The in vitro activities of Moxifloxacin and Amoxicillin are compared by time-kill curve and inhibition of intracellular growth experiments by using a model of bone marrow-derived mouse macrophages infected by L. monocytogenes EGDe. Moxifloxacin acts much more rapidly, beginning to exert its effects in the first 3 h and achieving complete broth sterilization within 24 h of incubation. Moxifloxacin appears to have a protective effect against macrophage lysis, as many cells are still viable after 24 h of incubation.