[The virulence of Vibrio cholerae isolated under different epidemiological situations]. / O virulentnosti Vibrio cholerae, vydelennykh v razlichnykh épidemiologicheskikh situatsiiakh.

The virulence of V. cholerae isolated on the territory of Russia and other CIS countries from environmental objects and from humans in different epidemic situations during the period of 1987-1991 was studied. The analysis of the data obtained in this study revealed that intensive epidemic complications were linked with the realization of the pathogenic properties of strains, characterized by the presence of the ctx gene and the absence of hemolytic activity. As a rule, in single cases or in isolated group cases of cholera V. cholerae hemolysin-negative strains without the cholera toxin gene were isolated.

[Detoxifying effect of antibiotics and their effectiveness in experimental plague at the stage of explicit intoxication]. / Detoksitsiruiushchee deistvie antibiotikov i ikh éffektivnost' pri éksperimental'noi chume na stadii vyrazhennoi intoksikatsii.

The effect of antibiotics such as amikacin, rifampicin, doxycycline, polymyxin B and cefotaxime on the toxins of the plague microbe (lipopolysaccharide + fraction II according to Beiker) was studied in vitro and in vivo. The study on the antibiotic neutralization of plague toxins revealed that only polymyxin had toxin neutralizing capacity which depended on the dose. Investigation of the polymyxin effect at various stages of plague infection showed that when polymyxin in a dose of 1250 units and a mixture of plague toxins in lethal doses were administered simultaneously to albino mice, the positive effect amounted to 100 per cent. When the antibiotic was administered 30 or 60 minutes later, the antibiotic efficacy proved to be lower by 90 or 76.6 per cent, respectively. The intoxication in later periods (in 90-120 minutes) resulted in a decrease in animal survival up to 40-15 per cent. It was demonstrated on the model of the plague infection in albino mice that the use of amikacin, cefotaxime, rifampicin or doxycycline during polymyxin therapy at the stage of marked generalization of the infection provided a significant increase in the animal survival (60 to 80 per cent) as compared to that after the use of the same drugs alone (0 to 20 per cent).

[Interserovar antitoxic immunity to Vibrio cholerae toxins]. / Mezhserovarnyi antitoksicheskii immunitet k toksinam kholernykh vibrionov.

The immunochemical affinity of V. cholerae enterotoxins, serovars Inaba and Ogawa, has been shown in animal experiments on cross antitoxic immunity in the small intestine, the passive hemagglutination test and the toxin neutralization test. However, antitoxic interaction with both enterotoxins is characteristic only for antibodies to V. cholerae of serovar Inaba, while in animals immune to Ogawa toxin the choleragenic effect of enterotoxins produced by V. cholerae of both serovars in retained. The possible mechanisms of one-sided cross interserovar antitoxic immunity in cholera are discussed.

[Electron microscopic study of the small intestine in experimental cholera]. / Elektronno-mikroskopicheskoe issledovanie tonkogo kishechnika pri éksperimental'noi kholere.

Ultrastructure of the small intestine was studied in nursling rabbits infected with the El Tor 5879 vibrio culture. Cholera vibrio was localized in the intestinal lumen mostly in the crypts area, in some places adhering to the brush edge of enterocytes without penetrating them. Epithelium of the villae remained intact; it however displayed dystrophic changes of microvilli and organoids, cytoplasma vacuolization and increase in lysosome count. The mentioned changes pointed to a marked elevation of functional enterocyte activity in cholera.