[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 = 0.01). Vaccine strain EV used by conventional way of inoculation (suspension in isotonic solution of NaCl) induced strong antibacterial immunity (index of immunity--10(5)), whereas activated (in lysate of erythrocytes) cells of Y. pestis 231 strain overcame it (index of immunity--10(2)). LD50 value of Y. pestis 231 FI- for immune and nanve animals was 3 m.c. (1 CFU), which demonstrates the absence of ability of EV strain to induce antitoxic immunity in the macroorganism. CONCLUSION: Use of two models of infection allows to make more adequate prognosis of efficacy for relevant vaccine preparations.

[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. pestis in a dose of about 1000 LD50 (10(4) 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 10(4)). 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 oflevofloxacin, lomefloxacin and moxifloxacin was prospective for the prophylaxis and therapy of experimental plague.

[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 0.02-0.08 mg/l, that corresponded to the MICs of ceftriaxone, cefotaxime and ceftazidime. The MICs of cefoperazone were somewhat higher (0.1-0.2 mg/l). The ED50 values of cefixime and cefepime for prevention and treatment of experimental plague in mice statistically did not significantly differ from the ED50 values of ceftriaxone, cefotaxime, ceftazidime and cefoperazone. The efficacy indices (EIs) of cefixime and cefepime were > 10(4) independent of the infective strain phenotype (FI+ or FI-) and did not differ from those of ceftriaxone and ceftazidime. The efficacy of cefotaxime and cefoperazone was somewhat lower (EIs 1.7 x 10(3)-8.9 x 10(3)). Both the antibacterials were shown to provide high protective and therapeutic efficacy (80-100% of the survivors) independent of the phenotype (FI+ or FI-) of the pathogen infective strain. The results allowed to consider the antibiotics prospective in prevention and treatment of plague.

[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. pestis 231 (approximately 1000 LD50) in the dose equivalent to the daily dose for humans. However, no antiplague immunity developed in the survivors: the immunity index (II) of 1.5x10. The use of ceftriaxone according to the same scheme simultaneously with single immunization by F I antigen in a dose of 100 mcg/mouse resulted not only in 100-percent survival of the animals but also in development of expressing antiplague immunity (II 2.2x10(5)). The protection level corresponded to the control with the same live-stock of the animals after a single immunization in the analogous dose of F I antigen (II 3.2x10(4)) and the ceftriaxone use (II 1.0x10(5)), as well as after immunization of the mice by 10(6) microbial cells of Y. pestis EV NIIEG (II 1.2x10(5)). The results of the study are indicative of the prospective use of subsingle vaccines of the new generation based on F I antigen for combined specific and urgent prophylaxis.

[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. cholerae isolated in 1993 and 1994 possessed 3 resistance markers. Studies on albino mice with generalized experimental cholera due to the V. cholerae eltor 1 strain (P-18826, 2005) isolated from a cholera patient, which was highly resistant to nalidixic acid, streptomycin, ampicillin and trimethoprim/sulfamethoxazole and showed cross resistance to fluoroquinolones (ciprofloxacin, ofloxacin, pefloxacin and norfloxacin) and moderate resistance to ceftriaxone and cefotaxime, revealed that the only efficient antibiotics were tetracyclines and aminoglycosides (except streptomycin). The investigation demonstrated an extension of the antibiotic resistance spectra of the epidemically significant strains of the cholera pathogen and the necessity of using antibacterial drugs in strict accordance with the antibioticograms in emergent prophylaxis and therapy of cholera and immediate replacement of the drug by a more active one.

[Efficacy of plague prophylaxis with streptomycin, tetracycline, and rifampicin in simultaneous immunization of white mice by resistant EV NRIEG strain]. / Effektivnost' profilaktiki chumnoi infektsii streptomitsinom, tetratsiklinami i rifampitsinom pri odnovremennoi immunizatsii ustoichivym k nim variantom shtamma EV NIIEG v éksperimentakh na belykh myshakh.

