Pathogenicity Islands of Extraintestinal Escherichia coli

While intestinal Escherichia coli strains can be grouped into at least six different pathotypes, extraintestinal E. coli strains fall into three groups: MENEC (meningitis E. coli) strains, which cause newborn meningitis (NBM), SEPEC (septicemia E. coli) strains, which cause meningitis and septicemia, and UPEC (uropathogenic E. coli) strains, which are by far the most common cause of uncomplicated cases of urinary tract infections (UTIs). This chapter focuses mainly on UPEC because urinary tract infections represent, by number, the most important bacterial infectious disease in highly industralized countries. At least four pathogenicity islands (PAIs) are present in the genome of UPEC 536. Sample sequencing analysis of PAI IJ96, PAI IIJ96, and PAIs I536 to IV536 was performed by investigating overlapping cosmid clones; the results of this analysis are discussed. Integrase genes and other bacteriophage-specific sequences may have played an important role for the evolution of pathogenic bacteria and that their presence on PAIs is one of the main characteristics of PAIs. The newly acquired sequences often form blocks of DNA which may code for virulence but also code for other distinct properties such as secretion, degradation of xenobiotic compounds, metabolic functions, and resistance to antibiotics. PAIs of UPEC strains are excellent examples for the study of the evolution of prokaryotic genomes in pathogenic and nonpathogenic microbes.