Nationwide survey of the development of drug-resistant pathogens in the pediatric field: drug sensitivity of Streptococcus pneumoniae in Japan

We evaluated the resistance to 20 different antibacterial agents of 362 clinically isolated strains of Streptococcus pneumoniae accumulated from October 2000 to July 2001 (phase 1) and of 332 different strains accumulated from January to June 2004 (phase 2), from institutions throughout Japan that participated in the surveys carried out by the Drug-Resistant Pathogen Surveillance Group in Pediatric Infectious Disease. In phase 1, the proportions of penicillin-sensitive S. pneumoniae (PSSP), penicillin-insensitive S. pneumoniae (PISP), and penicillin-resistant S. pneumoniae (PRSP) were 35.4%, 34.8%, and 29.8%, respectively, and the proportions were almost the same in phase 2: 33.1%, 37.0%, and 29.8%, respectively. Comparison of the MIC90 values of the antibacterial agents for PRSP in phase 1 and phase 2 revealed that these values for cefditoren, cefpodoxime, cefdinir, faropenem, ceftriaxone, cefotaxime, meropenem, and vancomycin increased by twofold to fourfold during the 3 years between phase 1 and phase 2. However the MIC90 of rokitamycin increased more than fourfold. The proportion of S. pneumoniae that were PISP + PRSP remained almost constant over the 3 years between phase 1 and phase 2. The background factors of patient age, previous administration of antibacterial agents, and attendance at a day nursery were examined; we found that in phase 1, the proportion of PISP + PRSP was significantly higher than that of PSSP in patients under 4 years old who had previously received antibacterial agents, but no significant differences were found in any of these background factors in the phase 2 survey. No significant difference was found in the proportions of penicillin-resistant bacteria according to whether or not the child had attended a day nursery.