[Comparative study of apramycin-resistant microorganisms isolated from man and animals]. / Sravnitel'noe izuchenie apramitsinustoichivykh mikroorganizmov, vydelennykh ot cheloveka i zhivotnykh.

Apramycin-modifying strains isolated from pigs with coli bacteriosis, from humans and hospital environment were studied comparatively. Production of enzymes modifying the aminoglycoside was estimated with the radioactive cofactor procedure. E. coli isolates from the animals were phenotypically resistant to apramycin and a number of other aminoglycosides. They produced acetyltransferase AAC(3)IV, phosphotransferase APH(3')(5"), APH(3") and other enzymes. Resistance of the strains to gentamicin was also conditioned by AAC(3)IV since these strains did not produce AAD(2") and AAC(6'). In the resistant strains of E. coli and their transconjugates there were detected plasmids with a relative molecular weight of 60-80 MD. Some of the belonged to the compatibility group I1, the others belonged to the compatibility group H1. Strains of S. marcescens, K. pneumoniae. K. oxytoca and S. aureus isolated from humans and hospital environment were sensitive to apramycin. Only isolates of P. aeruginosa were resistant to this antibiotic. However, all the isolates produced AAC(3)IV. Some of them additionally produced AAC(6'), an enzyme modifying amikacin, kanamycin and other antibiotics and not acetylating apramycin. Almost all the strains produced kanamycin- and streptomycin phosphotransferases. Possible coselection of strains resistant to apramycin and gentamicin using one of these aminoglycosides is discussed.

[Conjugation transfer of plasmid resistance to gentamycin and other antibiotics in clinical strains of Ps. aeruginosa]. / Kon"iugatsionnaia peredacha plazmidnoi ustoichivosti k gentamitsinu i drugim antibiotikam u klinicheskikh shtammov Ps. aeruginosa.

A possibility of conjugation transfer of the markers of the plasmid resistance to gentamicin and other antibiotics from 10 clinical strains of Ps. aeruginosa, isolated from burn patients to the recipient strain of Ps. aeruginosa PTO 629 Rfr was shown. The marker of gentamicin resistance was transferred to 100 out of 110 of the exconjugants, i.e. 86.2 per cent. The rate of the conjugation transfer in the crosses between the clincal strains of Ps. aeruginosa and the recipient strain PTO 629 Rfr with respect to the gentamicin marker was about 10--7. The plasmid resistance markers in the clincal strains Ps. aeruginosa were transferred in various combinations. Transfer of the markers of resistance to streptomycin, carbenicillin, neomycin and combinations Sm, Nm and Sm, Nm, Cm was not achieved.

[Conjugational transfer of R factor RP1 in Ps. aeruginosa and the possibility of inhibiting this process with a series of substances]. / Kon"iugatsionnaia peredacha R-faktora RP1 u Ps. aeruginosa i vozmozhnost' ingibirovaniia étogo protsessa riadom veshchestv

It was shown that the conjugation system of Ps. aeruginosa PAO 2604 X PTO 629 rifr used for transfer of the plasmid markers of R-factor RPI was a convenient model for a number of genetic investigations (the rate of transfer of the antibiotic resistance markers was 2.2 X 10(-3) to 8.8 X 10(-5). 80.7 per cent of the exconjugants obtained from this crossing acquired all 3 resistance plasmid markers (carbenicillin tetracycline, neomycin). In 12 per cent of R+-exconjugants transfer of 2 or 1 resistance determinant of R-factor was observed. The use of the above conjugation system revealed the inhibitory effect of bonafton (an antiviral drug), acridine dyes (acrichin, metachrome orange), ethidium bromide and rifampicin. A possibility of intraspecies transfer of resistance plasmid markers was found in crosses Ps. aeruginosa PAO 2604 X X E. coli CSH--2 rifr and Ps. aeruginosa PAO 2604 X E. coli C600 rifr. Transfer of the resistance markers was observed in combinations of carbenicillin, tetracycline, neomycin (Cb, Tc, Nm), tetracycline (Tc) and carbenicillin (Cb).