Antimicrobial susceptibility of 1,422 Haemophilus influenzae isolates fromrespiratory tract infections in Spain. Results of a 1-year (1996-97) multicenter surveillance study

A Haemophilus influenzae multicenter antimicrobial susceptibility surveilla nce was carried out. An overall beta-lactamase production rate of 25.7% was found, with significant differences between hospitals ranging between 7.9 and 47.9%. Presumable intrinsic resistance was found in 4.6% of strains. No differences in susceptibility were observed between beta-lactamase positiv e and beta-lactamase negative strains for all antibiotics, except for penic illin, amoxicillin and cefaclor, A higher prevalence of resistance was foun d for clarithromycin vs azithromycin (22.6 vs 0.7%). Differences in all the se factors make surveillance essential as a guideline for empiric treatment in community-acquired respiratory tract infections.