Antimicrobial resistance in respiratory tract pathogens: Results of an international surveillance study

An international surveillance study was performed to assess the resistance patterns among respiratory tract pathogens during the winter of 1997-1998. The pathogens studied included Streptococcus pneumoniae, Haemophilus influe nzae and Moraxella catarrhalis. The antibiotics tested included five beta-l actams (penicillin, ampicillin, amoxicillin, amoxicillin-clavulanic acid, c efuroxime axetil and ceftriaxone), two macrolides (azithromycin and clarith romycin), one sulfonamide (trimethoprim-sulfamethoxazole), one glycopeptide (vancomycin) and one fluoroquinolone (levofloxacin). A total of 11,502 iso lates were tested from nine countries, using microdilution susceptibility t ests as recommended by National Committee for Clinical Laboratory Standards (NCCLS) guidelines. The susceptibility rates varied greatly around the wor ld. Ninety percent of M. catarrhalis isolates produced beta-lactamase, maki ng them resistant to ampicillin. beta-Lactamase production by H. influenzae ranged from 5% in Germany to 34% in the USA (mean 17.5%). Of the S. pneumo niae isolates, 32.8% had some resistance to penicillin, but this ranged gre atly from 7.8% in Germany to 66.5% in France. Penicillin resistance in S. p neumoniae was associated with resistance to other beta-lactams, macrolides and sulfonamides, but not to levofloxacin or vancomycin. All isolates of H, influenzae and M. catarrhalis were susceptible to levofloxacin. Results of this study support the conclusion that these three respiratory tract patho gens are becoming more resistant to selected antimicrobials, and that the l evel of resistance in these isolates to the antimicrobials varies greatly f rom one country to another. Copyright (C) 2000 S. Karger AG, Basel.