Irritable bowel syndrome (IBS) has been one of the most mysterious gastrointestinal (GI) disorders. We still don’t fully understand the condition, but as we learn more, we have been able to draw out a few potential causes. One common cause of IBS we see is foodborne illness, which is often referred to as post-infectious IBS (PI-IBS).
PI-IBS occurs after acute gastroenteritis (inflammation of the gut) caused by a foodborne illness. IBS symptoms, specifically diarrhea, can occur immediately after the foodborne illness has passed, or can take up to a year or more to present themselves. Studies across the globe show a 5-32% prevalence of PI-IBS after a foodborne illness. The most recent meta-analysis of research from the Mayo Clinic shows that one out of every nine people with a foodborne illness will end up with IBS.
Why is the link so strong? Infection and acute gastroenteritis leads to an autoimmune response that can cause gut nerve damage and dysfunction of the cells and migrating motor complex that regulate gut contractions. This leads to changes in gut motility that is a major marker for IBS. Infection and inflammation are also thought to increase intestinal permeability by damaging enterocytes, and alter the gut microbiome. All factors we know contribute to IBS.
Diarrhea-predominant IBS, known as IBS-D, is the most common form of PI-IBS. The more common pathogens that can lead to this are Campylobacter jejuni, Salmonella enterica, Shigella sonnei, E. coli, C. diff, and Giardia lambia. Infection with one of these pathogens can happen from contaminated water or produce, undercooked meats, food left out for long periods of time, not washing hands, other contact with the pathogens in the environment (ex: hospitals), and more. We see these infections most when people are traveling to underdeveloped countries, but they can happen to anyone, anywhere. The risk of PI-IBS is shown to increase in females, with anxiety disorders, and with a history of antibiotic use. Risk is shown to decrease as age increases, so onset may be more common among children.
PI-IBS is treated in a similar way to IBS-D. The use of the low FODMAP diet may help identify specific food triggers and reduce symptoms. Gut-directed hypnotherapy or cognitive behavioral therapy could be helpful, and medications may be used to reduce gut spasms. Antibiotic and probiotic therapy may also be used to treat the infection and rebuild the microbiome.
Something unique to PI-IBS is that symptoms have been shown to slowly decrease with time. They may last 8-10 years, but they could significantly improve in the first 2 years, which is encouraging for those dealing with this type.
Why is it important to know if your IBS is post-infectious? Knowing the cause of IBS can increase confidence in choosing treatment options, and knowing that your symptoms may improve over time can increase hope in the present moment. Knowing that you have PI-IBS can also be helpful for those who have had foodborne illness and are wondering why their symptoms are not improving.
In the past, PI-IBS was diagnosed using the Rome IV criteria (like every IBS diagnosis) and noting that symptoms occurred after a foodborne illness. The problem with this is that some people have no idea that their sickness is actually a foodborne illness, so they don’t state that they had one when they present their symptoms to their doctor. Also, symptoms could take a year to present themselves, and even longer for someone to go to the doctor out of concern, so the foodborne illness may a distant memory at time of diagnosis.
Now, we have an option for accurately spotting PI-IBS : IBS-smart! IBS-smart was created by doctors at Cedars-Sinai Medical Center after they found two antibodies, anti-CdtB and anti-vinculin, that are elevated in PI-IBS patients. These antibodies are involved in the autoimmune response that leads to the physiologic changes of the gut to develop IBS. Read more about their findings here.
IBS-smart is shown to be 90% specific in distinguishing IBS from IBD, which would be helpful to identify if IBS is overlapping with an IBD diagnosis. It is also shown to be 98% effective in identifying IBS, so you can be confident in a positive result.
The test is currently being used by many doctors around the country, and recently became available in Canada. You can talk with your doctor about ordering the test, or find a doctor in your area that is using the test here.
Want to learn more? I interviewed Dr. Pimentel, the leading researcher and developer of IBS Smart, to dig deeper into how IBS Smart works and what the value could be for you!
Erin: What does the process of ordering the test, taking it, then getting the results look like? What could someone expect?
