Distribution of Virulent and Avirulent Subclones of E. coli  O157:H7 in the U.S.

The ability to distinguish between virulent and avirulent sublcones of E. coli O157:H7 was determined by genetic fingerprinting. Methods were developed and refined to improve the analysis of data in this field.

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Objectives

To develop and validate a test that can rapidly discriminate different subpopulations of E. coli O157:H7.

Conclusions

This project used high-density OBGS analysis to identify lineage-specific markers which were then multiplexed into a single rapid PCR assay. The test was validated against a large strain set previously tested by OBGS analysis. The genome coverage phase of the project employed 170 different OBGS primer combinations on the set of 40 representative O157:H7 strains.

Deliverable

The developed assay is being used for two different applications. The first application is examining the distribution of the two lineages in a large number of clinical O157:H7 isolates. A set of >100 strains from the Nebraska State Public Health laboratory is being tested and are in the process of building collections from other public health laboratories. Secondly, the assay is being used to examine distribution of the populations in animal production environments and testing whether certain populations of the organism are more efficient than others at causing “blooms” of infection among cattle.