E. coli Diarrheal Illness
Abstract & Commentary
Source: Slutsker L, et al. Escherichia coli 0157:H7 diarrhea in the United States: Clinical and epidemiologic features. Ann Intern Med 1997;126:505-513.
Slutsker and colleagues sought to determine the frequency of isolation of Escherichia coli 0157:H7, as well as the clinical characteristics and the epidemiologic features of such infection, relative to other enteric pathogens among patients with acute diarrheal illness. Study participants included all patients who underwent stool culture for enteric pathogens in 10 geographically diverse hospitals in the United States over a two-year period ending in 1992. Of 30,463 patients included in the study, E. coli 0157:H7 was isolated in 118 (0.39%) cases. The frequency of isolation, greater in the warm months, was higher at northern sites (0.57%) compared to southern locales (0.13%). With regard to age, two patient groups suffered the highest rates of isolation: 5-9-year-olds (0.90%) and 50-59- year-olds (0.89%). Patients with this form of diarrheal illness more often complained of bloody diarrhea, manifested abdominal tenderness, normothermia, and visibly bloody stool on examination. Patients also demonstrated a serum WBC count of greater than 10 ´ 109/liter. One-third of patients ultimately found to have E. coli 0157:H7 in the stool did not have gross blood found on examination, although approximately 90% of patients had noted previously bloody stools. Slutsker et al also note that fecal leukocytes were frequently present in patients with E. coli 0157:H7-related illness.
COMMENT BY WILLIAM BRADY, MD
E. coli 0157:H7 has been implicated with increasing frequency as a cause of bloody diarrhea in the United States. Unfortunately, the microbiologic diagnosis of this particular illness requires additional techniques to those performed in the typical analysis of "stool for enteric pathogens" testingtechniques frequently not used in laboratories unless specifically requested. This E. coli-mediated gastrointestinal malady is a significant medical issue not only because of the actual diarrheal illness that it causes, but also because of the potential of developing hemolytic uremic syndrome (HUS)E. coli 0157:H7 is a major cause of HUS among children in this country.
The work by Slutsker et al raises the level of awareness of ED physicians for the potential of E. coli 0157:H7-mediated diarrhea; Slutsker et al also describe the likely host of such infection, and they suggest certain high-yield criteria for stool culture. This report stresses the fact that E. coli 0157:H7 is not an infrequent pathogen of diarrheal illness, and it may surpass other "typical" enteric pathogens in northern areas of the country, as well as in children and older adults. The finding of fecal leukocytes should not dissuade the clinician from consideration of this form of E. coli 0157:H7 as a potential pathogen. They also suggest that the use of the patient report of bloody diarrhea and visible blood in the stool noted at examinationin combinationare high- yield criteria for the eventual isolation of E. coli from the stool. Slutsker et al conclude that this subtype of E coli should be considered as a potential pathogen in all patientsnot just childrenwho present with bloody diarrhea. When considering E. coli 0157:H7 as a potential pathogen, the clinician should inform the clinical laboratory of this suspicion, so that proper microbiologic technique may be applied. Unfortunately, Slutsker et al did not collect data on the incidence of associated HUS or other sequelae.
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