Protection against experimental Proteus mirabilis pyelonephritis in rats and significance of immunity.

Intraperitoneal immunization with formalin-killed bacteria as well as previous hematogenous infection with Proteus O3H1 showed a protective effect against hematogenous pyelonephritis in rats when the homologous strain was used. Transfer of hyperimmune antisera protected against hematogenously induced infection. Neither intravesical or intraperitoneal immunization with formalin-killed bacteria nor transfer of urines containing antibodies of the IgG class protected against ascending pyelonephritis when the O3H1 strain was used. Data are presented indicating that a rise of pH might decrease the biological effect of antibodies, suggesting that Proteus urease activity is a virulence factor of importance in this context.