QUINOLONE RESISTANCE IN PSEUDOMONAS-AERUGINOSA AND STAPHYLOCOCCUS-AUREUS - DEVELOPMENT DURING THERAPY AND CLINICAL-SIGNIFICANCE

This review focuses on published information on the experimental as we ll as clinical data on the emergence of quinolone resistant isolates. In the course of clinical use of fluoroquinolones, only a sporadic eme rgence of quinolone resistance has been noted. The resistant organisms emerged particularly in certain clinical settings where large numbers of organisms frequently causing chronic infections are present and/or in loci where quinolone concentrations may not be optimal. In terms o f occurrence in individuals, quinolone resistance has emerged most fre quently in hospitalized and nursing-home patients with identifiable ri sk factors. Epidemiological studies revealed that in nearly all the ca ses studied one or one predominating quinolone resistant clone was sel ected that was horizontally transmitted. Thus, the emergence of quinol one resistance is not due to an independent selection of resistant str ains in a number of patients, but to the clonal spread of one strain o nce it has acquired quinolone resistance. Therefore, the rate of quino lone resistance is very likely to be lower than reported.