A new test has been made available to aid in the diagnosis of SIBO. The test is known as IBSchek and is available through Commonwealth Laboratories, Inc.

Here is a video of Dr. Pimentel discussing the test:

Finally, a blood test that can be used to diagnose SIBO. No more will anyone have to get complicated lactulose breath tests performed to diagnose their overgrowth.

Sadly, this is not the case.

IBSchek

The IBSchek blood test looks for two different antibodies to aid in the diagnosis of IBS / SIBO. The two antibodies are for CDT-b toxin and vinculin.1 2

When someone develops food poisoning, some of the toxins that the bacteria produce are known as Cytolethal Distending Toxin B or CDT-b toxin. Toxins are what make you ill when you get sick from food, in most cases the bacteria that you ingest from poorly prepared food are eliminated by stomach acid upon digestion. CDT-b toxin activates the TRPV1 receptors in the intestines (the same mechanism occurs when you ingest spicy foods), and this irritation causes the intestines to increase chloride and water secretion that causes diarrhea.3 Diarrhea is a defense mechanism by the body to eliminate the toxin quickly. Overgrowth of certain bacteria within the body are also able to produce ample amounts of Cytolethal Distending Toxin B, which can cause chronic diarrhea (IBS-C) similar to food poisoning.4 5

Your intestines have pacemaker cells that determine peristalsis (the waves that push matter through the intestines) known as the interstitial cells of Cajal. The ICC are fibroblast-like cells that act as a pacemaker for the MMC. One of the fundamental underlying causes of SIBO is dysfunction of the MMC, which causes the body not to be able to clear excessive bacteria out of the small intestine back into the large intestine. Excessive amounts of the CDT-b toxin might be able to destroy the interstitial cell of Cajal directly or by the toxin causing the body to produce antibodies against vinculin, harming the ICC later.6 7

Vinculin is a protein that helps connect the interstitial cells of Cajal so that they can be bonded together and communicate appropriately to help the MMC. When the CDT-b toxins harm the ICC, in a state of confusion the immune system “attacks” vinculin because it believes that it is a problem instead of the toxin. In doing so, the ICC are harmed by both the toxin itself and your overactive immune system. The “autoimmune condition” that was caused by the bacterial toxins reduces the function of the MMC significantly and leads to post-infection IBS also known as SIBO.8 9

Why IBSchek is Not a Good Diagnostic Test For SIBO

First off post-infectious IBS (SIBO) does not occur in most people recovering from food poisoning.

Only about 20% of individuals who get food poisoning will produce antibodies to the Cdt-b toxin and will have an autoimmune response to vinculin. If you do not have an appendix, there may be a greater chance of you developing post-infectious IBS (more on the importance of the appendix in a later post.)10 11

Post-infectious IBS is not always the cause of developing SIBO. Post-infectious IBS has occurred from viral gastrointestinal infections and is not known if it can be adequately tested using IBSchek. There are multiple causes of SIBO including, motility issues, PPI use, excessive antimicrobial use, loss of appendix, and infection.12 13

The test is only FDA approved to aid the diagnosis of IBS-D, so if you are suffering from IBS-C you are out of luck at the moment.14

The discovery of IBSchek and the test itself does have a few positives. IBSchek might be able to help diagnose people suffering from SIBO after contracting food poisoning. The test can also contribute to distinguishing between people suffering from post-infectious IBS from food poisoning and IBD.15

We also discovered more information about the different pathways associated with SIBO-D and might be able to use the new understanding of CDT-b toxin, vinculin, and the interstitial cells of Cajal, to help improve the lives of people with SIBO.

Hopefully, one day there will be a blood test that can completely aid us in the diagnosis of SIBO. Until then we will have to rely on breath tests, stool tests, and biopsies.