Development of gentamicin resistance in gram-negative bacteria in Czechoslovakia and correlation with its usage.

Widespread use of gentamicin in Czechoslovakia began in 1975 when it became more available, although its use remained restricted until 1986. Starting in 1980 a remarkable increase in gentamicin resistance was observed in Pseudomonas aeruginosa, Klebsiella, Enterobacter and several Proteus species, especially Proteus rettgeri. A large proportion of gentamicin-resistant strains came from the urine of hospitalized patients. In spite of infection control measures and restrictive antibiotic policy, gentamicin resistance has increased over the last years. In 1985 gentamicin resistance of bacteria in Czechoslovakia represented 18.2% and was higher than in Austria or the Federal Republic of Germany, for example, but lower than in Hungary, France, Greece and Italy. The usage of gentamicin has also increased. During the years 1982-1987 gentamicin usage in Czechoslovakia increased by one-half. In a representative collection of 69 gentamicin-resistant Gram-negative strains from seven regions of Czechoslovakia, the mechanisms of resistance to gentamicin, netilmicin, tobramycin and amikacin were studied. Production of acetyltransferases (AAC) and adenylyltransferases (ANT) was observed in 84% of strains. The majority of isolates produced AAC(3) enzymes (55%); production of ANT(2") represented the second most observed resistance mechanism (35%); only 14% of isolates produced AAC(6'). This resistance pattern correlates with patterns reported recently for Central and Southern Europe. Due to dissemination of plasmids coding for the AAC(3)-II enzyme, the majority of Czechoslovak gentamicin-resistant Gram-negative strains were also tobramycin- (87%) and netilmicin-resistant (68%). Amikacin remains the most effective aminoglycoside against multiresistant bacterial strains.