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Activity of levofloxacin, lomefloxacin and moxifloxacin against 20 FI+ and 20 FI- strains of Yersinia pestis was studied. It was shown that the strains were highly susceptible to the fluoroquinolones. In the experiments on mice subcutaneously infected with suspension of strains 231 FI+ and 231 FI- of Y.pestis in a dose of about 1000 LD50 (104 microbial cells) the ED50 of levofloxacin and moxifloxacin was 5.5-14.0 mg/kg independent of the infective culture phenotype and that of lomefloxacin was 18.5 mg/kg. Estimation of the impact of the pathogen infective dose value on the results of the experimental plague treatment with the therapeutic dose equivalent to the human one showed high efficacy of the fluoroquinolones (efficacy index of 104). The treatment for 7 days provided 90-100-percent survival of the animals. The prophylactive use of lomefloxacin (in 5 hours - 5 days) was less efficient (70-80% of the survivals) in the animals infected with the antigen-changed (FI-) variant of the pathogen. Levofloxacin and moxifloxacin provided 90-100-percent survival of the animals treated for a course of 5 days independent of the pathogen phenotype. The study demonstrated that the use of levofloxacin, lomefloxacin and moxifloxacin was prospective for the prophylaxis and therapy of experimental plague.

Despite obvious success in the vaccine development and chemotherapy of influenza, it remains a poorly controlled infection leading to emergence of new pandemic variants of the virus with high morbidity and mortality. We investigated the protective activity of Ingavirin® against the lethal influenza A(H1N1)2009 virus infection on albine mice. Oral use of Ingavirin® resulted in sharp decreasing of the mortality (index of protection up to 57%), slight decreasing of the infectious titer of the virus in the lungs (up to 40-fold), normalizing of the body weight dynamics and the lung tissue structure vs. the placebo-treated control. The degree of the bronchial epithelium damage was also strongly decreased. The results allow to consider Ingavirin® as an effective antiviral against the current pandemic influenza virus.

The efficacy of levofloxacin and moxyfloxacin vs. the previously tested fluoroquinolones was studied on albino mice with experimental plague due to the Nalr mutants of Yersinia pestis 231 and 231 FI-. The plague microbe mutants resistant to nalidixic acid (Nalr) generated at a frequency of 10'10-10'9. The resistance to nalidixic acid was not accompanied by the strains loss of the virulence. The Nalr mutants were cross resistant to fluoroquinolones (ciprofloxacin, moxyfloxacin). The LD50 for the nontreated animals did not differ from that for the mice treated with nalidixic acid and the fluoroquinolones (when the animals were infected with Nalr mutants). The results showed that the criteria of the plague microbe susceptibility/resistance to fluoroquinolones should be revised.