1. Introduction
Urinary tract infections (UTIs) are the most common type of
nosocomial infection in females and males, and have resulted in
billions of dollars in medical care costs.1,2 The most important cause
of 80e90% of all UTIs is Escherichia coli.3 Nonpathogenic strains of
E. coli are important facultative aerobes in the normal intestinal
flora of human and animals. However, pathogenic strains of these
bacteria are the most common cause of urinary tract infections.4
Uropathogenic E. coli infects the urinary tract by producing special
surface proteins (adhesins), which make them to attach to and
attack the epithelial cells that line the urinary bladder.5 If pathogenic
E. coli is in the bladder (uncomplicated UTI), and is not
eliminated, it may travel up the ureters to the kidneys and cause
complicated UTIs which can be accompanied by renal damage and
renal failure.3,4,6 The development of antibiotic resistance in bacteria
is a growing problem worldwide. A number of E. coli isolates
have been collected from urine specimens of patients with UTI that
are resistant to antimicrobial agents commonly used to treat UTIs