[Incidence of conjugated R plasmids in E. coli strains isolated from birds with colisepticemia].

Studied were a total of 143 strains of Escherichia coli, isolated from birds affected with coli septicaemia, with special reference to the presence of conjugative R-plasmids. It was found that 57 of the strains could not be tested on E. coli C-600, and the carrying of R-plasmids with the remaining 86 strains reached 65.11 per cent. The markers of kanamycin, sulphatiazol, and neomycin were transmitted in a highest percent (63.95, 53.47, and 45.43, respectively). The level of the resistance transferred proved close or comparable to that of the field strains. It was concluded that the conjugative R-plasmids were widely occurring with Escherichia coli strains that were pathogenic for birds. This should be taken into consideration when using chemotherapeutic agents with birds.