[Efficacy of levofloxacin, lomefloxacin and moxifloxacin vs. other fluoroquinolones in experimental plague due to FI+ and FI- strains of Yersinia pestis in Albino mice].

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.

[Infectious-toxic model of plague in mice].

Aim: To develop infectious-toxic model of plague in mice and to assess perspectives of its use for selection of new vaccine preparations.

Materials And Methods: Cells of virulent strains of Yersinia pestis 231 and 231 FI- incubated in lysates of human erythrocytes for their activation as well as suspensions of these strains in isotonic solution of NaCl were used for subcutaneous inoculation of infection-nanve and immune mice.

Results: It was shown that activated cultures were characterized by maximal virulence (LD50 = 1-3 CFU) and caused rapid infection--mean length of survival reduced on 1 - 3 days (P < or = 0.

[Prophylactic use of ceftriaxone in combination with F I antigen immunization in studies on uninbred albino mice infected by Yersinia pestis. Antiplague immunity development].

Administration of highly immunogenic (ED50 12.6 mcg/mouse) F I antigen (100 mcg/mouse) to albino mice 5 hours after their contamination approximately with 1000 LD50 of Yersinia pestis 231 provided 99-percent survival of same animals (17-50%) and 2-5-day prolongation of the life-span, that was indicative of the phenomenon analogous to the survival phenomenon observed in infected animals immunized by immunogenic strains of the plague microbe. The experiment on the mice confirmed high efficacy of ceftriaxone (100-percent survival) when used prophylactically for 5 days 5 hours after the contamination by Y.

[Efficacy of cefixime and cefepime vs. other cephalosporins in experimental plague of albino mice due to variants FI+ and FI- of the plague microbe].

Efficacy of cefixime and cefepime vs. ceftriaxone, cefotaxime, ceftazidime and cefoperazone was studied in vitro and in the treatment of experimental plague of albino mice due to natural, antigen complete strains of the plague microbe and the pathogen variants deprived of the ability to produce the capsule antigen fraction I (FI- phenotype). The MICs of cefixime and cefepime for 20 FI+ and 20 FI- strains of the plague microbe were 0.

[Activity of 22 antibacterials against O1 and O139 serogroup Vibrio cholerae strains isolated from humans within 1927-2005 in various regions of the world].

Analysis of antibioticograms of 390 O1 and O139 serogroup Vibrio cholerae strains isolated from humans within 1927-2005 in various regions of the world showed that the strains of V. cholerae isolated within 1927-1966 were susceptible to 22 antibacterials, the strains isolated within 1938-1993 possessed 1-3 resistance markers and the strains isolated within 1994-2005 had 3-8 resistance markers including resistance to fluoroquinolones. All the strains of O139 serogroup V.

[Ofloxacin efficacy in the prophylaxis and treatment of experimental plague due to antigen complete and defective strains of the pathogen].

Strains of the plague microbe, antigen complete and defective by fraction I and mouse toxin had the same in vitro susceptibility to ofloxacin (MIC 0.08 mg/L). The drug was superior in its activity to pefloxacin and especially nalidixic acid.

[Comparative evaluation of activity of antibacterial agents in vitro and their efficacy in experimental cholera due to strains of Vibrio cholerae O1 and O139 serogroups in albino mice].

Activity of 16 antibacterial agents against human isolates of Vibrio cholerae O1 and O139 serogroups (P-5879, 4990, 143/23, and MO-45, P- 16065 respectively) was studied in vitro. The efficacy of the agents was studied in a model of generalized cholera in albino mice. Susceptibility of Vibrio cholerae P-5879 (used as the control) in the in vitro experiments with respect to the antibacterial agents correlated with their in vivo efficacy.

[Efficacy of plague prophylaxis with streptomycin, tetracycline, and rifampicin in simultaneous immunization of white mice by resistant EV NRIEG strain].

Tetracycline, doxycycline, streptomycin and rifampicin were used for prophylaxis of experimental plague in albino mice (Yersinia pestis 231, approximately 1000 LD50). The antibiotics were administered 5 hours after the infection for 5 days. Tetracycline and doxycycline provided survival of 60 to 75% of the animals, while the respective figure for streptomycin and rifampicin was 100%, but streptomycin and rifampicin inhibited development of plague immunity evident from a lower protection index (PI) by 3-4 orders.

