Study the presence of genetic determinants of pks pathogenicity island containing clb (colibactin) genes in bacteria of the E. coli M-17 production strain by using PCR.E. coli M-17 cultures isolated from biopreparations bificol (Microgen) and colibacterin (Biomed) and control strain obtained from Tarasevich State Institute on Standardization and Control (Moscow) were studied. Detection of genetic markers of colibacterin was performed by using multiplex PCR with 4 pairs of primers amplifying the main clb genes: clbB, clbN, clbA and clbQ, generating 575, 711, 981 and 820 bp amplicons, respectively.In genome of all the studied E. coli M-17 strains clbB, clbN, clbA and clbQ genes associated with the formation of genotoxic colibacterin were detected.Genome of E. coli M-17 bacteria used for production of probiotic preparations colibacterin and bificol contains genetic determinants ofgenotoxin that require further studies in terms of evidence of harmlessness of production bacteria.