Plasmids have an important role in the pathogenicity of certain bacterial species, and Escherichia coli provides the most complete example of the relationship involved. Enterotoxigenic strains of E. coli, in addition to producing heat-stable and/or heat-labile enterotoxins, may also produce a haemolysin and fimbriate cell surface antigens which facilitate the adherence of the bacterial cell to the mucosa of the small bowel. Numerous studies have shown that these properties are plasmid-mediated and that the plasmids act in concert to confer on the host bacterium the ability to produce enteric disease in man and in animals. Moreover, studies with invasive strains of E. coli have shown that the Col V plasmid, which codes for the synthesis of colicin V, significantly enhances the pathogenicity of its host bacterium. Although the relationship between Col V plasmids and virulence is unclear, reports indicate that Col V-containing strains of E. coli are better able to survive in the alimentary tract and that colicine V itself inhibits macrophage function. It is probable that bacterial virulence is a complex phenomenon involving both chromosomal and plasmid genes. We describe here a virulence plasmid which mediates tissue invasiveness in human pathogenic strains of Yersinia enterocolitica.

This is the first reported STEC outbreak associated with consuming ready-to-bake commercial prepackaged cookie dough. Despite instructions to bake brand A cookie dough before eating, case patients consumed the product uncooked. Manufacturers should consider formulating ready-to-bake commercial prepackaged cookie dough to be as safe as a ready-to-eat product. More effective consumer education about the risks of eating unbaked cookie dough is needed.

This outbreak was caused by commercially produced, internationally distributed carrot juice that was contaminated with botulinum toxin. When toxemia persists, treatment for botulism should be considered even if diagnosed weeks after illness onset. The implicated pasteurized carrot juice had no barriers to growth of C. botulinum other than refrigeration; additional protective measures for carrot juice are needed to prevent future outbreaks. The US Food and Drug Administration has since issued industry guidance to reduce the risk of C. botulinum intoxication from low-acid refrigerated juices.