Abstract
Produce contains high levels of mixed microflora, including coliforms and Escherichia coli, but occasionally pathogens may also be present. Enterotoxigenic E. coli and Shigatoxin-producing E. coli (STEC) have been isolated from various produce types, especially spinach. The presence of STEC in produce is easily detected by PCR for the Shiga toxin (Stx) gene, stx, but this is insufficient for risk analysis. STEC comprises hundreds of serotypes that include known pathogenic serotypes and strains that do not appear to cause severe illness. Moreover, Stx without a binding factor like intimin (encoded by eae) is deemed to be insufficient to cause severe disease. Hence, risk analyses require testing for other virulence or serotype-specific genes. Multiplex PCR enables simultaneous testing of many targets, but, in a mixed flora sample, not all targets detected may be coming from the same cell. The need to isolate and confirm STEC in produce is critical, but it is time- and labor-intensive due to the complexity of the group. Studies showed that only a handful of STEC strains in produce have eae, and most belonged to recognized pathogenic serotypes so are of definite health risks. Several eae-negative strains belonged to serotypes O113:H21 and O91:H21 that historically have caused severe illness and may also be of concern. Most of the other STEC strains in produce, however, are only partially serotyped or are unremarkable serotypes carrying putative virulence factors, whose role in pathogenesis is uncertain, thus making it difficult to assess the health risks of these STEC strains.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.