Renal infection in the rat after reflux challenge with Pseudomonas aeruginosa.

A rat-pseudomonad reflux model was employed to examine the effect of the size of inoculum on the emergence of renal infection. Widely varying degrees of renal disease observed in challenged animals indicated that a number of variables influenced the outcome of the host-parasite interaction. In this regard, animals in which there was a reduction of the colony counts below a threshold figure rarely gave evidence of renal infection when examined at autopsy on the eighth day following reflux. These results suggest that a threshold level of bacteriuria may also have to be exceeded if renal infection is to become established in patients with vesico-ureteric reflux.