Occurrence of aminoglycoside-modifying enzymes in resistant strains of enterobacteria and Pseudomonas aeruginosa from several countries

Abstract

A series of aminoglycoside-resistant isolates of Enterobacteriaceae and Pseudomonas aeruginosa originating from the hygiene-centres in Frankfurt/M, Berne and Bratislava have been examined for the presence of aminoglycoside inactivating enzymes. Nearly all of the strains tested were resistant to gentamicin, sissomicin, netilmicin, tobramycin as well as eight further aminoglycosides. Results from radioenzymatic assays strongly suggested the presence of at least two aminoglycoside-transferases in 15 strains examined. From the total amount ten strains produced aminoglycoside-acetylating enzymes. The presence of 3-N-acetyltransferase was observed in four strains whereas in two strains the occurrence of 6′-N-acetyltransferase was noticed. In four strains a simultaneous production of both mentioned acetyltransferases may be assumed from the results of experiments performed at different pH values and from the results of microbiological inactivation. Nine strains produced 2″-O-nucleotidyltransferase. All these strains produced also streptomycin adenylyltransferase. Streptomycin phosphotransferase was found in two streptomycin-resistant strains. Aminoglycoside-3′-O-phosphotransferase was found in eight strains resistant to kanamycin and neomycin. Both acetylating and adenylylating modification mechanisms were found in most of the strains examined, contributing probably to the extremely high levels of resistance to gentamicin.