A case of bloody diarrhea

Today we discussed a case of bloody diarrhea caused by Enterohemorrhagic E. coli (EHEC), strain O157: H7.

Patients with this infection generally present with bloody diarrhea, mild leukocytosis, abdominal pain, but no fever. This bacteria produces a toxin called the Shiga toxin which can result in the dreaded Hemolytic-uremic syndrome (HUS)- the major systemic complication of EHEC infection. HUS is characterized by the triad of acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia

The treatment of EHEC infection consists of supportive care and monitoring for the development of microangiopathic complications. Administering antibiotic therapy to patients with EHEC is not recommended (Grade 1B- though the evidence is only in children <10).

Here is a review article on the topic.

Escherichia coli O157:H7 and the hemolytic-uremic syndrome.Boyce TG, Swerdlow DL, Griffin PM. N Engl J Med. 1995;333(6):364.

* Romanian greenhouse employees destroy tons of cucumbers for fear of E. coli. In May 2011, a new Shiga toxin-producing EHEC strain, O104:H4, was identified as the cause of an outbreak in Germany and other countries in Europe.

Colitis

Today we discussed the approach to bloody diarrhea. Some things that came up:

Bloody diarrhea implies colitis (of some etiology)
Triad of fever, bloody diarrhea, lower abdo pain defines "dyssentry".

Differential diagnosis:
Infectious colitis: campylobacter, yersinia, samonella, shigella, E. Coli (enterohemorrhagic), C.diff. In immunocompromise: CMV.
Ischemic colitis: seen in patients with severe vascular disease, hypercoagulable states, A-fib
Inflammatory colitis: UC (bloody diarrhea and mucous are hallmark symptoms), Crohn's
Post-radiation colitis

Important history:
travel, food, others with same symptoms, medications, hospitalization, sexual contact, symptoms suggesting IBD (inc. extra-intestinal), fhx, constitutional symptoms, immunosuppression risk factors


Antibiotics in infectious diarrhea:

Most causes do not require (and sometimes are worsened by) antibiotics.

Exceptions where Abx are indicated:
C. Difficile
Shigella (to prevent transmission)
Enterotoxogenic E. coli (ETEC) = "traveller's diarrhea", not 0157 (that is enterohemorrhagic)
Entamoeba histolytica
Giardia
Only in severe cases of yersinia, campylobacter, salmonella

Abx are harmful in
Enterohemorrhagic E. coli (as in Walkerton)

Abx not usually needed for
salmonella, campylobacter (most common causes of infectious colitis). Note that campylobacter is not covered by ciprofloxacin (if need to treat, use macrolide)


Extraintestinal manifestations of IBD

Eyes- uveitis
Skin- eryhtema nodosum, pyoderma gangrenosum
GI- PSC (esp UC), stones
Renal (stones- IBD affects oxalate metabolism by unabsorbed bile salts binding calcium, allowing increased oxalate absorption)
Arthritis- Seronegative, large joint symmetric. Either peripheral, which parallels IBD activity, or axial, which is usually independent of IBD activity


Toxic megacolon

Non-obstructing dilation of the colon.
May occur from infectious etiology as well as IBD.
Clinical: tachycardia, hypotension, fever, volume depletion, altered sensorium.
AXR: greater than 6cm at transverse, thumbprinting (big haustra), pneumatosis coli.


Reference:

Click here for a NEJM review of infectious diarrhea