Navigation

P3-07 Application of an Array for Rapid Molecular Serotyping, Virulence Determination and Health Risk Assessment of Shiga Toxin-producing Escherichia coli Isolated from Foods

Tuesday, July 28, 2015
Hall B (Oregon Convention Center)
Jayanthi Gangiredla , U.S. Food and Drug Administration , Laurel , MD
Isha Patel , U.S. Food and Drug Administration , Laurel , MD
David Lacher , U.S. Food and Drug Administration , Laurel , MD
Mark Mammel , U.S. Food and Drug Administration , Laurel , MD
Keith Lampel , U.S. Food and Drug Administration , Laurel , MD
Christopher Elkins , U.S. Food and Drug Administration , Laurel , MD
Peter Feng , U.S. Food and Drug Administration , College Park , MD
Introduction: Consumption of foods contaminated with Shiga Toxin-producing Escherichia coli (STEC) have caused several outbreaks worldwide in the last few decades. There are several subtypes of Shiga Toxins but not all affect humans.  Also, there are several hundred known STEC serotypes but many have not caused infections.  Therefore, it is crucial to rapidly identify the pathogenic STEC strains that pose health risks.

Purpose: As part of the FDA’s effort to ensure food safety, the FDA-ECID DNA microarray for molecular serotyping and virulence determination of pathogenic E. coli was evaluated for characterization of various STEC strains isolated from raw milk cheeses and fresh produce samples collected in the last half of 2014.

Methods: The FDA-ECID array has been designed as a rapid, affordable and high-throughput tool for molecular characterization of pathogenic E. coli. Molecular serotyping for the O and H antigens are based on the alleles from the fliC, wzx, and wzy genes that are represented on the array. For virulence determination probe sets are designed for the detection of multiple eae, stx1 and stx2 alleles, as well as other virulence factors.

Results: Thirty-two strains isolated from regulatory food samples were identified as STEC by preliminary PCR and microbiological testing.  The array determined the serotype, Shiga Toxin type, and presence/absence of eae alleles of each STEC strain. One strain isolated from cheese was identified as potential pathogen of concern (O111:H8, stx1, eae γ2) and was recommended for recall. The molecular characteristics of the remaining thirty-one strains provided a basis for their regulatory exclusion.

Significance: The FDA-ECID microarray is a rapid and accurate tool for molecular serotyping and virulence assessment of STEC. Compared to conventional serological analysis that may take up to two weeks and often yields partial data, the FDA-ECID microarray accurately provided the results in two days.

Back to: Poster Session 3 – Laboratory and Detection Methods, Sanitation; Antimicrobials; Produce; Epidemiology
<< Previous Abstract | Next Abstract >>