Evolution of pathogenicity islands of Salmonella enterica

Virulence genes located on pathogenicity islands play a crucial role in the pathogenesis of Salmonella enterica infections. Salmonella pathogenicity islands (SPI) contribute to host cell invasion and intracellular pathogenesis. At present, 12 SPI have been described. Although size, structure and function of these SPI, as well as the distribution in Salmonella subspecies and serovars can be markedly different, several common motifs are present among SPI. In this review, the characteristics of SPI are described with focus on the evolution of these genetic elements. (C) 2004 Elsevier GmbH. All rights reserved.