Influence of oestrogen on experimental pyelonephritis caused by Escherichia coli

Strains of Escherichia coli isolated from patients with suspected pyelonephritis had a strong predilection for growth in kidney tissue. Viable bacterial counts in experimentally infected mice showed that after 96 hours approximately 98% of the total-body count was found in the kidney. Strains of E. coli isolated from cases of gastroenteritis in man and animals had little or no tendency to grow in the kidney. Treatment of male and female mice with oestrogen significantly enhanced the growth of "pyelonephritic" strains in the kidney, but had no effect of any kind on the growth of "gastroenteritis" strains. These preliminary results suggest that oestrogen may predispose to the development of kidney infection in the female and that there is an important link with the virulence of the E. coli concerned. Only those strains that have a natural predilection for growth in the kidney are likely to be influenced by oestrogen.