A comparison of side effects of levofloxacin to other agents concerning the ecological and microbiological effects on normal human flora

The safety of levofloxacin was compared to that of non-fluoroquinolone alte rnatives used for respiratory tract infections. Results from five randomise d controlled trials revealed that the incidence of any adverse events possi bly associated with levofloxacin ranged from 5.8% to 22.7%, whereas that of comparators (ceftriaxone, cefuroxime axetil, clarithromycin and amoxicilli n-clavulanic acid) ranged from 8.5% to 39.3%. The rate of adverse drug reac tions (ADRs) was lower for levofloxacin in all trials. The most common adve rse events for all agents tended to be gastrointestinal in nature. Levoflox acin was associated with a mild effect on the normal microflora, reaching a maximum at four days of therapy, with complete recovery being achieved by seven days post-therapy. No colonisation with resistant strains was observe d during the period of levofloxacin therapy. Amoxicillin-clavulanic acid ad ministration selected for resistant strains of Enterobacteriaceae, and ampi cillin administration was associated with both resistant strains of Enterob acteriacae as well as Candida spp. Ceftriaxone selected resistant strains o f Clostridium difficile and Candida spp. Thus, microflora effects favoured levofloxacin over all of the agents tested, including macrolides and tetrac yclines. These results confirm that the ecological impact of levofloxacin i s markedly less than that associated with non-fluoroquinolone comparators. Copyright (C) 2001 S. Karger AG, Basel.