[Mechanisms of R-factor coded resistance (author's transl)].

The prevalence of resistance factors (R-factors) has become a serious threat to the chemotherapeutic armament of modern medicine. These extrachromosomal elements exert their effects by supplying the harbouring bacterial cell with the genetic information for detoxifying enzymes, for the expression of biochemical mechanisms which effectively prevent antibiotic molecules from reaching their target or for the synthesis of resistant target molecules. The genes which are responsible for these effects were recently shown to reside on "transposons", genetic entities which can recombine with various DNA moieties, like plasmids, bacterial chromosomes, or the genome of bacteriophages. The transposon nature of most resistance determinants provide the bacterial world with an enormous flexibility in the response to antibiotic selection pressure. It is an absolute requirement for the future to stop further spread of R-factors by reducing the selection pressure. Doctors will have to apply antibiotics more selectively, and in animal breeding and growth promotion only those drugs should be used which are never prescribed for humans. Moreover, pharmaceutical research should be directed towards the development of compounds acting on R-factors or on their enzyme systems.