The role of R-plasmids in hospital strains of Proteus

The antibiotic sensitivity of Proteus strains isolated between 2017 and 2021 was investigated. A total of 85 Proteus strains were analyzed, revealing the widespread presence of poly-resistant forms of this pathogen. The examination of the antibiotic susceptibility spectrum in these strains demonstrated that those isolated from 2017 to 2021 exhibited similarities in their resistance profiles, with an expanding range of resistance observed towards gentamycin, kanamycin, carbenicillin, and others. The study identified that hospital-derived Proteus strains possess both conjugative and non-conjugative plasmids, distributed across different compatibility groups. It was shown that 55% of Proteus strains have conjugative R-plasmids, determining stability to streptomycin, gentamycin, carbenicillin, tetracycline, chloramphenicol, refer to T, J, M, N groups of incompatibility and have molecular masses 53.0; 33.0; 38.0; 49.0 MDa, respectively. In Proteus strains plasmids belonging to Inc-PI group of incompatibility were found. Furthermore, non-conjugative R-plasmids were identified in Proteus strains, conferring stability to tetracycline and streptomycin, with molecular masses of 7.2 and 5.8 MDa, respectively. Thus, the investigation of Proteus strains isolated in two clinics highlighted the participation of both conjugative and non-conjugative resistance plasmids in the development of hospital-associated Proteus strains.