[Genetic determinants of resistance to antibiotics in Pseudomonas bacteria]

Seven hundred and eighty nine drug resistant strains of Pseudomonas isolated in hospitals, from antibiotic production sewage and mine soils were studied in experiments on colony hybridization with the use of 32P-labeled plasmid DNA fragments containing various antibiotic resistance genetic determinants. The genes controlling production of aminoglycoside-3'-phosphotransferase, aminoglycoside-3'-adenilyl transferase, type I dihydropteroate synthetase (DHPS I) and DHPS II were detected in the strains of all the ecological niches. More than 90 per cent of the clinical strains hybridized with the samples containing these genes, though in the soil strains the main mechanisms of streptomycin and sulfanilamides resistance were probably controlled by the other nonhomologous genetic determinants studied. The gene controlling production of aminoglycoside-3'-phosphotransferase II was detected in the strains isolated both in the hospitals (49 per cent) and from the sewage (45 per cent), while the gene of aminoglycoside-3'-phosphotransferase I was detected only in the population of the clinical strains (52 per cent). The majority of the tetracycline resistant strains isolated in the hospitals and from the sewage hybridized with the samples containing the classes A and C tetracycline resistance genetic determinants. In the soil strains the genetic determinants of the main tetracycline resistance mechanism(s) were not homologous to those of classes A, B and C. Resistance of the strains to trimetoprine was as a rule determined by the genes of type II dihydrofolate reductase.