Antimicrobial susceptibilities of Streptococcus pneumoniae isolated from adult patients with community-acquired pneumonia in Japan

Background and objective:   Streptococcus pneumoniae ( S. pneumoniae ) is the most common pathogen associated with community-acquired pneumonia and its resistance to antimicrobials is a worldwide problem. The aim of this study was to investigate the current drug susceptibilities of S. pneumoniae isolated from adult patients with community-acquired pneumonia in Japan.
Methods:   S. pneumoniae strains isolated from adult patients with pneumococcal pneumonia from 10 institutions were collected prospectively between May 2003 and October 2004 and tested for drug susceptibilities. Clinical data were analysed and the risk factors for drug resistance investigated.
Results:   A total of 141 isolates of S. pneumoniae were analysed. Of these S. pneumoniae isolates, 46.1% had intermediate penicillin resistance and the minimum inhibitory concentration (MIC) occurring in the greatest number of isolates and MIC90 value was 2 μg/mL. The prevalence of resistance to macrolides was 80%, with the MIC90 values being greater than or equal to 16 μg/mL. Approximately 40% of the strains were resistant to oral third-generation cephems. Penicillin and erythromycin resistance were both associated with the pre-existing chronic disease states.
Conclusions:   The cephem and macrolide resistance of S. pneumoniae was higher than penicillin resistance in adult patients with community-acquired pneumococcal pneumonia in Japan. We recommend that bacterial identification and sensitivities are determined in areas where the macrolide resistance to S. pneumoniae is high.