Phage Typing of Cholera Vibrio Strains of Serogroup O1, Isolated in the Territory of the Russian Federation in 2024

Currently, cholera remains a relevant infectious disease that requires special vigilance from healthcare professionals and sanitary-epidemiological services. In this regard, the ability to track the likely spread of strains when imported, identify the link between epidemic outbreaks or isolated cases of the disease, and assess the origin of the isolated strains is of particular interest. Phage typing is one of the tools for solving such problems. The aim was to conduct phage typing of strains of cholera vibrios of serogroup O1 received by the Reference Center for Cholera Monitoring in 2024. Materials and methods . The work used 300 non-toxigenic strains of Vibrio cholerae O1 El Tor, isolated from environmental objects in various regions of the Russian Federation during monitoring studies for cholera in 2024. Sensitivity to diagnostic bacteriophages classical, El Tor, typing and experimental phage cocktails was determined. Results and discussion . The studies have shown that 100 % of the strains were resistant to the classic diagnostic cholera bacteriophage, while 17 % were sensitive to the El Tor phage. The use of typing cholera bacteriophages made it possible to determine the phage types of 11 cultures (in Rostov-on-Don – the eleventh one, in Elista, Republic of Kalmykia – the fourth and first ones, in the Donetsk People’s Republic – the twelfth, in the Kherson Region – the seventeenth), which amounted to 5.6 % of the total. At the same time, phage types were identified that had not previously been encountered in the territories of these entities of the Russian Federation, which indicates the imported nature of the isolated strains. 42 cultures were sensitive to the components of the experimental phage cocktails K1 and K2 (K1 – 8 %, K2 – 6 % of all strains). The results of the conducted studies indicate an increase in the phage resistance of the isolated strains of cholera vibrios and the relevance of a regular search for new bacteriophages with an assessment of the possibility of their use as components of diagnostic and prophylactic drugs.