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Hemorrhagic Proctosigmoiditis and Blastocystis hominis
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TO THE EDITOR:
Carrascosa and colleagues recently reported a case of hemorrhagic proctosigmoiditis in the setting of documented Blastocystis hominis infection [1]. They suggest that their case provides further evidence to support the pathogenicity of B. hominis and the idea that B. hominis should be considered a possible cause of hemorrhagic colitis in both immunocompetent and immunocompromised patients. Although I agree with their cautious conclusion, several points about the case merit comment.
First, the authors mention that the patient's stool was not examined for Shiga-like toxins. I assume that they are alluding to the fact that enterohemorrhagic infection with Escherichia coli (E. coli O157:H7) was not excluded. Because E. coli O157:H7 is a common cause of hemorrhagic colitis [2], the authors' failure to exclude infection with this organism weakens their conclusion.
Second, the authors state that the results of mesenteric and celiac arteriography were normal. I assume that the authors believe that these results rule out the possibility of a diagnosis of ischemia-related disease; unfortunately, this is not the case. Although many conditions have been associated with colonic ischemia, no precipitating factor is identified in most patients [3]. The episodes are considered to be spontaneous and occur without major vessel occlusion (that is, they are events of “nonocclusive ischemia”) [4]. Therefore, normal results of mesenteric arteriography do not exclude the possibility that the patient's hemorrhagic colitis has an ischemic cause. Although rectal involvement (as in Carrascosa and colleagues' patient) is unusual in ischemic colitis, information on the proximal extent of disease (shown by colonoscopy) is not available. If the patient's colitis was segmental, as the result of barium enema suggests, an ischemic cause would still deserve consideration. The above tenets should temper the authors' conclusion about the possible role of B. hominis in hemorrhagic colitis.
Joseph Carl Yarze, MD
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
