In vitro activity of moxifloxacin and other antimicrobials against respiratory pathogens

Background: Respiratory pathogens arte becoming increasingly resistant to a ntimicrobials. A new group of drugs, called respiratory quinolones have bee n synthesized to overcome this problem. Aim: To study the in vitro suscepti bility of respiratory pathogens to old and new antimicrobials. Material and Methods: Forty five strains of S pneumoniae, 44 strains of H influenzae, 2 1 strains of M catrrhalis, 10 strains of methicillin susceptible S aureus a nd 20 strains of methicillin resistant S aureus were studied. All were isol ated from community aquired respiratory infections during 1999. Minimal inh ibitory concentrations of moxifloxacin, amoxicilin, amoxicilin/clavulanic a cid, clarithromycin, azithromycin, ciprofloxacin and levofloxacin were dete rmined using the Etest method. Betalactamase production by H influenzae and M catarrhalis was also studied. Results: S pneumoniae strains were 100% su sceptible to quinolones contrimoxazole, 2% were resistant to macrolides, 11 % were resistant to amoxicilin/clavulanic acid and 47% were resistant to ce furoxime. H influenzae was 100% susceptible to quinolones, azithromycin and amoxicillin/clavunanic acid. There was a 53% resistant to macrolides, 14% resistant to amoxicilin/clavulanic acid, 20% to cefuroxime and 30% to cotri moxazole. Methicilline susceptible S aureus was susceptible to all antimicr obials and methicillin resistant S aureus was resistant to all. Conclusions : Moxifloxacin and the new respiratory quinolones can be useful in the trea tment of respiratory infections (Rev Med Chilie 2000; 128: 1319-26).