[Formation of virulent antigen-modified mutants (Fra-, Fra-Tox-) of plague bacteria resistant to rifampicin and quinolones].

Experiments were performed with two strains of plague bacteria--231 (isolated from marmot) and 358 (isolated from human) and their isogenic variants with Fra- and Fra-Tox- phenotype. Mutants resistant to rifampicin (Rifr) and nalidixic acid (Nalr) appeared independently of pathogen phenotype and genotype with frequency n.10(-8)-n.

[Evaluation of outcomes of combined specific prophylaxis with the antibiotic resistant immunogenic plague pathogen strain and emergency prophylaxis with aminoglycosides in the experimental plague model in white mice].

It was shown that aminoglycosides (streptomycin, kanamycin, gentamicin, sisomicin, tobramycin, amikacin) prevented manifestation of postvaccine immunity in albino mice immunized by vaccine strain Yersinia pestis EV. Avirulent strain Y. pestis 363 Monr with chromosome resistance to aminoglycosides of the 1st, 2nd and 3rd generations provided manifestation of antiplague immunity when streptomycin, kanamycin, gentamicin and amikacin were administered for prophylaxis.

[Use of monoclonal antibodies to plague microbe antigens at the early stage of infection in white mice for enhancement of the late streptomycin and doxycycline treatment].

It was demonstrated that use for prophylaxy (after 5 h of infection) or for treatment (after 24 h after infection) of the monoclonal antibodies mixture to specific epitops of capsule antigen (fraction 1), lipopolysacharide, murine toxine can prevent development of plague pathogen at 100 of mice infected by approximately 1000 LD50 Yersinia pestis 231. 5-day course of prophylaxy by monoclonal antibodies provided survival of 50 per cent animals. Subsequent use of fraction 1 antigen for 5 days followed by treatment with streptomycin or doxycycline at 6-7-8-9-10 days after infection with Y.

[Experimental evaluation of efficacy of Lactobacilli in prophylaxis and treatment of cholera].

Investigations on experimental models of cholera ("sealed" mice and suckling rabbits) demonstrated that previous daily oral administration of the ferment culture of Lactobacillus acidophilus BKM B-2020[symbol: see text] in a dose of 3.0 x 10(8) microbial cells/ml daily for 5-7 days prevented to the development of Vibrio cholerae infection. The curative effect observed after 3 administrations of lactobacilli within 48 hours after infection with V.

[Experimental resistance of Vibrio cholerae el tor to nalidixic acid and fluoroquinolones].

It was shown that sensitivity of Vibrio cholerae eltor P-5879 to tetracycline, levomycetin, furazolidone, trimethoprim/sulfamethoxazole, aminoglycosides, beta-lactams, rifampicin, quinolones in vitro correlated with drugs efficacy in the treatment of experimental cholera of albino mice. Mutants of V. cholerae eltor P-5879 Nalr resistant to nalidixic acid (MIC 160-200 mg/l) formed with frequency 10(-9)-110(-8) had no cross resistance to fluoroquinolones.

[The experimental validation of the advantages of combined emergency (fluoroquinolones) and specific (EV Nalr) prevention of plague versus their sequential use].

Mice immunization with reference vaccine at the early stage of plague infection provided animals survival and prolonged mean survival period up to 2-5 days. Ciprofloxacin, ofloxacin and pefloxacin prevents development of post vaccine immunity at white mice, immunized by reference vaccine strain EV. Nalidixic acid and norfloxacin effect on post vaccine immunity was lower.

[Experimental evaluation of prospects for the use of beta-lactams in plague infection caused by pathogens with plasmid resistance to penicillins].

High therapeutic efficacies of ceftriaxone, ceftazidime, cefotaxime and azthreonam in the treatment of experimental plague induced by beta-lactamase-producing strains of the plague microbe containing R plasmids RP-1, R57b and R40a were shown to correlate with their in vitro antibacterial activities. The therapeutic efficacy of sulbactam/ampicillin was recorded in the treatment of plague induced by the strain containing R plasmids R57b and R40a (the treatment course of 7 days). However, it was lower when the infection was due to the strain containing plasmid RP-1 (beta-lactamase TEM-2).

