Diagnosis
Case 71
【Progress】Stool culture tests of both two patients revealed positive vero-toxin test and positive Escherichia coli O157. They received antibiotics for a week and were discharged with a healthy condition.
【Discussion】
Hundred strains of Escherichia coli (E. coli) habit in the intestine of a healthy human and help maintain the balance of normal flora against harmful bacteria and produce some vitamins. However, several strains of E. coli, a particular strain of E. coli O157 cause severe colitis and bloody diarrhea. The delay of appropriate treatment for E. coli O157 increases a risk of hemolytic uremic syndrome which is a potential fatal complication (1, 2). Hemolytic uremic syndrome is caused by verotoxin secreted from E. coli O157 which destruct vascular endothelial cells, inducing hemolysis of red blood cells, thrombocytopenia, and elevation of FDP, leading to acute renal failure (1, 2). Fortunately, in our two cases, although verotoxin test was positive, there was no evidence of hematuria and no elevation of creatinin and no decrease of red blood cells and thrombocytes.
E. coli O157 is found in cattle of pig and cow and infected to human by not only raw meats of cattle but also raw vegetable, milk and surface water frequently visited by animals. The outbreak of E. coli O157 occurred in Sakai city in 2012 was caused by radish sprouts. Of the 9492 patients, 121 patients were caught in hemolytic uremic syndrome and 3 patients died (3). In our both patients, they ate row cow liver at the same restaurant on the same day. They did not fall in hemolytic uremia but did recover during hospitalization.
E Coli O157, Salmonella, Campylobacter and Yersinia are listed as the species of the common infectious colitis (4). One of the common CT findings of the infectious colitis is the mural thickening of ascending colon: a three-layer-structure which composed of mucosal layer, edematous submucosal layer and smooth muscle layer (2, 4-11). The CT findings of three-layer-structure of ascending colon are non-specific (4-8) in infectious colitis but specific characters of the infectious colitis are known. For examples, E coli O157 infection often induces peritonitis with the existence of dirty adipose tissue, ascitis and mesenteric swollen lymphnodes (7, 8). Shiga toxin producing E coli O104 affects the descending colon with upstream distension of the transverse/ascending colon and differs from other types of colitis (8). Yersina entrocolotics often induces enlarged mesenteric lymphnodes and mural thickening in terminal ileum including appendix which should be differentiated from appendicitis (9, 10). In our both cases, CT showed three-layer edematous thickening of ascending and transverse colon with dirty adipose tissue and small fluid retention in the para-colic gutter, whose findings were not experienced in CT findings of patient with Salmonella, Campylobacter and Yersinia in our hospital.
【Summary】
We present two cases with infectious colitis of E coli O157. They suffered from bloody diarrhea and ate raw cow liver at the same restaurant on the same day of several days ago. CT showed the three-layer edematous wall thickening of ascending colon and transverse colon with dirty adipose tissue and small fluid retention at para-colic gutter. We should keep in mind that submucosal edema is the main component of the three layers which is non-specific findings in infectious colitis but dirty adipose tissue and para-colic fluid retention are specific findings in E coli O157 colitis. In the literature, pyelonephritis due to hemolytic uremic syndrome with infectious colitis is specific findings in E coli 157 colitis. But in our cases, hemolytic uremic syndrome was not found, which was reported to occur 1.3% (121/9492) in Sakai outbreak of E coli 157 colitis in 2012.
【References】
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3. 堺市学童集団下痢症」の概要 http://www.city.sakai.lg.jp/kenko/shokuhineisei/shokuchudokuyobo/hokokusho/index.html
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9. Antonopoulos P et al. An emergency diagnostic dilemma: a case of Yersinia enterocolitica colitis mimicking acute appendicitis in a beta-thalassemia major patient: the role of CT and literature review. Emerg Radiol. 2008 Mar;15(2):123-6. Epub 2007 Jul 10.
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2017.9.13