title: Escherichia coli O157:H7 Outbreak Associated with Restaurant Beef Grinding.
abstract: Escherichia coli O157:H7 is a common cause of foodborne illness in the United States. Beef ground at establishments regulated by the U.S. Department of Agriculture, Food Safety and Inspection Service is routinely tested for E. coli O157:H7. Prior to December 2013, boxed beef product (wholesale cuts of beef, such as beef loin, packaged into bags and boxed for shipping) was not always tested for this pathogen. Downstream processors or retailers may grind the product; and, if the ground beef is not cooked to the recommended temperature, pathogens on the exterior of the beef introduced to the interior through grinding may survive. On 18 October 2013, the Allegheny County Health Department identified two E. coli O157:H7 cases, both of whom were food handlers at restaurant A, a restaurant that ground locally produced boxed beef for hamburgers on site. Case finding was conducted through public messaging, employee surveys, and disease surveillance. All potential cases were interviewed using a standard questionnaire. A confirmed case was defined as laboratory-confirmed E. coli O157:H7 with exposure to restaurant A. A probable case was defined as a patient with compatible symptoms and exposure to restaurant A but without laboratory confirmation. All human and food isolates were characterized by pulsed-field gel electrophoresis and multilocus variable-number tandem repeat analysis. The analysis identified 14 confirmed and 10 probable cases of E. coli; 18 nonintact ground beef samples tested positive for E. coli O157:H7. Nine confirmed cases were restaurant A employees. All confirmed cases recalled eating a restaurant A hamburger in the 10 days before illness onset; most cases reported consuming medium to rare hamburgers. Multiple pulsed-field gel electrophoresis and multilocus variable-number tandem repeat analysis patterns were identified among both the human and ground beef isolates, and the patient isolates matched those found in ground beef samples. Restaurant A voluntarily closed for 1.5 days, changed beef suppliers, ceased grinding beef in-house, and has had no new cases since reopening.
authors.affiliation: Office of Epidemiology and Biostatistics, Allegheny County Health Department, 542 Fourth Avenue, Pittsburgh, Pennsylvania 15219, USA. ltorso@achd.net.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Torso
authors.affiliation: Office of Epidemiology and Biostatistics, Allegheny County Health Department, 542 Fourth Avenue, Pittsburgh, Pennsylvania 15219, USA.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Voorhees
authors.affiliation: Office of Epidemiology and Biostatistics, Allegheny County Health Department, 542 Fourth Avenue, Pittsburgh, Pennsylvania 15219, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Forest
authors.affiliation: Office of Epidemiology and Biostatistics, Allegheny County Health Department, 542 Fourth Avenue, Pittsburgh, Pennsylvania 15219, USA; Public Health Associates Program, Centers for Disease Control and Prevention, 4770 Buford Highway MS E-85, Chamblee, Georgia 30341, USA.
authors.forename: Andrew Z
authors.initials: AZ
authors.lastname: Gordon
authors.affiliation: Infectious Disease Program, Allegheny County Health Department, 3441 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Silvestri
authors.affiliation: Food Safety and Inspection Service, U.S. Department of Agriculture, 1600 Clifton Road, Atlanta, Georgia 30329, USA.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Kissler
authors.affiliation: Infectious Disease Epidemiology Research Unit, Departments of Epidemiology and Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Schlackman
authors.affiliation: Pennsylvania Department of Health, Bureau of Laboratories, 110 Pickering Way, Exton, Pennsylvania 19341-1310, USA.
authors.forename: Carol H
authors.initials: CH
authors.lastname: Sandt
authors.affiliation: Food Safety and Inspection Service, U.S. Department of Agriculture, 1000 Liberty Avenue, Suite 809, Pittsburgh, Pennsylvania 15222, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Toma
authors.affiliation: Food Safety and Inspection Service, U.S. Department of Agriculture, 123 Hazle Street, Wilkes Barre, Pennsylvania 18702, USA, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Bachert
authors.affiliation: Office of Epidemiology and Biostatistics, Allegheny County Health Department, 542 Fourth Avenue, Pittsburgh, Pennsylvania 15219, USA.
authors.forename: Kristen J
authors.initials: KJ
authors.lastname: Mertz
authors.affiliation: Infectious Disease Epidemiology Research Unit, Departments of Epidemiology and Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
mesh_terms: D000818:Animals; D002417:Cattle; D003296:Cooking / Q000379:methods; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics; D005511:Food Handling / Q000379:methods*; D059022:Food Safety; D005517:Foodborne Diseases / Q000453:epidemiology; D006801:Humans; D018598:Minisatellite Repeats; D000069466:Red Meat / Q000382:microbiology*; D012147:Restaurants; D011795:Surveys and Questionnaires; D020080:Tandem Repeat Sequences; D013696:Temperature; D014481:United States