Prevalence and significance of virulence genes in Escherichia coli isolates causing urinary tract infections (uropathogenic E. coli)

Urinary tract infections (UTIs) are among the commonest bacterial infections, responsible for considerable morbidity and mortality. Most studies of UTI pathogenesis have been in women, in whom UTI is commonest. Men and children are also affected but few studies have assessed characteristics of urinary pathogens in these groups. In children, particularly, early detection and treatment is crucial in preventing complications and further studies are needed to enhance our understanding of UTI pathogenesis. Uropathogenic E. coli (UPEC) that cause most UTIs, possess virulence factors (VFs) that help them to colonize, invade and injure the host, including adhesins, toxins, siderophores, surface polysaccharides and proteins. The numbers of genes that can be detected in commonly used PCR methods for VF detection, are limited. We developed a sensitive and specific multiplex PCR-based reverse line blot hybridization assay, which can identify up to 43 targets in each of 43 DNA samples, simultaneously (Paper I), and used it to study 22 VFs in E. coli isolates.A total of 1645 E. coli including urinary isolates from patients with cystitis, pyelonephritis and fecal isolates from healthy controls, were studied, from 327 children (≤ 5 years), 389 men (30-70 years) and 953 women of reproductive-age (15-40 years). All subjects lived in the Central West region of New South Wales, Australia, and isolates were collected during a 2-year period from June 2009-June 2011.