Antibiotic Susceptibility Patterns of Streptococcus pneumoniae in China and Comparison of MICs by Agar Dilution and E-Test Methods

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Abstract
Beta-lactam resistance by Streptococcus pneumoniae is becoming a significant threat to public health worldwide. However, data concerning antibiotic susceptibility patterns in China have not been published. In this study, a total of 79 clinical isolates and 244 nasopharyngeal isolates of S. pneumoniae were recovered between June and November 1997 in Beijing. The agreement between the MICs (±1 log 2 dilution) of penicillin and ceftriaxone obtained by the agar dilution and E-test methods for the 79 clinical strains was very good (97.5 and 93.7%, respectively). Of these 79 strains, 9 (11.4%) were intermediate and 2 (2.5%) were resistant to penicillin. Of the 244 nasopharyngeal strains, 32 (13.1%) were intermediate and 3 (1.2%) were resistant to penicillin. The total of 277 penicillin-susceptible clinical and nasopharyngeal isolates of Streptococcus pneumoniae were 100% susceptible to amoxicillin-clavulanic acid, cefuroxime, ceftriaxone, and cefotaxime. In the 35 penicillin-intermediate and -resistant nasopharyngeal strains, elevated MICs of amoxicillin-clavulanic acid, cefuroxime, ceftriaxone, and cefotaxime were seen for ≤4 isolates. Of 244 nasopharyngeal isolates, the overall percentages of tetracycline, erythromycin, chloramphenicol, ofloxacin, and trimethoprim-sulfamethoxazole resistance were 87.6, 74.0, 47.8, 3.7 and 63.3, respectively. Vancomycin and rifampin resistance were not detected. These findings demonstrate that the rate of penicillin-resistant pneumococci is relatively low in China compared to those of other Asian countries. Resistance to non-beta-lactams was much higher than to beta-lactams. The E-test and agar dilution methods appeared to be comparable in identifying resistant strains.