Application of a New Nutrient Medium Substrate – Peptone Made from Fibrin – in the Production of Preparations for the Phage Diagnostics of Plague and Cholera

The Russian Research Anti-Plague Institute “Microbe” of the Rospotrebnadzor is the only manufacturer of medical products for phage diagnostics of plague and cholera registered in the Russian Federation. The main stage of diagnostic bacteriophage production is their accumulation in the producer strain culture, which involves the use of nutrient media (NM) with various protein bases. Researchers have noted an increasing number of cases of non-standardization of the latter, which often leads to deterioration in the qualitative and quantitative parameters of phage lysates. The aim of the work was to investigate the possibility of using fibrin peptone as an alternative basis for nutrient media at the stage of bacteriophage accumulation in the production of preparations for phage diagnostics of plague and cholera. Materials and methods. Yersinia pestis EV NIIEG was used as producer strain together with specific bacteriophages such as diagnostic Pokrovskaya and L-413C ones; Vibrio cholerae cholerae O1 145 and V. cholerae El Tor O1 75M and their specific bacteriophages – classical (C) and El Tor (XII and XV), were also used, respectively. The activity and specificity of plague bacteriophages accumulated on experimental nutrient media were tested using Y. pestis and Y. pseudotuberculosis strains, serotypes I–VI. The activity and specificity of cholera bacteriophages accumulated on experimental nutrient media were monitored using the corresponding strains of V. cholerae cholerae and V. cholerae El Tor O1. The composition of liquid nutrient media based on fibrin peptone varied depending on the needs of the cultured microorganisms in terms of the following parameters: amine nitrogen, inorganic and organic cofactor content, and hydrogen index. Results and discussion. The use of fibrin peptone as a nutrient medium base for the accumulation of plague (Pokrovskaya and L-413S) and cholera (C, XII, and XV) bacteriophages has demonstrated the results equal to or superior to those of control nutrient media specified by production regulations. Experimental bacteriophage series, compared with commercial preparations, showed compliance with regulatory requirements.