IBD TESTS FOR INFECTIONS IN THE INTESTINE

Intestinal infections can make Crohn's disease and ulcerative colitis much worse. And sometimes treating them can quickly calm IBD symptoms down. But because most of the infections are treated differently, it's important to know what kind of infection it is. And the only way to do that is to collect a sample from the intestine and send it to the lab. 

Stool culture looks for bacteria in the intestine. Salmonella, Shigella, and E coli are some common ones that can be tested for. Yersinia and Campylobacter are particularly important because infections with these bacteria can look similar to Crohn's disease.  

Clostridium difficile is a well-known infection that is common in IBD. It can be accompanied by blood, diarrhea and pain, similar to IBD itself. The newer DNA or PCR test for C diff, as it is known, can show that C diff is present, while the toxin indicates an infection is present–but it still can take several specimens to detect the bacteria. 

Ova and Parasites (O & P) is often done to look for parasites or their eggs (ova). These infections can cause diarrhea, pain and sometimes nausea, but only a few (amoeba) will cause blood.

Certain viruses can cause sudden infection but these, rotavirus and norovirus, usually fade away within a few days. Others, adenovirus and cytomegalovirus, can persist and can longer infections that can mimic IBD or make it worse. These can all be tested for, though the last two are often better tested for at the time of a colonoscopy. 

Combined PCR tests can be done for viruses, parasites and bacteria at the same time. This usually is done on stool that is loose or diarrhea. The intestine has numerous other bacteria and parasites that are part of the healthy intestinal flora (or microbiome). These are generally done for research purposes to see the the effects of diet, disease and medicines. At this moment, no reliable tests are commercially available to characterize or measure these populations of the normal intestine—but that will probably happen soon.