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P2-130 Utility of the FDA-ECID Microarray for Comprehensive Molecular Serotyping of Escherichia coli

Tuesday, July 11, 2017
Exhibit Hall (Tampa Convention Center)
Kyson Chou , U.S. Food and Drug Administration , Irvine , CA
Isha Patel , U.S. Food and Drug Administration , Laurel , MD
Jayanthi Gangiredla , U.S. Food and Drug Administration , Laurel , MD
Nelly Tran , U.S. Food and Drug Administration , Irvine , CA
Donna Williams-Hill , U.S. Food and Drug Administration , Irvine , CA
Richelle Richter , U.S. Food and Drug Administration , Irvine , CA
Peter Feng , U.S. Food and Drug Administration , College Park , MD
Keith Lampel , U.S. Food and Drug Administration , Laurel , MD
Christopher Elkins , U.S. Food and Drug Administration , Laurel , MD
Introduction: With expanding serogroups of Shiga toxin-producing Escherichia coli (STEC), including novel hybrid pathotypes, increasingly causing foodborne illness, serotyping E. coli has become important. Escherichia coli is serologically complex. Over half of the E. coli isolated from foods are untypeable or only yield partial serotypes. A means to quickly determine the serotype of STEC would be useful in surveillance programs to reduce the distribution and consumption of contaminated foods. Serotype data is also critical in epidemiology and outbreak investigations, where it can expedite product recall and minimize outbreak impact.

Purpose: Following the guidelines of the FDA Method Validation Subcommittee, the current study aimed to validate the FDA-ECID microarray, as a rapid means for robust genetic serotyping of E. coli isolates.

Methods: Genomic DNA from a panel of reference E. coli strains were assayed in triplicate on the FDA-ECID microarray. Each strain was analyzed to determine both the O and H determinants, as well as the STEC virulence genes that may be indicative of potential for severe health risks. The array typing results were compared with the known profiles of the corresponding strains.

Results: A hierarchical cluster dendrogram, based on differences in probeset intensities, suggested only 91.8% reproducibility amongst the replicates. To ensure accurate identification of isolates analyzed, modified standard operating procedure for analysis and quality control were developed and implemented. Analysis using quality controlled results showed that for all 85 isolates analyzed, replicates of each isolate clustered together in the dendrogram and had the same serotype that matched the known profiles of the corresponding strains; thus, demonstrating the reliability and validity of the FDA-ECID microarray for genetic serotyping.

Significance: Validation of the FDA-ECID microarray provides another efficient and effective tool for the Agency to use in identifying E. coli and facilitating health risk assessments of pathogenic E. coli in foods.

Back to: Poster Session 2 – Food Chemical Hazards and Food Allergens, Food Toxicology, Meat, Poultry and Eggs, Epidemiology, Retail and Food Service Safety, Communication Outreach and Education, Molecular Analytics, Genomics and Microbiome, Laboratory and Detection Methods, and Dairy
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