[Determining the biological activity of levorin by the international standard of candicidin]. / Opredelenie biologicheskoi aktivnosti levorina po mezhdunarod- nomu standartu kanditsidina.

Levorin and candicidin represent close mixtures of heptaenic components. Their physicochemical and biological properties were also close. The antibiotics showed similar diffusive properties in their assay by the agar diffusion method. This made it possible to determine activity of the Soviet levorin standard by the International candicidin standard. For defining the levorin unit in the international units of candicidin, a scaling ratio of 9 was proposed.

[Antibiotic sensitivity of an Escherichia coli strain used for preparing colibacterin]. / Chuvstvitel'nost' k antibiotikam shtamma kishechnoi palochki, ispol'zuemogo dlia prigotovleniia kolibakterina.

Sensitivity of a E. coli strain and commercial colibacterins prepared with its use to 18 antibiotics was tested. The MIC was determined by the method of serial dilutions. It was shown that the strain and colibacterins were sensitive to 9 antibiotics and resistant to the others.

[Nutrient medium for determining the biological activity of heliomycin]. / Pitatel'naia sreda dlia opredeleniia biologicheskoi aktivnosti geliomitsina.

It was shown that a nutrient medium containing only salt components except agar-agar could be used for assay of the biological activity of heliomycin. The optimal results were observed on the medium containing ammonium chloride, urea, disubstituted sodium phosphate, glucose and agar-agar. The medium provided satisfactory growth of Bac. subtilis ATCC 6633 as the test culture and formation of clear inhibition growth zones of the sufficient size. The medium is standard and its use allows obtaining reproducible results in assay of the heliomycin biological activity.

[Basic principles of developing national standards for antibiotics]. / Osnovnye printsipy razrabotki natsional'nykh standartov antibiotikov.

The main principles in preparation of national standards of the antibiotics manufacture in the USSR are compared with those of the World Health Organization. The characteristics of preparing standards of mono- and multicomponent antibiotics, as well as the requirements for optimal packing of the standards are presented.

[Antibiotic sensitivity of bifidobacteria and lactobacteria used in the preparation of bifidobacterin and lactobacterin]. / Chuvstvitel'nost' k antibiotikam bifidobakterii i laktobakterii, ispol'zuemykh dlia prigotovleniia bifidum- i laktobakterina.

Sensitivity of industrial strains and market preparations, such as bifidumbacterin and lactobacterin was studied with respect to 19 antibiotics. The MIC was determined with the method of serial dilutions. It was shown that bifidumbacteria and lactobacteria were either highly sensitive or markedly resistant to the antibiotics.

[Determination of the biological activity of antibiotics by using dry nutrient media]. / Opredelenie biologicheskoi aktivnosti antibiotikov pri ispol'zovanii sukhikh pitatel'nykh sred.

The possibility of using available dry nutrient media Nos. 5 to 12 in assays of antibiotic biological activity with the agar diffusions method was studied with respect to benzylpenicillin, gramicidin S, kanamycin sulfate, kanamycin B, oleandomycin, novobiocin, tetracycline and erythromycin. The dry media were used instead of the respective media prepared with meat hydrolyzate. Optimal conditions of the assays on such media were determined.

[Experience with the international standardization of the biological activity of the 3d Standard for streptomycin]. / Opyt mezhdunarodnoi standartizatsii biologicheskoi aktivnosti tret'ego standarta streptomitsina.

The activity of the third International Standard of streptomycin was determined to be equal to 755 IU/mg with the use of accurately weighed amounts of streptomycin and 78037 IU with the use of streptomycin ampoules. The Standardization Center of the WHO decided to use the whole content of the ampoule of the Third International Standard of streptomycin, the activity of which is determined to be equal to 78500 IU per an ampoule.

[Determination of the biological activity of aminoglycoside antibiotics on a dry nutrient medium of Soviet manufacture]. / Opredelenie biologicheskoi aktivnosti antibiotikov-aminoglikozidov na sukhoi pitatel'noi srede otechestvennogo proizvodstva.

Possible use of the dry nutrient medium manufactured in the USSR for the assay of aminoglycoside antibiotic activity with the agar diffusion method was studied. The optimal conditions for the antibiotic activity assay on this medium were developed. The dry nutrient medium may be used for the activity assay of the aminoglycoside antibiotics, i. e. streptomycin sulfate, dihydrostreptomycin sulfate, neomycin sulfate, monomycin and gentamicin sulfate.