TABLE 1.

Common features of PAI

Presence of virulence genes
Specific presence in pathogens, absence in benign relatives
Large distinct chromosomal regions (10 to 200 kb)
Characteristic base composition different from core genome
Insertion of PAI adjacent to tRNA genes
Frequent association with mobile genetic elements, i.e., presence of:
    DR
    Cryptic or functional integrase or transposase
    IS elements
    Chromosomally integrated conjugative transposons, plasmids, and phages
Genetic instability (if functional mobility elements are present)
Mosaic structures of several acquisitions