Capsule takes bacteria samples as it moves through GI tract

Researchers have developed a swallowable tool that takes samples of bacteria as it moves through the gastrointestinal tract, an advance that could help doctors work out why a person has diabetes.

GI tract
(Purdue University photo/Mark Simons)

The GI tract, in addition to the colon, includes the mouth, oesophagus, stomach, pancreas, liver, gallbladder, small intestine and rectum.

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“It’s all about being able to take samples of bacteria anywhere in the gut. That was impossible before,” said Rahim Rahimi, an assistant professor of materials engineering at Purdue University, Indiana.

The tool is a drug-like capsule that passively moves through the gut without needing a battery. A pill version of a colonoscopy is already commercially available to view areas of the colon that a traditional colonoscopy cannot see, but neither tool can sample bacteria.

“If a colonoscopy or camera pill sees blood, it can’t sample that area to investigate further. You could just sample bacteria from a person’s faecal matter, but bacteria can vary a lot throughout the GI tract. Our approach could be complementary,” Rahimi said in a statement.

The bacteria-sampling capsule also would be a lot cheaper, each costing only about a dollar, he estimates.

Rahimi’s team is working on testing this capsule in pigs, which have a similar GI tract to humans. An initial demonstration of the prototype is published in RSC Advances.

The researchers 3D-printed the capsule out of resin. When exposed to the pH of a certain gut location, the capsule’s biodegradable cap dissolves. Inside the capsule, a hydrogel expands and collects intestinal fluid containing bacteria. Pressure closes capsule’s aperture when the sampling is complete.

The researchers have tested the prototype capsule in a culture solution designed to simulate the gut bacterial flora of a GI tract. They also tested the capsule’s ability to protect the sampled bacteria in different extreme environments. Their experiments so far show that the capsule could successfully sample bacteria common in the gut, such as E. coli, within an hour.

In a human, the capsule would continue to move throughout the GI tract with other faecal matter. A scientist could then recover the capsule from a study participant’s faecal matter, unscrew the capsule, and study the collected bacteria.

“This approach is providing new opportunities to study what type of bacteria are present in the gut. It would help us figure out how to manipulate these bacteria to combat disease,” Rahimi said.

A patent has been filed for this technology.