Hogenauer et al identified cases of antibiotic-associated hemorrhagic colitis caused by cytotoxin-producing strains of Klebsiella oxytoca. This organism should be considered in a patient with pseudomembranous enterocolitis but no evidence for Clostridium difficile. The authors are from the Medical University of Graz in Austria.

Clinical features:

(1) The typical patient is relatively young and healthy.

(2) The patient has a history of recent antibiotic therapy (typically a penicillin derivative) and/or NSAID therapy prior to onset of diarrhea.

(3) The patient develops a hemorrhagic colitis with abdominal cramping and bloody diarrhea.

(4) Colonoscopy shows colitis that is right-side predominant and rectal sparing. No pseudomembrane is seen.

(5) The patient often responds to discontinuing antibiotic therapy and/or NSAIDS.


Laboratory features:

(1) All tests for Clostridium difficile are negative.

(2) Stool cultures are positive for Klebsiella oxytoca.

(3) Cytotoxin is present in the stool.

(4) The patient has signs of inflammation with leukocytosis and an elevated C-reactive protein.

(5) Susceptibility studies show the Klebsiella strain to be resistant to the antibiotic being administered.


The diagnosis of colitis due to Klebsiella oxytoca requires exclusion of other causes of colitis. including ischemic colitis and enterotoxic E. coli.

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