Fig. (6) A. Survival of BALB/c mice challenged with 3 LD₅₀F. tularensis SCHU S4 by nasal instillation followed by treatment with various doses of levofloxacin. The horizontal bar indicates the period of treatment (13 days). Significance from the control was determined by the Fisher Exact Test (p<0.05), and all of the groups of mice except for the 0.1 mg/kg/day dose of levofloxacin were significant. B. Survival of BALB/c mice challenged with F. tularensis SCHU S4 followed by treatment with 40 mg/kg/day starting at various times post challenge. The period of treatment was 13 days. Significance from the control was determined by the Fisher Exact Test (p<0.05) and all of the groups of mice, except for the one to which antibiotic treatment, was administered 120 h postinfection, were significant.