterology departments because it’s considered a labour-intensive procedure for a chronic health condition.
Patients follow a strict low fermentable diet (low fibre, resistant starch, and complex carbohydrates) for 24 hours and fully fast for 12 hours (overnight) prior to the test to minimise normal colonic fermentation. Gas levels in a fasting breath sample are then compared against a subsequent nine samples collected at 20-minute intervals following ingestion of glucose. Increases in breath hydrogen, methane, or both, within the first 100 minutes of the test period are indicative of small intestinal bacterial activity, rapid absorption of glucose prevents any subsequent colonic fermentation. The lactulose challenge test is recommended if the assessment of bacterial activity in the distal end of the small intestine is required.
Methodology
Quintron BreathTracker SC instruments, the industry standard for breath hydrogen and methane analysis utilising gas chromatography incorporating solid-state sensors, are used for the measurement of breath gasses derived from intestinal bacterial fermentation of carbohydrates. Carbon dioxide levels are also measured permitting a correction of results based on the sample concentration of the alveolar air.
For the first time in the UK, Viva Health Laboratories have successfully concluded a comprehensive validation and verification assessment of the method using independently produced certified gasses.
Instrument calibration is performed at set daily intervals and certified quality assurance materials are used to assess analytical accuracy and precision.
Samples are collected using Quintron’s patented breath collection device utilising partially evacuated tubes with sample stability confirmed for up to 14 days.
When should I use
When the use of lactulose is contraindicated or for following up on negative lactulose SIBO results where upper GI fermentation is suspected (glucose is more easily fermented by bacteria than lactulose).
Patients with an unresolved diagnosis of IBS, diarrhoea, constipation, postprandial bloating, abdominal discomfort and pain, a history of gastroenteritis, intestinal surgery, Crohn’s disease, coeliac disease, pancreatitis, impaired gut motility or use of proton pump inhibitors (PPIs) are at risk of SIBO and should be considered for screening.
Other Details
Consider using lactulose SIBO breath test.
Following a rapid rise in hydrogen levels (within the first 20 minutes) consider possible gastric helicobacter pylori infection.
