EN
Shortly after the introduction of fluoroquinolones into human and animal therapy an acquired resistance to these compounds was described in many bacterial species. The primary type of the resistance generally involves multiple point mutations in the genes encoding the quinolone target enzymes: gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE). The frequency of occurrence of Salmonella strains conferring quinolone resistance has recently increased significantly. Moreover, novel plasmid-mediated resistance mechanisms that can spread horizontally were reported. These include the production of enzyme protecting peptides encoded by several alleles of qnr gene (qnrA, qnrB, qnrS, qnrD) and their variants, quinolone efflux pump (qep), and finally ciprofloxacin modification by a variant of aminoglycoside acethyltransferase (aac(6’)-Ib-cr). The paper presents the background of resistance mechanisms as well as the occurrence and global spread of quinolone resistant Salmonella.