Renal Impairment Linked to E. coli Infection

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MONTREAL—A decade after contracting acute diarrheal illness from infection with Escherichia coli 0157:H7, individuals are at increased risk for definite renal impairment with microalbuminuria, hypertension, and cardiovascular events compared with individuals not infected with the pathogen.

These were among the key findings of the prospective, community-based Walkerton Health Study, which were presented at the Canadian Society of Nephrology's 2010 annual meeting.

“These findings underline the need to follow up and, where indicated, treat individual cases of food or water poisoning by E. coli 0157:H7 to prevent or reduce silent progressive vascular injury,” said lead investigator William Clark, MD, Professor of Medicine at the University of Western Ontario in London and Director of Apheresis Services at the London Health Sciences Centre.

Dr. Clark and his colleagues followed residents of Walkerton, Ont., and the surrounding area who, for three days in May 2000, were exposed to 0157:H7 after farm runoff contaminated the town's water supply. More than 2,300 people from among the approximately 4,500 area residents experienced bloody diarrhea, gastrointestinal infections, and other symptoms after being infected. Seven died.

The team examined medical records that included laboratory test results and family doctors' notes from the 1,977 adult patients who experienced gastroenteritis and a control group of 910 who did not get sick. The investigators excluded all those who were under 18 and/or had evidence of pre-outbreak disease.

Individuals exposed to E. coli 0157:H7 who had diarrhea-associated gastroenteritis had a 3.6 times increased odds of developing definite renal impairment with microalbuminuria and 2.5 times increased odds of experiencing cardiovascular events such as myocardial infarction, stroke, or congestive heart failure They also had a 33% greater risk of developing hypertension within the next 10 years than did those who did not have gastroenteritis.

The team also performed a more stringent analysis by excluding all whose initial detection of hypertension, definite renal impairment, and cardiovascular disease had occurred at the first study visit. The goal was to eliminate potential pre-existing undetected disease.

“This resulted in an increase in the hazard or risk ratios—which means the increased risks we detected were an underestimate of the potential and thus a conservative estimate of the risk following exposure to E. coli 0157:H7,” Dr. Clark said. “The overall message is the need for simple follow-up for those who develop gastroenteritis due to E. coli 0157:H7 in order to provide preventive therapy, which is what we did in Walkerton.”

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