Sorry, you need to enable JavaScript to visit this website.

The sniff of health – Scientists design improved methods to diagnose intestinal infections using breath

Read time: 3 mins

Photo: Siddharth Kankaria / Research Matters

There is a lot in the air – especially in the one we breathe out! Now, a new study by Prof. Manik Pradhan’s team at the S. N. Bose National Centre for Basic Sciences, Kolkata, in collaboration with the eminent gastroenterologist and medical scientist Dr. Sujit Chaudhuri at AMRI Hospital, Kolkata, claims to accurately diagnose intestinal diseases by analyzing a patient’s breath. It proposes an improved methodology that can help early diagnosis of intestinal disorders like Irritable Bowel Syndrome (IBS) affecting the large intestine, and Small Intestinal Bacterial Overgrowth (SIBO) affecting the small intestine.

IBS and SIBO are chronic disorders that often cause severe pain, diarrhea and affect the individual’s quality of life. In some cases, they may lead to depression and anxiety, affecting productivity. Studies have shown that those suffering from IBS could also have SIBO, and an early, accurate diagnosis may benefit patients.

Existing tests to diagnose SIBO such as blood tests, endoscopy and hydrogen breath test are expensive, time consuming and often inaccurate. An endoscopy, where a flexible tube with a light and camera is inserted in the digestive track to examine the upper intestinal track, can cost about INR 3000 per session. “There is a pressing need to develop a new strategy that makes the detection of SIBO more sensitive and precise”, remarks Dr. Pradhan.

In this study, the researchers have proposed an improvement to the existing Hydrogen Breath Test (HBT) where instead of measuring the amount of hydrogen in a patient’s breath, they propose to measure hydrogen sulphide. Hydrogen sulphide is a foul smelling gas that resembles the smell of rotten eggs and is produced in the large intestine by sulphate reducing bacteria. In case of patients with SIBO with diarrhea, there is an overgrowth of sulphate reducing bacteria, which increases the production hydrogen sulphide. This gas is then transported to the lungs by the bloodstream and expelled in the breath, leaving behind clues for diagnosis. The level of hydrogen sulphide in breath of normal individuals lies in the range of 1-10 ppm, but for SIBO patients, the level is increased 2-3 fold from the base level.

The researchers analysed the breath of 150 individuals suffering from IBS by collecting their breath samples after a 10-12 hour fasting period where they were only allowed to drink water. These samples were then tested for presence of hydrogen sulphide. “The diagnostic sensitivity of the conventional Hydrogen Breath Test is only 46% and the results are highly controversial. On the other hand, the diagnostic accuracy of HSBT is more than 90% for IBS patients who are suffering from SIBO for assessment of SIBO in IBS patients”, says Dr. Pradhan.

The test also works accurately for patients who earlier had SIBO, but has been cured with antibiotic therapy, thus helping early diagnosis and follow-up. It also promises to be cost effective too. “We believe that the test will be much cheaper compared to the conventional endoscopy-based test that currently in practice”, says Dr. Pradhan.

The team, including Ph.D. scholars Mr. Gourab Dutta Banik and Mr. Suman Som, is continuing their research to make this test clinically viable and use it as a regular diagnostic procedure. “We are looking to identify new potential biomarkers of SIBO in exhaled breath by using high resolution spectroscopy technique. We hope that our research will pave the way for a novel strategy in preventing or treating the deleterious effects of SIBO and IBS”, concludes Dr. Pradhan.