An electronic nose for stomach infection

A portable ‘electronic nose’ that detects the signature gases produced by the common problematic gut pathogen Helicobacter pylori has been developed by researchers in Voronezh, Russia¹. The preliminary results, reported in the Journal of Analytical Chemistry, could provide an alternative to the invasive and expensive tests currently used to test for H. pylori infection.

“Our research group has been working for more than 25 years on the odours and volatile compounds of living systems, and have collected an enormous amount of data that we can use to solve health problems,” says lead researcher, Tatyana Kuchmenko, from Voronezh State University of Engineering Technologies. “From my own experience working with people suffering from gastrointestinal tract problems, particularly the elderly and children, I wanted to develop an alternative diagnostic test for Helicobacter pylori infection that doesn’t require an unpleasant fibrogastroscopy, or rely on expensive polymerase chain reaction tests, which may not always be available, especially in remote areas.”

H. pylori is one of the most common gastrointestinal infections, affecting up to half of the world’s population and implicated in gastritis, ulcers, and some cancers. Using an electronic nose consisting of an array of sensitive chemical sensors, the technique developed by Kuchmenko’s group exploits H. pylori’s unique ability to hydrolyse urea in the stomach, a reaction that produces ammonia and carbon dioxide.

“Our method measures certain biomolecules in the air from the mouth,” explains Kuchmenko. “We take an initial air sample in the mouth to record the state of the gastrointestinal tract and oral cavity, then the subject takes a urea solution, and we take mouth air samples every 5 minutes for up to 30 minutes. The results tell us the level of activity of the colonies of bacteria in the stomach or duodenum, and in children, even the location of those colonies.”

The procedure involves taking a 5 mL sample of air from the mouth using a syringe, and injecting the sample into the electronic nose, which has a specific sensors for ammonia, alkylamine vapours, carbon dioxide and organic acid vapours. After much testing, Kuchmenko’s team determined that ammonia was the key diagnostic gas, but the accuracy of the diagnosis can be greatly improved by mathematical analysis of a suite of parameters related to the by-products of H. pylori activity.

“We now have the possibility to complement the complex and unpleasant diagnosis for finding out a possible cause of stomach pain with a non-invasive breath test,” says Kuchmenko. “The electronic nose is painless, easy to use, affordable and accurate in our preliminary testing. It can also be used for patients of any age, at the bedside at home, in the clinic or ambulance.”