[Use of fluoroquinolones in intensive care units in a multi-drug-resistance era]

Despite the high level of antibiotic resistance in ICUs, fluoroquinolones remain the most frequent utilized antibiotic in these settings. Since the discovery of this class of antibiotics several mechanisms have been identified as responsible for resistance to fluoroquinolones and more recently a new one have been studied which is responsible for transferable resistance, which acts by means of an enzymatic inactivaction affecting only some members of the fluoroquinolones class. In fact, the cr variant of the gene aac(6)-Ib translates an aminoglycosides acetiltrasferases which confers a reduced susceptibility to those fluoroquinolones carrying this substrate, as ciprofloxacin and norfloxacin, but not to others such as levofloxacin. It is therefore interesting to speculate that the use of levofloxacin could avoid the development of resistance in those bacteria presenting this enzyme but not in those carrying a Qnr gene. The application of these new aspects of molecular biology in the clinical practice together with the knowledge of the risk factors could in the future contribute to reduce the development of antibiotic resistance. The ID consultation, the use of practical and reliable guidelines, the use of antibiotic association based on local epidemiology would represent further strategies to minimize the antibiotic resistance development optimizing the therapeutic choice.