Descriptive study in which 24 urine samples from older adults with urinary tract infection (UTI), from nursing homes, were evaluated; in order to identify differences in the immune and biochemical response from older adults with UTI by Escherichia coli (E. coli) to major virulence factors in the pathogenesis of UTI. Iron concentration, TNF-α, IL-1β and antioxidant capacity in urine were determined. A relation was found between, an increase in iron and red blood cell concentration in urine, and the presence of the pap GII gene found in E. coli. It is concluded that older adults, with UTIs by E. coli with the gene pap GII, have increased tissue damage.