[A simple biological method for the fast identification of antibiotics].

A method used to determine the quantitative and qualitative determination of antibiotics in blood, injury discharge, in human and animal urine as well as in foodstuffs (meat, milk and products made of them) is described. It is based on using obligate, thermophilic bacteria Bacillus stearothermophilus, strains KK BKM B-213OD and BKM B-718 with an optimum growth at 55-60 degrees C. Meso- and psychrophilic bacteria cannot grow at the above temperature, therefore, the studied non-sterile material does not need any preliminary thermal treatment prior to the indicator-strain, which is highly sensitive to all widely used antibiotics, is sown in the test-culture bacterial lawn.

[The possibility of preserving the causative agent of plague in soil in resting (nonculturable) form].

The parallel study of soil specimens from the burrows of great gerbils, taken in the natural focus of infection at the period between epidemics, by the bacteriological method and with the use of polymerase chain reaction (PCR) demonstrated that, simultaneously with the negative results of inoculations into nutrient media, PCR revealed the presence of Y. pestis in 4 out of 72 soil specimens. The serological study (in the indirect hemagglutination test) revealed the presence of Y.

[The problem of natural foci of plague: the search for ways for its resolution].

The paper deals with one of the most important problems of plague natural foci, namely the places and types of its bacillus persistence outside the parasitic system, as well as in the interepizootic period. It also discusses different hypotheses forwarded on the basis of field observations and experimental findings. In particular, it gives the materials suggesting that the plague bacillus can persist in the low-virulent form under natural conditions, as well as due to its transition to a L-form.

[The protective properties of different Legionella antigens in experimental Legionella infection].

The protective properties of Legionella antigenic preparations were studied on guinea pigs with experimental Legionella infection. Preliminary immunization of guinea pigs with serotypic antigen, cytolysin, as well as live or formalin-treated Legionella cells, did not protect the animals from the subsequent aerogenic infection with 10(5) colony-forming units of virulent L. pneumophila.

[Production of pesticins on synthetic nutrient media].

It was found that 96.2 per cent of the plague microbe cultures studied had a capacity to produce pesticin I on solid and liquid minimum synthetic nutrient media providing growth of the cultures. No pesticin III was detected in the spheroplasts of plague microbes, when they were grown on the synthetic nutrient medium, while on the complete nutrient medium the inhibition zones were observed which was indicative of pesticin III synthesis.

[Effect of formaldehyde and its aminomethylol derivatives on E. coli strains with various defects of the DNA repair systems].

It was shown that aminomethylol compounds formed during reaction of formaldehyde with amino acids and formaldehyde as well exert a pronounced lethal action on E. coli strains with various defects of the DNA repair systems. The correlation between the extent of the DNA depurination caused by in vitro action of diverse aminomethylol derivatives and the inactivation of bacteria by these derivatives is revealed.

[Occurrence of induced vitamin-dependent mutants of Yersinia pestis].

Vitamin-dependent mutants were isolated from Yersinia pestis after the treatment with supermutagens. From 13 mutants obtained 10 appeared to be unstable. The stable vitamin-dependent mutants were revealed with the frequency of 2.