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P2-73 Shiga Toxin-producing Escherichia coli H Antigen Clustering Evidenced by the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) Array

Tuesday, July 30, 2013
Exhibit Hall (Charlotte Convention Center)
Magaly Toro, University of Maryland-College Park, College Park, MD
Ruth Timme, U.S. Food and Drug Administration, College Park, MD
Wenting Ju, University of Maryland-College Park, College Park, MD
Guojie Cao, University of Maryland-College Park, College Park, MD
Marc Allard, U.S. Food and Drug Administration, College Park, MD
Jianghong Meng, University of Maryland-College Park, College Park, MD
Introduction: Shiga toxin-producing Escherichia coli (STEC) is a leading foodborne pathogen in the U.S., causing serious disease and other health complications. In response, several STEC serogroups are considered adulterants and are banned from meat products. The development of new detection and subtyping approaches for foodborne pathogens depends on the identification of novel molecular markers. A recently discovered genetic element –CRISPR array— is present and variable in Escherichia coli. In this study, we are exploring the utility of CRISPR as genetic marker.

Purpose: To characterize the CRISPR array in Shiga toxin-producing E. coli.

Methods: The CRISPR arrays of 195 E. coli isolates were characterized by PCR amplification and DNA sequencing. The CRISPR elements were extracted using a combination of the “CRISPRFinder” online utility and an Excel macro, and then graphically displayed using the described macro.  Along with the CRISPR data we also screened for select pathogenicity genes –eae, stx1 and stx2, and hlyA.

Results: CRISPR1 and CRISPR2 arrays of 195 strains show minimal variations within a serotype, but more than one type of sequence within a serogroup exist. Interestingly, almost identical arrays are shared by strains from different serogroups; these strains have the same H type (O26:H11, O103:H11 and O111:H11). Serotypes O45:H2 and O103:H2 share similar arrays as well. Finally, CRISPR 3 and CRISPR 4 were detected in only one of the 195 isolates, but a residual CRISPR3-4 array was detected in 10 strains.

Significance: This characterization of CRISPR array in STEC could lead to the development of molecular methodologies for the detection and subtyping of this pathogen.

Back to: Poster Session 2 - Pathogens, Antimicrobials
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