COMPARISON OF ESCHERICHIA-COLI STRAINS RECOVERED FROM HUMAN CYSTITIS AND PYELONEPHRITIS INFECTIONS IN TRANSURETHRALLY CHALLENGED MICE

Urinary tract infection, most frequently caused by Escherichia coli, i s one of the most common bacterial infections in humans. A vast amount of literature regarding the mechanisms through which E, coli induces pyelonephritis has accumulated, Although cystitis accounts for 95% of visits to physicians for symptoms of urinary tract infections, few in vivo studies have investigated possible differences between E. coli re covered from patients with clinical symptoms of cystitis and that from patients with symptoms of pyelonephritis, Epidemiological studies ind icate that cystitis-associated strains appear to differ from pyeloneph ritis-associated strains in elaboration of some putative virulence fac tors.With transurethrally challenged mice we studied possible differen ces using three each of the most virulent pyelonephritis and cystitis E. coli strains in our collection. The results indicate that cystitis strains colonize the bladder more rapidly than do pyelonephritis strai ns, while the rates of kidney colonization are similar. Cystitis strai ns colonize the bladder in higher numbers, induce more pronounced hist ologic changes in the bladder, and are more rapidly eliminated from th e mouse urinary tract than pyelonephritis strains, These results provi de evidence that cystitis strains differ from pyelonephritis strains i n this model, that this model is useful for the study of the uropathog enicity of cystitis strains, and that it would be unwise to use pyelon ephritis strains to study putative virulence factors important in the development of cystitis.