Official websites use. Share sensitive information only on official, secure websites. Corresponding author. Phone: Fax: E-mail: pfeng cfsan. Produce isolates of the Escherichia coli Ont:H52 serotype carried Shiga toxin 1 and stable toxin genes but only expressed Stx1.
All Ont:H52 strains had identical single nucleotide polymorphism profiles that are suggestive of a unique clonal group. Using a multiplex PCR assay S. Monday and P. Feng, unpublished data , two E. Since pathogenic E. In this study, these strains were characterized by phenotypic, serologic, and genetic assays as well as by molecular subtyping to determine their genetic relatedness to other pathogenic E.
The MDP strains were streak plated onto various selective and differential media and confirmed to be pure cultures. These strains had typical E. Agarose gel electrophoresis of PCR products Fig. The serotype and virulence factor information was previously published or determined in this study. Although genetic evidence showed the presence of both the ST and Stx1 genes in MDP strains, it was uncertain whether the genes were actually expressed.
Competitive immunoassay; values above 0. OD , optical density at nm. These MDP strains have identical traits but were isolated from different produce from different localities see Table 3. Strain TW, obtained from the CDC, was isolated in from an month-old patient with diarrhea in Virginia who was also infected with rotavirus, while MDP was isolated in from cantaloupe sampled in Maryland. Despite the proximity of the two isolation locations, there were no clear associations between these strains.
Since cilantro is an often-used ingredient in these types of restaurants, it seems beyond coincidence and possible that this strain may have been the causative agent of illness. Opt, optimization; Tol, tolerance; H, height; S, surface. Many of the virulence genes in E. Likewise, the stx genes are encoded by bacteriophages, which can be spontaneously induced during subculture 4 , 8 and may, theoretically, infect other bacteria.
