A Prolonged Outbreak ofEscherichia coliO157:H7 Infections Caused by Commercially Distributed Raw Milk

Abstract

A protracted outbreak of Escherichia coli O157:H7 infections was caused by consumption of unpasteurized ("raw") milk sold at Oregon grocery stores. Although it never caused a noticeable increase in reported infections, the outbreak was recognized because of routine follow-up interviews. Six of 16 Portland-area cases reported between December 1992 and April 1993 involved people who drank raw milk from dairy A. By pulsed-field gel electrophoresis (PFGE), E. coli O157:H7 isolates from these cases and from the dairy A herd were homologous (initially, 4 of 132 animals were E. coli O157:H7-positive). Despite public warnings, new labeling requirements, and increased monitoring of dairy A, retail sales and dairy-associated infections continued until June 1994 (a total of 14 primary cases). Seven distinguishable PFGE patterns in 3 homology groups were identified among patient and dairy herd E. coli O157:H7 isolates. Without restrictions on distribution, E. coli O157:H7 outbreaks caused by raw milk consumption can continue indefinitely, with infections occurring intermittently and unpredictably.

PulseNet: The Molecular Subtyping Network for Foodborne Bacterial Disease Surveillance, United States

“…The observation that isolates from two or more persons have indistinguishable PFGE patterns should not be considered proof that the persons had a common exposure, merely that the isolates in question share a common ancestry. Moreover, outbreaks can be caused by more than one subtype, so that differences in PFGE pattern alone cannot prove that isolates did not have a common source (24,25).…”

Genome-Wide Transposon Mutagenesis Reveals a Role for pO157 Genes in Biofilm Development in Escherichia coli O157:H7 EDL933

“…Since then, this organism has emerged as a major cause of food-borne illness in countries around the world, including the United States (49), Europe (17,18,24,36), Japan (39), and Australia (28). Outbreaks have been associated with a variety of food sources, including ground beef (50), green leafy vegetables (1,41), and nonpasteurized milk (26), and environments such as municipal water and lakes (27,55). Symptoms in infected humans range from mild diarrhea to severe, hemorrhagic colitis, with 5 to 10% of patients developing hemolytic uremic syndrome (HUS), making E. coli O157:H7 one of the leading causes of acute renal failure in children and the elderly (38).…”

Role of Glucose in Enhancing the Temperature-Dependent Growth Inhibition ofEscherichia coliO157:H7 ATCC 43895 by aPseudomonassp

“…The pathogen has been involved in an increasing number of food-borne disease outbreaks linked to the consumption of various foods, including undercooked ground beef (2), unpasteurized milk (12), fresh produce (1), and acidic foods (5). Its survival in acidic foods may be due to acid adaptation (14) or to the high acid tolerance of some strains (3,4).…”