Treatment of dysentery can be complex, especially when the causative agent is unknown.  Diarrhea of small bowel origin is typically large volume and non-bloody, such as in Traveler’s Diarrhea.  Diarrhea of large bowel origin is small volume and associated with fever, tenesmus, and abdominal pain, and more commonly associated with dysentery, or blood and mucous in the stool. 

Infectious causes of diarrhea are common and include viral origin, bacteria, protozoa, among others.  Most viruses affect the small bowel and do not cause dysentery in immunocompetent hosts.  Protozoa, such as Entamoeba Histolytica, or Amebiasis, should be considered in international travelers with prolonged stay in a third-world country or in Men who have sex with Men. 

Bacterial causes of dysentery are common.  Treatment of dysentery can be more complex if the organism is not yet known, such as when traveling internationally, or when stool cultures are pending and decisions have to be made.  If the patient has fever 101.3 or higher, bloody diarrhea, severe abdominal pain, hypovolemia, and/or greater than 6 diarrheal stools per day, treatment should be considered.  If the patient is an infant, or greater than 70 years old, or immunocompromised, or the patient appears toxic, treatment should be strongly considered.

Treatment with Azithromycin 500 mg po daily x 3 days, is often considered first line.  If the patient has bloody diarrhea without fever, and the causative organism is unknown, treatment may be withheld, to avoid an increased risk of Hemolytic Uremic Syndrome caused by Shiga-toxin producing E. coli O157:H7.  If the patient is high risk, as above, benefits of treatment may outweigh risks and should be individualized.  In addition, always question patients with diarrhea for recent antibiotic use over the last 3 months to keep in mind clostridium difficile.