Are the data on STEC prevalence based on PCR positives. Or culture confirmation?
Data on STEC prevalence are based on culture confirmation.
How long does it take to get results for O157? How soon will individuals be able to do their own testing? In other words, are efforts being made to develop simple testing mechanisms for farmers?
Using the methods in this study, isolation and confirmation of E. coli O157 requires a minimum of approximately 3 days. These culture-based methods involve multiple steps and must be conducted by trained personnel in a BSL-2 laboratory due to the pathogen’s risk level. At present, there are no widely adopted simple, on-farm testing methods for O157 that provide reliable results comparable to laboratory-based approaches. While research is ongoing to develop more rapid and field-deployable detection tools, these are not yet standard practice. Importantly, current produce safety regulations do not require growers to test products or the environment for pathogens such as O157. Instead, food safety systems emphasize preventive practices to minimize contamination risks.
Ooh, I want more on the number of colonies influencing culture confirmation!!!!!
These data are currently being analyzed with plans to publish a manuscript in 2026 or 2027. The data will be presented as a poster at the annual meeting of the International Association of Food Protection (IAFP). The abstract will be available then. Moyne, A.L., Durbin, E., Long, S., Leonard, S., Kase, A. J., Guzman, R. J., Jin, Q., Harris, L.J. 2026. Recovery of Shiga toxin-producing Escherichia coli is impacted by environmental matrix. (Abstract PTBD). Monday, July 27, 2026. Annual IAFP meeting 2026, New Orleans, LA, July 26-29.
What methodology is used in the lab for ID? Plating? PCR?
All matrices are processed through enrichment for the detection of STEC (O157 and non-O157) by following the BAM chapter 4A method https://www.fda.gov/food/laboratory-methods-food/bam-chapter-4a-diarrheagenic-escherichia-coli. Enrichments are tested by real-time PCR followed by plating and recovery of STEC isolate. Presumptive STEC colonies are confirmed by real-time PCR and sequenced. Sample is considered positive if one or more STEC-confirmed colony is recovered.
What were your specific objectives/ hypotheses for these studies?
Identifying environmental factors contributing to the introduction, persistence, and movement of foodborne pathogens that could contaminate produce prior to harvest in the California Central Coast.