Multistate outbreak of Escherichia coli O145 infections associated with romaine lettuce consumption, 2010.

Non-O157 Shiga toxin-producing Escherichia coli (STEC) can cause severe illness, including hemolytic uremic syndrome (HUS). STEC O145 is the sixth most commonly reported non-O157 STEC in the United States, although outbreaks have been infrequent. In April and May 2010, we investigated a multistate outbreak of STEC O145 infection. Confirmed cases were STEC O145 infections with isolate pulsed-field gel electrophoresis patterns indistinguishable from those of the outbreak strain. Probable cases were STEC O145 infections or HUS in persons who were epidemiologically linked. Case-control studies were conducted in Michigan and Ohio; food exposures were analyzed at the restaurant, menu, and ingredient level. Environmental inspections were conducted in implicated food establishments, and food samples were collected and tested. To characterize clinical findings associated with infections, we conducted a chart review for case patients who sought medical care. We identified 27 confirmed and 4 probable cases from five states. Of these, 14 (45%) were hospitalized, 3 (10%) developed HUS, and none died. Among two case-control studies conducted, illness was significantly associated with consumption of shredded romaine lettuce in Michigan (odds ratio [OR] = undefined; 95% confidence interval [CI] = 1.6 to undefined) and Ohio (OR = 10.9; 95% CI = 3.1 to 40.5). Samples from an unopened bag of shredded romaine lettuce yielded the predominant outbreak strain. Of 15 case patients included in the chart review, 14 (93%) had diarrhea and abdominal cramps and 11 (73%) developed bloody diarrhea. This report documents the first foodborne outbreak of STEC O145 infections in the United States. Current surveillance efforts focus primarily on E. coli O157 infections; however, non-O157 STEC can cause similar disease and outbreaks, and efforts should be made to identify both O157 and non-O157 STEC infections. Providers should test all patients with bloody diarrhea for both non-O157 and O157 STEC.

Isolation and characterization of Salmonella from broiler carcasses or parts.

A study was conducted to determine and characterize Salmonella contamination on ready-to-cook broilers or parts in the Columbus, OH, metropolitan area. Ten to twelve samples per store were examined, using a whole-carcass rinse method. The Salmonella cultures isolated were tested for resistance to a series of nine drugs and, subsequently, were sent to the National Veterinary Services Laboratory at Ames, IA for serotype identification. Cultures identified as Salmonella were also examined for the presence of plasmids. Salmonella was isolated from one or more samples obtained from 11 of the 12 stores, and from 43% of the 142 samples examined. The serotypes isolated most often were Salmonella hadar, Salmonella heidelberg, and Salmonella johannesburg. Of the 55 cultures tested for drug resistance, 32.7% were sensitive to all nine drugs. The most-common patterns of drug resistance were triple sulfa (41.8% of the cultures) and tetracycline (34.5% of the cultures). Plasmids were found in 41.7% of the 36 cultures analyzed. The results of the present study indicate that the probability is high that carcasses from retail stores will have at least a few drug-resistant Salmonella cells.