Figure 6.

Antibiotic treatment with ciprofloxacin compared to doxycycline against pulmonary Y. pestis infection, 25 days postinfluenza infection. (A) Experimental scheme for antibiotic treatment: naïve mice were i.n. infected with a lethal dose of 100 LD₅₀ Kim53 or with a similar dose of Kim53 administered 25 dpii. Antibiotic treatment was started 24 h after Y. pestis exposure for 5 consecutive days with Cipro (40 mg/kg q 24 h) or with Doxy (50 mg/kg q 12 h). (B) Kaplan–Maier survival curves of mice i.n. infected with Kim53 (black) or with Kim53 at 25 dpii (blue). Kaplan–Maier survival curves of mice infected i.n. with Kim53 (black) or with Kim53 at 25 dpii (blue) and treated with Cipro (C-I) or Doxy (D-I) n = 8 and n = 12–20 from 2 and 3 independent experiments for Cipro and Doxy, respectively. Bacterial loads in the lungs of infected mice treated with Cipro (C-II) or Doxy (D-II) at the indicated time points after the last antibiotic treatment. Dotted lines denote the detection cutoff of 10 cfu per organ. The inner line indicates the median. Neutrophil percentage in the lungs of infected mice treated with Cipro (C-III) or Doxy (D-III) at the indicated time points after the last antibiotic treatment. n = 7–12 from 2 (for Cipro) or 3 (for Doxy) independent experiments. The data presented as mean ± SEM. **p < 0.01 vs Kim53 + Cipro or Kim53 + Doxy at the same time point.