Visualization of pathogenicity regions in bacteria.

We show here how pathogenicity islands can be analysed using GenomeAtlases, which is a method for visualising repeats, DNA structural characteristics, and base composition of chromosomes and plasmids. We have applied this method to the E. coli plasmid pO157, and the Y. pestis plasmid pPCP1. In both cases pathogenic genes were shown to differ in A + T content and structural properties. Furthermore, examination of an antibiotic resistance gene cluster from S. typhimurium showed that the same was true for genes encoding antibiotic resistance.