Reduced resistance to Pseudomonas septicaemia in diabetic mice.

Antibacterial resistance in a diabetic state was studied using experimental Pseudomonas infection in streptozotocin (SZ) induced diabetic mice. The results obtained were as follows: (1) there was no difference in acute death rate between normal and diabetic mice when infected with Pseudomonas aeruginosa. However, a significant increase in the number of bacteria in the kidney and liver occurred at a later stage of infection in diabetic mice. (2) Active immunization with a phenolized vaccine resulted in 100% survival in either normal or diabetic mice; otherwise challenge was lethal. However, the organs examined in diabetic vaccinated mice contained distinctly increased numbers of bacteria as compared with normal vaccinated mice 7 days after infection. (3) There were no significant differences in antibody titre between normal and diabetic ice after infection, but passive protection with immune serum from diabetic vaccinated mice was less effective than that from vaccinated mice. Furthermore, immune serum from normal vaccinated mice exerted protective action less efficiently in diabetic recipients than in normal recipients. (4) The bactericidal effect of peripheral whole blood was apparently lower in diabetic mice than in normal mice. (5) Treatment with insulin restored such reduced resistance to Pseudomonas infection in diabetic mice. These findings suggest that the decreased resistance to Pseudomonas infection in diabetic mice should be ascribed to impaired function of antibody, abnormalities in phagocytic cells and disturbed microcirculation caused by the insulin-deficient state.