MULTICENTER IN-VITRO COMPARATIVE-STUDY OF FLUOROQUINOLONES AFTER 4 YEARS OF WIDESPREAD CLINICAL USE

In vitro activities of ciprofloxacin, fleroxacin, lomefloxacin, ofloxa cin, and seven other oral antimicrobials including amoxicillin-clavula nic acid (A/C), oxacillin, cefaclor, cefixime, cefuroxime, erythromyci n, and trimethoprim-sulfamethoxazole (T/S) were evaluated against 1708 fresh bacterial isolates from four hospital laboratories similar to 4 years otter the introduction of ciprofloxacin. T/S and ofloxacin had the lowest MIC(90)s and greatest percentage of susceptible strains ove rall, followed by the other three quinolones. Quinolones were the most active drugs tested against Gram-negative bacteria, with little varia tion in the activity among the four compounds against most species. Q uinolone resistance was detected to some degree in the majority of Gra m-negative species tested, with Pseudomonas, Acinetobacter, Xanthomona s, and Providencia demonstrating the highest percentage of resistant s trains. Ofloxacin and ciprofloxacin were relatively more active agains t Gram-positive bacteria than were fleroxacin and lomefloxacin, but T/ S and A/C had more susceptible strains than any of the quinolones. Oxa cillin-resistant staphylococci, enterococci, land streptococci exhibit ed the least quinolone susceptibility. This study showed that while re sistance is developing among several previously susceptible bacterial species, quinolones remain important alternatives for the oral treatme nt of many types of infections. Actions to prevent or limit resistance will be important to maintain the viability of the quinolones as ther apeutic agents in both hospital and community environments.