Background: Streptococcus pneumoniae (S. pneumoniae) is one of the most clinically significant pathogens with emerging antibiotic resistance, and most of the highly resistant strains to penicillin were clone related all over the world. This study was undertaken to investigate the antibiotic-resistant pattern and the genetic background of S. pneumoniae isolated from children in Hangzhou, China.

Methods: The sensitivities of 323 strains of S. pneumoniae to 9 different antibiotics were determined in vitro with the Kirby-Bauer diffusion method. Minimal inhibitory concentrations (MICs) of penicillin, cefotaxime and erythromycin were determined with the E-test method. Genetic types were analyzed with BOX-PCR.

Results: Among the 323 strains isolated from children between August 2001 and July 2002, 136 strains (42.1%) were sensitive to penicillin, while 57 strains (17.7%) were penicillin-resistant isolates. MICs for penicillin ranged from 0.012 μg/ml to 4.0 μg/ml. Three hundred and sixteen (97.8%) isolates were sensitive to cefotaxime with the MICs ranging from 0.008 μg/ml to 1.0 μg/ml. Seven isolates (2.2%) showed intermediate MICs with 2.0 μg/ml. Remarkably high levels of resistance were observed in 90.7% and 87.6% of the strains being resistant to erythromycin and tetracycline, respectively. Resistance to trimethoprim-sulfamethoxazole and choloromycetin was found in 48.6% and 14.9% of the strains. One hundred and ninety-seven strains (61.0%) were multi-resistant pneumococci, and most of them were cross-resistant to trimethoprim-sulfamethoxazole, erythromycin and tetracycline. Two strains (0.6%) were resistant to rifampin, and none was resistant to vacomycin and ofloxacin. On the basis of BOX-PCR typing of penicillin resistant Streptococcus pneumonia, no dominant fingerprinting pattern could be identified among clinical isolates, whereas the banding patterns were always similar to or identical among the isolates from healthy individuals or from the same specimen / patient at different times.

Conclusions: The antibiotic-resistance of pneumococci has been found to be high in Hangzhou, but third-generation cephalosporins are still the first option against penicillin-resistant Streptococcus pneumonia. The penicillin-resistant pneumococci might be one of geographic origins in the Hangzhou region, and one child could be infected or colonized by more than one pneumococci clone at the same time or at different times.