Prediction of pathogenicity islands in enterohemorrhagic Escherichia coli O157:H7 using genomic barcodes.

The genome of lethal animal pathogenic bacterium Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is characterized by the presence of multiple pathogenicity islands (PAIs). Computational methods have been developed to identify PAIs based on the distinguishing G+C levels in some PAI versus non-PAI regions. We observed that PAIs can have a very similar G+C level to that of the host chromosome, which may have led to false negative predictions using these methods. We have applied a novel method of genomic barcodes to identify PAIs. Using this technique, we have successfully identified both known and novel PAIs in the genomes of three strains of EHEC O157:H7.