[Plasmid spectra and phagotypes of Escherichia coli strains isolated from patients with large intestine tumours].

The work deals with connection between plasmid spectra and phagotypes of Escherichia coli strains isolated from patients with tumours in large intestine. It has been established that 70 % of this bacterium isolates from the normal tissue, intestine lumen and tumours are characterized by multiple content of plasmids. Sometimes large endogenic plasmids are accompanied by the closed ring DNA with discrete sizes: 3.2; 3.8 and 4.0 kb. Other extrachromosomal factors have the size of 63-119 kb and are divided into 5 discrete classes. Plasmid DNA which size is 69 and 119 kb occur rarely and are characteristic of only E. coli isolated from the tumour tissue. Cells of three isolates found in the tissues and intestine lumen contain a plasmid complex which consists of three different extrachromosomal DNA of 63, 82 and 102 kb. The complex availability correlates as a rule with multiple strain resistance to ampicillin, canamycin, and tetracycline. Variability of plasmids of clinical E. coli isolates is completed regularly by various phagotypes established by means of virulent bacteriophages T2, T4, T7, FE44, TuIb, Ox2 and MS2. In most cases one could trace interrelation between the plasmid spectrum and phagotype; the same phagotype includes the strains with the same set of plasmids. The work results create preconditions for the detailed study of the role of microbe factor in development and inhibition of tumours.