Uropathogenic Escherichia coli are more likely than commensal E-coli to be shared between heterosexual sex partners

Because uropathogenic Escherichia coli are better adapted than other E coli to the urethra, periurethra, and vagina, the authors reasoned that uropathogenic E coli would be more likely than commensal E coli to be shared between sex partners. In this 1996-1999 Michigan study, the genetic identity of E coli isolated from 166 women with E coli urinary tract infection (UTI) and 94 women without UTI and their sex partners was determined by pulsed-field gel electrophoresis. Rectal isolates were considered uropathogenic E coli if genetically identical to the urinary isolate causing UTI. All eight urinary isolates from men with UTI partners were identical to the E coli found in the urine or vagina of their sex partner. When the 550 unique rectal E coli isolates from couples were considered the unit of analysis, E coli that caused UTI were nine times (odds ratio (OR) = 8.87, 95% confidence interval (Cl): 5.41, 14.54) more likely than other E coli to be shared between sex partners. Sharing occurred twice as frequently (OR = 1.87, 95% Cl: 1.13, 3.08) if the E coli had P pili or if the couples engaged in oral sex (OR = 2.09, 95% Cl: 1.09, 4.00). Uropathogenic E coli are more likely than commensal E coli to be shared with a current heterosexual sex partner. Both sexual behaviors and a bacterial virulence factor, P pili, modified sharing.