Extremely high incidence of macrolide and trimethoprim-sulfamethoxazole resistance among clinical isolates of Streptococcus pneumoniae in Taiwan

From January 1996 to December 1997, 200 isolates of Streptococcus pneumonia e recovered from 200 patients treated at National Taiwan University Hospita l were serotyped and their susceptibilities to 16 antimicrobial agents were determined by the agar dilution method. Sixty-one percent of the isolates were nonsusceptible to penicillin, exhibiting either intermediate resistanc e (28%) or high-level resistance (33%). About two-fifths of the isolates di splayed intermediate or high-level resistance to cefotaxime, ceftriaxone, c efepime, imipenem, and meropenem. Extremely high proportions of the isolate s were resistant to erythromycin (82%), clarithromycin (90%), and trimethop rim-sulfamethoxazole (TMP-SMZ) (87%), Among the isolates nonsusceptible to penicillin, 23.8% were resistant to imipenem; more than 60% displayed resis tance to cefotaxime, ceftriaxone, cefepime, and carbapenems; 96.7% were res istant to erythromycin; and 100% were resistant to TMP-SMZ. All isolates we re susceptible to rifampin and vancomycin. The MICs at which 50% and 90% of the isolates were inhibited were 0.12 and 1 mu g/ml, respectively, for cef pirome, and 0.12 and 0.25 mu g/ml, respectively, for moxifloxacin. Six sero groups or serotypes (23F, 19F, 6B, 14, 3, and 9) accounted for 77.5% of all isolates. Overall, 92.5% of the isolates were included in the serogroups o r serotypes represented in the 23-valent pneumococcal vaccine. The incidenc e of macrolide and TMP-SMZ resistance for S. pneumoniae isolates in Taiwan in this study is among the highest in the world published to date.