A Gram-positive diphtheroid isolated from spontaneous cases of cystitis and pyelonephritis of cows on five farms has been studied. All the strains obtained were of the same general morphology. They possess similar cultural characteristics and to a great degree similar agglutination affinities. The organism is not pathogenic for the ordinary laboratory animals. It produces no toxin. Cows injected intravenously with broth cultures failed to develop the disease. On the other hand, small quantities of cultures introduced into the bladder by way of the urethra gave rise to a typical persistent cystitis.
There is evidence for a transmission of the disease by contact infection, as when the same individual curries both normal and infected cows.