A case of bloody diarrhea

Today we discussed a case of bloody diarrhea here are some pearls:
1) Definition:

• Bloody Diarrhea = Colitis
• Triad of bloody diarrhea, lower abdominal pain and fever = "Dyssentry"

2) Etiology:

• Infectious: Salmonella, Shigella, Yersinia, Campylobacter, C. difficile (though rare), E. coli (enterohemorrhagic O157:H7), CMV in immunocompromised hosts. The most common causes in Toronto would be campylobacter
• Ischemic: Embolic (a. fib, cardiogenic emboli), mesenteric vein thrombosis, aortoiliac bypass, cardiopulmonary bypass.
• Inflammatory: Inflammatory bowel disease, vasculitis of the gut
• Radiation colitis

3) History:

• Exposure history: 
• Travel/sick contacts
• Food: raw beef, pork, poultry, alfalfa sprouts (E.coli), rice (B. cereus), unpasteurized dairy
• Timing of onset: less than 6hrs likely from pre-formed toxin, 8-16h think clostridium, more than 16hrs think viral or bacterial infection, if starts as diarrhea and progresses to h/a, myalgias, think listeria (especially in pregnant women)
• Medications: recent abx
• Recent hospitalizations
• Hx of IBD, radiation, immunosuppression
• Extra-intestinal manifestations of IBD
• Sexual hx

4) Diagnosis:

• Stool C + S, C. diff PCR - very sensitive and specific
• Stool O + P - not very cost effective, but reasonable in immunocompromised patients, community outbreaks of giardia or cryptosporidium, chronic diarrhea.
• Stool leukocytes - not very helpful

5) Treatment:

• Supportive!
• IV hydration, replete electrolytes (patients often have Non-Anion Gap Metabolic Acidosis initially)
• Should you treat with Antibiotics?
• Impact is modest: Decreases duration of symptoms by several days
• Consider treatment in people at risk for complications: elderly, diabetics, cirrhotics, immunocompromised
• Antibiotics are indicated for ETEC (fluoroquinolone), C. diff (metronidazole), Salmonella (flouroquinolone). Abx can also be used for severe campylobacter (macrolides or flouroquinolone)
• See the following link for Utility of antibiotics in diarrhea
• HUS: caused by the shiga toxin from E.coli O157:H7 characterized by bloody diarrhea, MAHA, thrombocytopenia, acute renal failure +/- neurologic symptoms. Antibiotics have been shown to prolong diarrhea and lead to worse outcomes. Prognosis is better than TTP.