Acute Bloody Diarrhea

Today's case involved an older man with an acute history of watery, bloody diarrhea.  He had a history notable for radiation to the abdomen.  His stool studies later became positive for Campylobacter (and he actually had a Campylobacter bacteraemia).  In addition, his stool ova and parasites were positive for Entamoeba  histolytica.

There were some valuable learning points today:

-Acute diarrhea is a common presenting illness both in primary care and in our hospital settings.  The differential diagnosis is substantially different for acute and chronic diarrhea (see previous blog post on chronic diarrhea).  Acute diarrhea is generally caused by infections.

-The history is helpful in determining the cause of the patient’s symptoms.  First and foremost, the duration of symptoms and the qualities of the stool (watery, loose, bloody, mucousy, etc.) are important.  Other useful information would be a travel history, history of antibiotic use, recent sick contacts, exposure to other people with diarrheal illnesses, presence of upper gastrointestinal symptoms, recent consumption of undercooked meats/eggs/poultry or unpasteurized milk, and a past medical history of immunocompromise.  Also, we mentioned several cases in which rectal sexually-transmitted diseases have presented as “diarrhea” even though the primary issue is usually rectal pain and discharge; therefore, taking a sexual history is also helpful.  In younger patients, a new presentation of an inflammatory bowel disease like Crohn disease or Ulcerative colitis should be considered.  Don’t forget that there is a bimodal distribution of new diagnoses of IBD, and that elderly people in their 50’s to 80’s can also newly develop IBD.  In their differential diagnosis, things like microscopic colitis and ischemic colitis usually also need to be considered.

-The infectious agents that can cause an acute diarrhea can be bacterial or viral.  I like to think of the invasive bacterial pathogens (those that cause bloody diarrhea or dysentery) with the acronym “SSCYE” – Salmonella, Shigella, Campylobacter, Yersinia, E. coli.  Other bacteria like Vibrio are frequent causes of watery travelers’ diarrhea and not necessarily enteroinvasive.  In the right clinical context (or even without it) Clostridium difficile needs to be considered.  It rarely produces a bloody diarrheal illness, but can in people with inflammatory bowel diseases or those on anticoagulants.  Viruses like norovirus, rotavirus, and other enteroviruses may cause an acute, self-limited, usually non-bloody diarrhea.  Parasitic infections often produce a longer duration of symptoms, but these can include non-invasive pathogens like Giardia lamblia and invasive pathogens like Entamoeba histolytica.  Giardia is typically transmitted in water from lakes/wells in rural areas.

-Not all proven infectious diarrheas need to be treated.  Entamoeba histolytica diarrhea always needs to be treated.  Bacterial infections like Campylobacter in this case are often self limited.  Reasons for treatment would include prolonged or non-resolving symptoms, systemic symptoms like fever and general malaise, bacteremia as in this case, immunocompromise, or significant other medical comorbidities.

-We spoke briefly about radiation-induced colitis.  Radiation forms part of the management of tethered bowel structures (essentially rectal cancer) and can cause diarrhea and enteritis.  This is typically when small bowel or large bowel are in the radiation field.  The symptoms may start several weeks following radiation therapy and may persist for months.

Further Reading:

Aranda-Michel, J., & Giannella, R. A. (1999). Acute diarrhea: a practical review. The American journal of medicine, 106(6), 670-676.