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. The PI for the tetracyclines lowered by 2 orders. Simultaneous prophylaxis with the tetracyclines and immunization by Y. pestis EV Rifr R(SmTc) (10(6) microbial cells) provided not only higher percentage of the animal survival (80-90%) but also development of sufficient plague immunity: PI of 1.0 x 10(5)--5.0 x 10(5). When the animals were infected with Y. pestis 231 R(SmTc) the use of the tetracyclines failed, whereas the use of doxycycline and simultaneous vaccination by EV Rifr R(SmTc) provided survival of 70-85% of the animals. Successive use of inefficient streptomycin (for 2 days) and efficient rifampicin (for 3 days) provided survival only of 30% of the mice. A similar regimen of the successive use of the inefficient and efficient antibiotics (the total term of 5 days) started simultaneously with immunization by EV Rifr R(SmTc) provided survival of 80% of the animals. The use of combined specific and urgent prophylaxis of plague infection due not only to antibiotic susceptible but also to antibiotic resistant strains of the plague pathogen was shown promising.

[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]. / Sravnitel'naia otsenka aktivnosti antibakterial'nykh preparatov in vitro i éffektivnosti pri éksperimental'noi kholere u belykh myshei, vyzvannoi shtammami kholernogo vibriona O1 i O139 serogrupp.

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. The strains of Vibrio cholerae O1 and O139 serogroups isolated within the recent years had transmissive markers of resistance to streptomycin, trimethoprime/sulfamethoxazole, tetracycline, chloramphenicol and not transmitted by conjugation markers of resistance to rifampicin, furazolidone, nalidixic acid. The specific feature of the experimental infection due to such strains was the failure not only of the antibacterials of the resistance spectrum of the pathogen but also of the antibiotics showing in vitro susceptibility (betalactams, fluoroquinolones) that required additional bacteriological control on the 2nd or 3rd day of the etiotropic therapy for early replacement of the antibacterial agent.

[Formation of virulent antigen-modified mutants (Fra-, Fra-Tox-) of plague bacteria resistant to rifampicin and quinolones]. / Izuchenie vozmozhnosti vozniknoveniia virulentnykh antigenizmenennykh (Fra-, Fra-Tox-) mutantov chumnogo mikroba, ustoichivykh k rifampitsinu i khinolonam.

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.10(-9), subsequently. Rifr mutation influenced on virulence manifestation at albino mice and antigendeficient variants with Fra- and Fra-Tox- phenotype. In every group of strains highly virulent subcultures were registered. Resistance to nalidixic acid mainly was not associated with virulence loss. Nalr mutants of parent and antigenmodified mutants were cross resistant to fluoroqinolones (ciprofloxacin, ofloxacin, pefloxacin, lomefloxacin). LD50 for untreated albino mice did not differ from LD50, for mice treated with rifampicin (when mice were infected with strain resistant to rifampicin) or with nalidixic acid and fluoroquinolones (when animals were infected with Nalr mutants). Antigenmodified strains of plague bacteria and their Rifr, Nalr mutants were able to overcome specific immune reaction. The drugs should be used in synergic combinations (with aminoglycosides or cephalosporines of III generation) to prevent appearance of virulent strains resistant to rifampicin and fluroquinolones.

[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]. / Otsenka perspektiv sochetannoi spetsificheskoi profilaktiki antibiotikorezistentnym immunogennym shtammom chumnogo mikroba i ékstrennoi profilaktiki aminoglikozidami na modeli éksperimental'noi chumy belykh myshei.

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. ED50 achieved 1.0-1.2 x 10(3) CFU and in control group (without treatment) 9.3 x 10(2) CFU. Gentamicin and amikacin were highly effective for experimental plague prophylaxis (90-100% animal survival), but inhibited development of postinfective immunity. Protective index (PI) value was 1.1 x 10(2). It was demonstrated that combination of specific prophylaxis (Y. pestis 363 Monr) and emergency prophylaxis with aminoglycosides in albino mice infected with approximately 1000 LD50 of virulent strain Y. pestis 358 (5 hours after infection) was highly effective and provided protective effect against subsequent infection with plague pathogen. Value of PI was 1.1 x 10(5) and practically did not differ from PI (1.7 x 10(5)) in control group (intact mice, immunized with strains EV [symbol: see text] 363 Monr).

