INDUCTION OF URINARY-TRACT INFECTION BY INTRAURETHRAL INOCULATION WITH ESCHERICHIA-COLI REFINING THE MURINE MODEL

Murine models are important for studying the induction and pathophysio logy of ascending urinary tract infections (UTI). However, when vesico ureteral reflux occurs during intravesical inoculation of mice with ba cterial suspensions, it is difficult to distinguish between naturally ascending infections and those resulting from the inoculation procedur e. The current study investigated whether introducing a bacterial susp ension into the urethra rather than into the bladder could minimize or eliminate this complication. There were no differences in the intensi ty or time course of bladder infections induced by intraurethral or in travesical inoculation. In contrast, the prevalence of kidney infectio ns was <7% in mice given 10 mu L of intraurethral inoculations versus nearly 60% in animals inoculated intravesically with 100 mu L. There w ere equivalent numbers of bacteria in the kidneys after inoculation by either route. Thus, intraurethral inoculation of female mice with a s mall volume of bacteria appears to simulate most closely the pathophys iology of ascending UTIs in humans.