RESUMEN
Background: Respiratory pathogens are becoming increasingly resistant to antimicrobials. A new group of drugs, called respiratory quinolones have been synthesized to overcome this problem. Aim: To study the in vitro susceptibility of respiratory pathogens to old and new antimicrobials. Material and methods: Forty five strains of S pneumoniae, 44 strains of H influenzae, 21 strains of M catarrhalis, 10 strains of methicillin susceptible S aureus and 20 strains of methicillin resistant S aureus were studied. All were isolated from community acquired respiratory infections during 1999. Minimal inhibitory concentrations of moxifloxacin, amoxicilin, amoxicilin/clavulanic acid, clarithromycin, azithromycin, ciprofloxacin and levofloxacin were determined using the Etest method. Betalactamase production by H influenzae and M catarrhalis was also studied. Results: S pneumoniae strains were 100 percent susceptible to quinolones and cotrimoxazole, 2 percent were resistant to macrolides, 11 percent were resistant to amoxicilin/clavulanic acid and 47 percent were resistant to cefuroxime. H influenzae was 100 percent susceptible to quinolones, azithromycin and amoxicilin/clavulanic acid. There was a 53 percent resistance to cotrimoxazole, 21 percent to amoxicilin, 9 percent to clarithromycin and 7 percent to cefuroxime. M catarrhalis was 100 percent susceptible to quinolones and 100 percent resistant to amoxicilin, 5 percent resistant to macrolides, 14 percent resistant to amoxicilin/clavulanic acid, 20 percent to cefuroxime and 30 percent to cotrimoxazole. Methicilline susceptible S aureus was susceptible to all antimicrobials and methicillin resistant S aureus was resistant to all. Conclusions: Moxifloxacin and the new respiratory quinolones can be useful in the treatment of respiratory infections