[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]. / Ispol'zovanie monoklonal'nykh antitel k antigenam chumnogo mikroba na rannei stadii razvitiia chumnoi infektsii u belykh myshei dlia povysheniia éffektivnosti pozdnego primeneniia streptomitsina i doksitsiklina.

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. pestis 231 prevented infection manifestation at 80 per cent of animals, etiotropic therapy started at the same period was ineffective. When white mice were infected with Y. pestis 231 Fra-, with deleted ability to produce capsule antigen (fraction 1) 80% level of efficacy can be provided by subsequent administration of antibodies to fraction 1 combinated with lipopolysacharide, murine toxine and streptomycin. Use of monoclonal antibodies followed by doxycycline was ineffective.

[Ofloxacin efficacy in the prophylaxis and treatment of experimental plague due to antigen complete and defective strains of the pathogen]. / Effektivnost' ofloksatsina pri profilaktike i lechenii ékperimental'noi chumy, obuslovlennoi prirodnymi i anigenizmennymi shtammami vozbuditelia.

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. In the experiments with albino mice (prophylaxis, 5 days) the ofloxacin efficacy was lower when the infection was due to the plague microbe strains deprived of the ability to produce fraction I and mouse toxin, evident from a statistically significant increase of the drug ED50 and a decrease of the animal survival percentage. When used in the doses corresponding to the human average daily doses, ofloxacin provided effective animal protection (80 to 100 per cent survival) after the prophylaxis for 7 days and the treatment of the plague infection irrespective of the strains, complete or antigen changed. However, when the infection is due to the antigen changed strain, ofloxacin should be used in the maximum daily doses at least for 7 days.

[Experimental evaluation of efficacy of Lactobacilli in prophylaxis and treatment of cholera]. / Eksperimental'naia otsenka éffektivnosti laktobatsill dlia profilaktiki i lecheniia kholery.

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. cholerae was registered in 50% of cases. This strain of lactobacilli was found to be suitable for use as the basis component of probiotic, an additional remedy for the prophylaxis and treatment of cholera.

[Experimental resistance of Vibrio cholerae el tor to nalidixic acid and fluoroquinolones]. / Eksperimental'naia ustoichivost' kholernogo vibriona biotipa él'tor knalidiksovoi kislote i ftorkhinonam.

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. But the efficacy of ofloxacin, lomefloxacin, norfloxacin against these mutants in vivo reduced, though it was not changed in vitro. Mutants of V. cholerae eltor P-5879 resistant to fluoroquinolones and selected after culturing in the presence of the drugs had cross resistance to all quinolones studied. Infection caused by Cpfr mutant could not be treated with nalidixic acid and fluoroquinolones, therapeutic efficacy of rifampicin and beta-lactams, also reduced though sensitivity in vitro was not changed. The results of investigation proves the necessity of quinolones use for cholerae treatment as it is recommended for other severe enteric infections.

[The experimental validation of the advantages of combined emergency (fluoroquinolones) and specific (EV Nalr) prevention of plague versus their sequential use]. / Eksperimental'noe obosnovanie preimushchestv kombinirovannoi ékstrennoi (ftorkhinolony) i spetsificheskoi (EV Nalr) profilaktiki chumy pered ikh posledovatel'nym primeneniem.

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. Use of immunogenic strain EV Nafr (resistant to nalidixic acid and fluoroquinolones) provided antiplague immunity formation at the background of fluoroquinolones prophylaxis. Ciprofloxacin, ofloxacin and pefloxacin used for plague prophylaxis at white mice infected with Yersinia pestis (about 1000 LD50) inhibited postinfective immunity development. Nalidixic acid and norfloxacin didn't demonstrate such effect. Urgent (fluoroquinolones) and specific (EV Nalr) combined prophylaxis was evaluated as more effective for a 5-day period and provided the development of antiplague immunity.

