[Properties of strains of the causative agent of plague resistant to the diagnostic phage L-413 "c"].

The data obtained in the comparative study of the lytic activity of two plague diagnostic phages, Pokrovskaya's phage and phage l-413 "c", with respect to 655 Y. pestis strains are presented. The study revealed the advantage of Pokrovskaya's phage which lyzed all the strains under test over phage l-413 "c", found to be inactive with respect to 27 Y. pestis strains. The properties of the strains resistant to phage l-413 "c" were typical for the causative agent of plague in the corresponding natural foci.