Outbreak of Shiga Toxin-Producing Escherichia coli (STEC) O157:H7 Associated with Romaine Lettuce Consumption, 2011

• Type of Material: Article
• Authors: Rachel B. Slayton, Centers for Disease Control and Prevention; George Turabelidze, Missouri Department of Health and Senior Service; Sarah D. Bennett, Centers for Disease Control and Prevention; Colin A. Schwensohn, Centers for Disease Control and Prevention; Anna Yaffee, Emory University; Faisal Khan, St Louis City Department of Health; Cindy Butler, Missouri Department of Health and Senior Service; Eija Trees, Centers for Disease Control and Prevention; Tracy L. Ayers, Centers for Disease Control and Prevention; Marjorie L. Davis, United States Food and Drug Administration; Alison S. Laufer, Centers for Disease Control and Prevention; Stephen Gladbach, Missouri Department of Health and Senior Service; Ian Williams, Centers for Disease Control and Prevention; Laura B. Gieraltowski, Centers for Disease Control and Prevention
• Language: English
• Date: 2013-02-04
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: This is an open-access article, free of all copyright
• License: Creative Commons Creative Commons CC0 1.0 Universal
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0055300
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 8
• Issue: 2
• Start Page: e55300
• End Page: e55300
• Grant/Funding Information: The authors have no support or funding to report.
• Keywords: Science & Technology - Other Topics; FOODBORNE ILLNESS; Science & Technology; UNITED-STATES; O157-H7; CALIFORNIA; Multidisciplinary Sciences
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Nutrition

Abstract

Background: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is the causal agent for more than 96,000 cases of diarrheal illness and 3,200 infection-attributable hospitalizations annually in the United States. Materials and Methods: We defined a confirmed case as a compatible illness in a person with the outbreak strain during 10/07/2011-11/30/2011. Investigation included hypothesis generation, a case-control study utilizing geographically-matched controls, and a case series investigation. Environmental inspections and tracebacks were conducted. Results: We identified 58 cases in 10 states; 67% were hospitalized and 6.4% developed hemolytic uremic syndrome. Any romaine consumption was significantly associated with illness (matched Odds Ratio (mOR) = 10.0, 95% Confidence Interval (CI) = 2.1-97.0). Grocery Store Chain A salad bar was significantly associated with illness (mOR = 18.9, 95% CI = 4.5-176.8). Two separate traceback investigations for romaine lettuce converged on Farm A. Case series results indicate that cases (64.9%) were more likely than the FoodNet population (47%) to eat romaine lettuce (p-value = 0.013); 61.3% of cases reported consuming romaine lettuce from the Grocery Store Chain A salad bar. Conclusions: This multistate outbreak of STEC O157:H7 infections was associated with consumption of romaine lettuce. Traceback analysis determined that a single common lot of romaine lettuce harvested from Farm A was used to supply Grocery Store Chain A and a university campus linked to a case with the outbreak strain. An investigation at Farm A did not identify the source of contamination. Improved ability to trace produce from the growing fields to the point of consumption will allow more timely prevention and control measures to be implemented.