Antimicrobial susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis collected from five centers in Brazil, 1997-98

Objective To assess the susceptibility of the : key respiratory pathogens S treptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis t o antimicrobial agents used to treat respiratory tract infections. Methods isolates were collected from five centers in Brazil during 1997-98, and susceptibility testing was conducted at a central laboratory according to National Committee for Clinical Laboratory Standards criteria. Results Of the 359 Streptococcus pneumoniae isolates tested, 77% were susce ptible, 19% were intermediate and 4% were resistant to penicillin. The susc eptibility of S. pneumoniae to other beta-lactams and macrolides was greate r than 90%, but cotrimoxazole was active against only 48% of the: isolates, The prevalence of susceptible isolates was 100.0% for vancomycin and 99.7% for levofloxacin. beta-Lactram, macrolide, and cotrimoxazole activities we re negatively associated with penicillin resistance. Of the 219 isolates of Haemophilus influenzae tested, 11% produced beta-lactamase and 11% were no t susceptible to ampicillin. Nearly all H. influenzae isolates were suscept ible to all other drugs, except cotrimoxazole (47% susceptibility). Of the 52 Moraxella catarrhalis isolates, 98% produced beta-lactamase, and the MIC of all drugs was less than or equal to 4 mg/L, with the exception of amyic illin, where the: MIC90 was > 8 mg/L. Conclusions When these data are compared with previous reports, our finding s suggest that the prevalence of pneumococci that are resistant to agents s uch as penicillin and cotrimoxazole may be increasing in Brazil, which high lights the need to continue surveillance programs.