[Characteristics of etiotropic therapy of plaque infection induced by atypical strains of F1- phenotype plaque microbe].

The efficacy of various group antibacterial drugs: aminoglycosides, quinolones, 3rd generation cephalosporins, doxycycline, rifampicin, ampicillin and azthreonam was estimated in the treatment of experimental plague of albino mice induced by antigen complete and atypical strains of the F1- phenotype plague microbe. The in vitro experiments showed that all the strains of the plague microbe irrespective of the phenotype (F1+ or F1-) were highly susceptible to the drugs. The animal experiments demonstrated that aminoglycosides (streptomycin, kanamycin, tobramycin, gentamicin and amikacin) and cephalosporins (ceftriaxone and ceftazidim) were highly efficient in the prophylaxis and treatment of plague due to F1+ and F1- strains.

[A comparative study of fluoroquinolones and 3rd-generation cephalosporins in the prevention and treatment of experimental plague caused by Yersinia pestis strains typical and serologically atypical with respect to F1].

Fluoroquinolones (ciprofloxacin and pefloxacin) and 3rd generation cephalosporins (cefoperazone, cefotaxime, ceftazidime and ceftriaxone) were comparatively studied in the prevention and treatment of experimental plague in albino mice caused by F1+ and F1- strains of the plague microbe. Despite the phenotype of the strain which caused the infection, the drugs were highly efficient in the etiotropic therapy. However, in the experimental plague due to F1- strains it was needed to use the maximum mean daily doses of the fluoroquinolones, cefoperazone and cefotaxime.

[The possibility of colonizing the intestines of white mice with Lactobacillus acidophilus during bacterial therapy].

The study revealed the possibility, on principle, for L. acidophilus strain VKM V-2020 D to colonize the intestine of white mice with the preservation of the viability of lactobacilli subjected to the action of antibiotics. The culture of this strain, isolated from the animals, showed the stability of its biological properties: resistance to polymyxin M, kanamycin, cyprofloxacin, nalidixic acid (including acquired resistance to rifampicin), as well as pronounced antagonism with respect to Vibrio cholerae.

[Third generation cephalosporins (cefoperazone, cefotaxime, ceftazidime and ceftriaxone) in the prevention and treatment of experimental plague in albino mice].

Strains of the plague microbe of different origin were found to by highly susceptible to the third generation cephalosporins such as cefoperazone, cefotaxime, ceftazidime and ceftriaxone. The MICs ranged form 0.012 to 0.

[Cefoperazone in the prevention and treatment of experimental plague caused by typical and fraction-free pathogen strains in white mice].

The high susceptibility of the plague microbe to cefoperazone (MIC of 0.1-0.25 microgram/ml) did not depend on the causative agent ability to produce fraction I.

[Beta-lactam antibiotics (ampicillin, cefotaxime) in prevention of experimental plague in albino mice, caused by non-fractioned strains of the pathogen].

The prophylactic action of betalactam antibiotics such as ampicillin and cefotaxime in plague was studied on albino mice infected subcutaneously by Fra+ (Y. pestis 231) and Fra- (Y. pestis 231 Fra-, K-16) variants of the plague microbe.

[Virulence of rifampicin and quinolone resistant mutants of strains of plague microbe with Fra+ and Fra- phenotypes].

Experiments with 15 highly virulent antigenically typical strains (Fra+) and 3 fraction-free strains (Fra-) of the plague microbe were conducted. It was demonstrated that a single exposure of the plague microbe to rifampicin or nalidixic acid (100 micrograms/ml) resulted in the formation of mutants (Rifr or Nalr) resistant to the drugs. The mutation frequency was 10(-10)-10(-8).

[Doxycycline in the prevention of experimental plague induced by plague microbe variants].

A comparative study was performed on the efficacy of doxycycline in experimental plague infection induced in albino mice by strain 231 of the plague microbe and its variant 231 Fra- deprived of the ability to produce the fraction I antigen. It was shown that the LD50 for strain 231 during animal treatment with doxycycline was significantly higher than that for variant 231 Fra-. Prophylaxis of the plague infection caused by the Fra- forms of the plague microbe required significantly higher doses of doxycycline (ED50) than that of the infection caused by the Fra+ forms.