Suckling mouse model of urinary tract infections caused by Escherichia coli.

The role in the vesico-renal pathogenicity of Escherichia coli of mannose resistant fimbriae provisionally designated "119" has been studied in a suckling mouse model. Two to 3 days old mice were infected by route of the urinary bladder and the occurrence and character of the developing infection were investigated. (i) The fimbriated strain caused infection and inflammation of the bladder in almost 100%. In about 60% of the cases it lasted till the end of observations, the 35-37th day following inoculation. The washed, vortexed urinary bladder taken up in 5ml of saline contained a high number (10(6)-10(9)/ml) of bacteria, the urine was often cloudy, containing numerous leucocytes and epithelial cells packed with bacteria. The kidneys were soon involved and by the 23th ad 37th day gross changes were seen in about 25%. In 10%, a classical contracted kidney developed. (ii) The nonfimbriated derivate also caused acute or chronic urinary tract infection, but with a lower frequency and the number of bacteria was also lower by 3-4 log 10 exponents. The model seems to be promising for the study of bacterial infections of the urinary tract and perhaps also for elucidation of its immunological and therapeutic aspects.