[Characteristics of etiotropic therapy of plaque infection induced by atypical strains of F1- phenotype plaque microbe]. / Osobennosti étiotropnoi terapii chumnoi infektsii, vyzvannoi atipichnymi shtammami vozbuditelia s F1- fenotipom.

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. In experimental plague due to F1- phenotype plague microbe the prophylactic effects of cefotaxime, cefoperazone, sulbactam/ampicillin, azthreonam, ciprofloxacin and rifampicin were lower. However, increase of the daily doses of the drugs and prolongation of the treatment course up to 7 days made it possible to increase the protective effects up to 80-100 per cent. Doxycycline and ampicillin were not sufficiently efficient even when used for 10 days in the prophylaxis of plague due to F1- strains.

[Experimental evaluation of prospects for the use of beta-lactams in plague infection caused by pathogens with plasmid resistance to penicillins]. / Eksperimental'naia otsenka perspektiv ispol'zovaniia betalaktamov pri chumnoi infektsii, vyzvannoi vozbuditelem s plazmidnoi ustoichivost'iu k penitsillinam.

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). Cefoperazone was not active in the treatment of experimental plague induced by the strains containing plasmids RP-1 and R57b (beta-lactamases TEM-2 and OXA-3). Ceftriaxone versus the antibiotics tested was considered to be the drug of choice for the etiotropic therapy of plague induced not only by the type strains of the plague microbe but also by its variants with the plasmid pattern resistance to penicillins.

[The possibility of colonizing the intestines of white mice with Lactobacillus acidophilus during bacterial therapy]. / Vozmozhnost' prizhivleniia Lactobacillus acidophilus v kishechnike belykh myshei na fone bakterial'noi terapii.

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. Good prospects for the use of L. acidophilus strain VKM V-2020 D for further studies regarding its use for prophylaxis and therapy were noted.

[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]. / Sravnitel'noe izuchenie ftorkhinolonov i tsefalosporinov III pokoleniia v profilaktike i lechenii éksperimental'noi chumy, obuslovlennoi tipichnym i serologicheski atipichnym po F1 shtammami chumnogo mikroba.

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. For the prevention of the infection such doses should be used for not less than 7 days. By the efficacy ceftriaxon was superior to the other cephalosporins and should be considered as a drug of choice.

[Third generation cephalosporins (cefoperazone, cefotaxime, ceftazidime and ceftriaxone) in the prevention and treatment of experimental plague in albino mice]. / Tsefalosporiny tret'ego pokoleniia (tsefoperazon, tsefotaksim, tseftazidim, tseftriakson) v profilaktike i lechenii éksperimental'noi chumy belykh myshei.

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 0.5 microgram/ml. A comparative study on the efficacy of the 3rd generation cephalosporins in the treatment of experimental plague in albino mice revealed that the use of cefoperazone, cefotaxime, ceftazidime and ceftriaxone in the therapy of etiotropic plague was promising. Ceftriaxone, an antibiotic with prolonged action, which was the most efficient in the experiments on the laboratory animals was shown to be the drug of choice among the 3rd generation cephalosporins.

[Cefoperazone in the prevention and treatment of experimental plague caused by typical and fraction-free pathogen strains in white mice]. / Tsefoperazon v profilaktike i lechenii éksperimental'noi chumy belykh myshei, vyzvannoi tipichnym i besfraktionnymi shtammami vozbuditelia.

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. Cefoperazone, a 3rd generation cephalosporin, was highly active in the treatment of experimental plague caused by the plague microbe strain typical in the antigen composition: the drug daily dose of 250-500 mg/kg provided an 80-100 percent survival of the albino mice. The efficacy of cefoperazone lowered when the infection was caused by the strain defective in the capsule antigen. The use of the antibiotic for more prolonged periods provided better results of the etiotropic therapy.