Effect of vincristine sulfate on Pseudomonas infections in monkeys.

In rhesus monkeys, intravenous challenge with 0.6 x 10(10) to 2.2 x 10(10)Pseudomonas aeruginosa organisms caused acute illness of 4 to 5 days' duration with spontaneous recovery in 13 of 15 monkeys; blood cultures became negative 3 to 17 days after challenge. Leukocytosis was observed in all monkeys. Intravenous or intratracheal inoculation of 2.0 to 2.5 mg of vincristine sulfate was followed by leukopenia in 4 to 5 days. Intravenous inoculation of 4.2 x 10(10) to 7.8 x 10(10) pyocin type 6 Pseudomonas organisms in monkeys given vincristine sulfate 4 days previously resulted in fatal infection in 11 of 14 monkeys, whereas none of four receiving Pseudomonas alone died. These studies suggest that an antimetabolite-induced leukopenia predisposes to severe Pseudomonas sepsis and that such monkeys may serve as a biological model for study of comparative efficacy of antimicrobial agents.