Murine model for therapy of listeriosis in the compromised host. I. Effect of ampicillin.

Therapy of listeriosis with ampicillin was examined in two murine models with compromised defense mechanisms. In mice treated with dextran sulfate paralysing the function of the macrophage system, ampicillin was less able to reduce death rates as well as bacterial counts in the spleens than after infection of normal mice. In nude mice with chronic listeriosis, treatment with ampicillin was started 8 days after infection. The numbers of viable listeria cells decreased under therapy, but a bacteriologic cure was not achieved in a 6-day schedule. Relapse followed cessation of therapy.