As the recent U.S. outbreak of E. coli infections caused by contaminated spinach demonstrates, the safety of the food we eat cannot be taken for granted. Two studies in the Nov. 1 issue of The Journal of Infectious Diseases, now available online, further illustrate the point, one adding a new bacterial culprit to the mix and the other showing that use of antibiotics as growth promoters in livestock increases the risk of antibiotic resistance in humans.
In one study, investigators led by Katri Jalava, DVM, of the Finnish National Public Health Institute, and J. Pekka Nuorti, MD, DSc, of the National Centers for Disease Control and Prevention, traced an outbreak of Yersinia pseudotuberculosis infection among children in a Finnish town to carrots grown on a single farm. An epidemiologic investigation linked illness to eating raw carrots. Laboratory tests confirmed that the bacteria in infected children's stool samples were indistinguishable from the bacteria isolated from the farm.
The authors noted that this marked the first time that the bacterium had been recovered from an epidemiologically implicated source of food-borne illness. They pointed out that it is well known as a pathogen in wild mammals, and that the farm stored the carrots in a barn in open containers for months. "A combination of direct contact with wildlife feces during storage and cross-contamination during washing and peeling," they concluded, "are the most likely contributing factors." To prevent such outbreaks, "regulations addressing the production, storage and shipping conditions for fresh produce are needed."
In the other study, Edward A. Belongia, MD, and colleagues at the Marshfield Clinic Research Foundation, Marshfield, Wis., and elsewhere examined poultry exposure as a risk factor for antibiotic resistance by Enterococcus faecium, a gut bacterium that is an increasing cause of hospital infections. A drug combination called quinupristin-dalfopristin, also
Contact: Steve Baragona
Infectious Diseases Society of America