Dr. Pimentel: You can simply log on to our website www.ibssmart.com/getdiagnosed and follow a few easy steps to request the ibs-smart test. The ibs-smart kit includes phlebotomy supplies and prepaid shipping materials and will be shipped directly to your home. Once you receive your kit you can bring it with you to any blood draw lab, along with your signed test order form to collect and ship your sample. Test results are reported within seven days of receiving your sample and include both qualitative and quantitative results.
Erin: Who is the test best used for? Who would the test not be effective for?
Dr. Pimentel: If you have chronic diarrhea and bloating with occasional pain or cramping, you may have IBS. It is the most common disorder in gastroenterology and one of the most common cause of visits to the doctor. However, recently a new test for the first time allows a patient or doctor to get to a diagnosis faster. This test is ibssmart which measures two antibodies. We now know that a large proportion of IBS sufferers have IBS starting from food poisoning which lead to autoimmunity and gut dysfunction. This new blood test assesses for this and hence can diagnose IBS within days (where it used to take years of unnecessary testing.
There are people who should be cautious when taking this test. If a person has blood in their stool, unexpected weight loss or are over the age of 45 and have never had a colonoscopy, they should see a doctor to be sure there is not some other diagnosis. However, if testing here is negative, ibssmart may still be helpful.
Erin: What happens with a positive test? What about a negative test?
IF: CdtB: Elevated; Vinculin: Not Elevated
Levels of anti-CdtB, a biomarker for post-infectious IBS, were elevated in your blood. While levels of anti-vinculin were not elevated, this still means that there is nearly a 90% likelihood that you have post-infectious irritable bowel syndrome (IBS). The cause is likely a long past infection from food poisoning that has developed into an autoimmunity driving your IBS symptoms.
IF: CdtB: Not Elevated; Vinculin: Elevated
Levels of anti-vinculin, a biomarker for post-infectious IBS, were elevated in your blood. While levels of anti-CdtB were not elevated, this still means that there is nearly a 90% likelihood that you have post-infectious irritable bowel syndrome (IBS). The cause is likely a recent infection from food poisoning.
IF: CdtB: Elevated; Vinculin: Elevated
Levels of both anti-CdtB and anti-vinculin, biomarkers for post-infectious IBS, were elevated in your blood. While levels of anti-CdtB were not elevated, this still means that there is a 98% likelihood that you have post-infectious IBS. The cause is likely a recent infection from food poisoning that has developed into an autoimmunity driving your IBS symptoms.
IF: CdtB: Not Elevated; Vinculin: Not Elevated
Levels of anti-vinculin or anti-CdtB, biomarkers for post-infectious irritable bowel syndrome (IBS), were not elevated in your blood. This means there is a very low probability that you have post-infectious IBS. You could still have IBS from a source other than gastroenteritis, or your symptoms may indicate a condition other than IBS.
Erin: What is the overall value of taking this test versus the traditional method of diagnosis?
Dr. Pimentel: What we know is that the sooner a patient gets a diagnosis for a disease, the sooner they get the right treatment. Some patients pay up to $20,000 in copays before they are told it’s IBS. These included so many negative investigations such as colonoscopy, ultrasounds, CT scans, stool testing and other blood work. Getting an answer in 48 hours would save that cost.
Besides the cost, this test tells the patient why they have IBS. This is important because if food poisoning did cause your IBS, you need to avoid further food poisoning which make your illness more severe, potentially.
Erin: How does this test change the treatment plan for a patient? How has the test revolutionized your work with IBS?
Dr. Pimentel: The test, when positive, points in the direction that IBS is a microbiome disease. In animal studies, when these antibodies are elevated, it leads to bacterial overgrowth. We know that antibiotics work in IBS but only found out why recently and bacterial overgrowth appears to be the reason.
The test has put the power back in the hands of patients. Patients get an answer that they have IBS. Now if the test if positive, IBS becomes a real disease, not a psychological condition. This is empowering for patients and doctors. I believe this second generation test, ibssmart is a gamechanger.