An Outbreak ofEscherichia coliO157:H7 Infections Associated with Leaf Lettuce Consumption

Abstract

In July 1995, 40 Montana residents were identified with laboratory-confirmed Escherichia coli O157:H7 infection; 52 residents had bloody diarrhea without laboratory confirmation. The median age of those with laboratory-confirmed cases was 42 years (range, 4- 86); 58% were female. Thirteen patients were hospitalized, and 1 developed hemolytic-uremic syndrome. A case-control study showed that 19 (70%) of 27 patients but only 8 (17%) of 46 controls reported eating purchased (not home-grown) leaf lettuce before illness (matched odds ratio, 25.3; 95% confidence interval, 3.9-1065.6). Pulsed-field gel electrophoresis identified a common strain among 22 of 23 isolates tested. Implicated lettuce was traced to two sources: a local Montana farm and six farms in Washington State that shipped under the same label. This outbreak highlights the increasing importance of fresh produce as a vehicle in foodborne illness. Sanitary growing and handling procedures are necessary to prevent these infections.

Differential Binding of Escherichia coli O157:H7 to Alfalfa, Human Epithelial Cells, and Plastic Is Mediated by a Variety of Surface Structures

“…In pediatric and elderly patients, the diarrhea caused by this strain can be fatal due to acute kidney failure (hemolytic-uremic syndrome) (reviewed in reference 31). Although cattle are known to be a reservoir of E. coli O157:H7 (9, 51) and contaminated undercooked beef has been most frequently implicated as a vehicle for pathogen transmission (15), the organism has also been associated with unexpected vehicles of transmission, such as alfalfa sprouts (5), radish sprouts (20), lettuce (1), and unpasteurized apple juice (10). E. coli O157:H7 contamination of fruits and vegetables is a concern in the United States, and its presence in a variety of food products suggests that this pathogen has the ability to express one or more adhesive structures which allow binding to surfaces of many different types of food.…”

Escherichia Coli O157:h7 in Food With Health-Related Risks

“…Common vehicles of the disease noted were fruits and vegetables such as green-based salads, potatoes, lettuce, unspecified fruits, and sprouts (Doyle & Erickson, 2008). Among the reported outbreaks, lettuce was the single most frequently mentioned produce (Ackers et al, 1998;López-Gálvez et al, 2009). Ackers et al (1998) found 70% of patients in 40 Montana residents were infected with E. coli O157:H7 due to the consumption of purchased leaf lettuce.…”

Behavior and changes in cell morphology ofEscherichia coliO157:H7 in liquid medium and skim milk in the presence of caffeine

“…E. coli O157:H7 has been implicated in outbreaks from a variety of foods including raw milk, undercooked ground beef, fermented meat, and lettuce (Ackers et al, 1998;Armstrong, Hollingsworth, & Morris, 1996;Hancock, Besser, Rice, Herriott, & Tarr, 1997;Mao, Doyle, & Chen, 2001). Milk contamination occurs usually during milking, although it is possible during storage and transportation.…”