Combined pre-immunization and granulocyte transfusion therapy for treatment of pseudomonas septicemia in neutropenic dogs.

An experimental model was designed to evaluate a combined protocol of active immunization and granulocyte transfusions for treatment of Pseudomonas aeruginosa sepsis in the neutropenic host. One member of a pair of dogs was immunized with P. aeruginosa vaccine. Both dogs were then rendered transiently neutropenic with a single intravenous dose of cyclophosphamide (40 mg. per kilogram) and challenged with an intravenous inoculum of P. aeruginosa. Twenty-four and 48 hours after pseudomonas challenge each animal received granulocyte transfusions. Effectiveness of therapy was evaluated by observation of survival time, febrile response, and quantitative blood cultures. Results showed a significant increase in the survival period (P is less than 0.05), a lower febrile response (P is less than 0.025), negative blood cultures, and a greater recovery rate in the immune group. Immune dogs that died had negative blood cultures or less than or equal to 10 pseudomonas per milliliter of blood despite the presence of P. aeruginosa in tissues. In contrast, control dogs had septic deaths within 67 hours of pseudomonas challenge, marked febrile responses with 24 hours of infection, and positive blood cultures with 4,000 to 25,800 pseudomonas per milliliter of blood. These data show that combined therapy with immunization and granulocyte transfusions is effective in reducing the severity of P. aeruginosa infection and in preventing bacteremia during periods of leukopenia.