On November 17, 2012 the Centers for Disease Control and Prevention (CDC) announced that several East coast states were investigating an outbreak of E. coli O157:H7.  At that time a total of 28 patients had been reported by 5 states.  Public health investigators used DNA “fingerprints” of E. coli bacteria obtained through diagnostic testing with pulsed-field gel electrophoresis (PFGE) to identify outbreak-associated patients.  The outbreak strain was unusual and rarely seen in PulseNet, the national subtyping network that performs molecular surveillance of foodborne infections.  The strain, identified as EXHX01.3183/EXHA26.1168, had only been seen 7 times prior to this outbreak.

State public health officials interviewed ill persons to obtain information about foods they might have eaten and other exposures in the week before illness.  At the close of the investigation, 33 ill persons infected with the outbreak strain EXHX01.3183/EXHA26.1168 had been reported from five states:  Connecticut (n=2), Massachusetts (n=3), New York (n=26), Pennsylvania (n=1) and Virginia (n=1).  Among persons for whom information was available, illness onset dates ranged from October 18, 2012 to November 12, 2012.  Ill persons ranged in age from 4 years to 66 years.  Sixty-three percent of ill persons were female.  Among 28 ill persons with available information, 13 (46%) were hospitalized.  Two ill persons developed hemolytic uremic syndrome (HUS).  No deaths were reported.

Epidemiologic, laboratory, and traceback investigations conducted by officials in local, state and federal public health, agriculture, and regulatory agencies linked this outbreak to consumption of pre-packaged leafy greens produced by State Garden of Chelsea, Massachusetts.  Thirty (97%) of 31 ill persons interviewed reported eating pre-packaged leafy greens.  Fifteen (48%) reported eating Wegmans brand Organic Spinach and Spring Mix blend in the week before become ill.  In total, 25 (81%) of 31 ill persons for whom information was available reported eating a variety of different brands of pre-packaged leafy greens produced by State Garden.

Testing conducted by the New York Department of Health Wadsworth Center Laboratories isolated the outbreak strain of E. coli O157:H7 from four leftover packages of Wegmans brand Organic Spinach and Spring Mix blend collected from four ill persons’ homes.[1]

Traceback investigations of pre-packaged leafy greens purchased by ill persons identified State Garden as a common producer.  On November 2, 2012, Wegmans voluntarily recalled its 5-ounce and 11-ounce clamshell packages of Organic Spinach and Spring Mix blend, a product produced by State Garden.[2]  State Garden issued a consumer advisory regarding the product packaged on October 12 and 13, 2012.[3]

E. coli outbreaks associated with lettuce, specifically the “pre-washed” and “ready-to-eat” varieties, are by no means a new phenomenon.  In fact, the frequency with which this country’s fresh produce consuming public has been hit by outbreaks of pathogenic bacteria is astonishing. Here are just a sample of E. coli outbreaks based on information gathered by the Center for Science in the Public Interest, Kansas State University and the Centers for Disease Control and Prevention: