Estrogen increases menopausal host susceptibility to experimental ascending urinary tract infection

The protective effect of estrogen replacement on ascending urinary-tract infection ( UTI) is controversial. We designed a study using an experimental model of UTI in which surgically menopausal mice were supplemented with estrogen and the susceptibility to UTI was evaluated after experimental Escherichia coli infection. The mean rate of E. coli infection in the group not treated with estrogen was 2 x 10(4) cfu/g of renal tissue, compared with 9 x 10(8) cfu/g (P < .001)) in the estrogen-treated group. Surprisingly, despite the hypothesis that estrogen would protect mice from infection, estrogen treatment significantly increased the susceptibility of the mice to ascending UTI.