The Big Wiper asks:
My niece recently had a scare with some blood in her poop, but the doctor prescribed a course of antibiotics for her, telling her that she was likely suffering from food poisoning. That's a new one on me. How does food poisoning cause blood in the stool?
Dr. Adams responds:
Good question Wiper,
There are many different reasons that blood can appear in the stool. One of these has to do with certain infections. Some types of food poisoning or other intestinal infections are associated with bleeding. The main bacteria and parasites that can cause bloody diarrhea are Salmonella, Shigella, invasive E. Coli 0157, Campylobacter, Yersinia, and Entaomeba histolytica.
So why would I tend to suspect that bloody diarrhea is caused by an infection? Well, the history is very very important. It is important to ask about foods that were eaten in the prior few days, any history of travel, any sick contacts, fevers, sweats, aches, pains, vomiting, abdominal pain, and/or nausea. Most of these symptoms go along with an infectious process. In addition, an important sign of an infection seen when the vital signs are measured would be elevated body temperature (greater than 100.4). Blood work also is important as an elevated white blood cell count points an infectious cause of the bloody diarrhea.
Why do the bacteria and parasites I mentioned above cause bloody infectious diarrhea? The reason is that all of these microorganisms are INVASIVE. They not only infect and irritate the lining of the small and/or large bowel........they also INVADE the lining of our bowel and most will enter the blood stream. Many of these organisms also secrete toxins that cause further damage to the intestinal lining. A massive immune reaction commences in response to the infection, and this creates even more injury to the intestinal lining. The end result from all of this bombardment is bleeding, diarrhea, along with crampy abdominal pain, fever, and elevated white blood cell count.
Is there a treatment for infectious diarrhea? Sure there is. Antibiotics work very well. Typically, broad spectrum antibiotics will be used until the stool can be cultured for a specific microorganism.
Is there anything to be learned here? yes...........remember to cook your meat well.......wash your hands frequently, especially after using the bathroom and/or before preparing any food....do not drink water from streams or other non-purified sources....and if something looks bad or smells bad, it likely is spoiled, so do not eat it. Use common sense and you will stear clear of any intestinal infections.
Best regards,
-Dr. Adams
Dr. Adams is a resident in the Department of Internal Medicine at North Shore University Hopsital in Manhasset, NY. Got a question [1] for him?