antibiotic treatment of escherichia coli o157 infection and the risk of hemolytic uremic syndrome minnesota background infection with escherichia coli o157 o157 can lead to the development of hemolytic uremic syndrome hus treating o157 infections with antibiotics is a possible risk factor for hus development however previous studies evaluating this relationship have yielded conflicting results the objective of this study was to further evaluate this issuemethods an agematched casecase comparison study comprising minnesota residents less than 20 years of age with cultureconfirmed o157 infection who did n 66 or did not n 129 subsequently develop hus was conducted subjects were identified through statewide surveillance activities by the minnesota department of health from 1996 to 2002results overall antibiotic treatment was not associated with the development of hus selfreported vomiting and female gender were significantly associated with the development of hus after adjustment for illness severity and gender subjects who developed hus were more likely to have been treated only with bactericidal antibiotics within the first 3 days adjusted matched odds ratio or 124 95 confidence interval ci 141103 or within the first 7 days or 180 95 ci 191709 after the onset of diarrhea in particular the use of lactams penicillins or cephalosporins in the first 3 days after diarrhea onset was also significant after adjustment or 113 95 ci 121067conclusions individuals infected with o157 infection presenting with a more severe illness were at an increased risk of developing hus the use of bactericidal antibiotics particularly lactams to treat o157 infection was associated with the subsequent development of hus