[Properties of the R plasmids of Sh. flexneri strains isolated in Bulgaria]

The study of 3,237 Sh. flexneri strains isolated in Bulgaria revealed that 50.72% of them were resistant to antibiotics. 95.88% of the antibiotic-resistant strains were found to have R factor of incompatibility groups F, I or N. The plasmids of incompatibility group F had the property fin+, and the plasmids of groups I and N had the property fin-. R plasmids were divided into 4 groups by their ability for phage restriction.