The change of susceptibility of Streptococcus pneumoniae strains isolated from pediatric patients at Asahikawa Kosei Hospital between 2011 and 2015.

The susceptibility of 1578 Streptococcus pneumoniae strains isolated from pediatric patients at Asahikawa Kosei Hospital between 2011 and 2015 was tested to penicillin G (PCG), cefotaxime (CTX), ceftriaxone (CTRX), cefditoren (CDTR), meropenem (MEPM), erythromycin (EM) and levofloxacin (LVFX). Although no significant differences were observed, the percentage of strains with a minimal inhibitory concentration (MIC) of PCG of <0.1pg/mL increased from 55.5% (2011) to 64.0% (2015), whereas that of strains with MIC of ≥2μg/mL decreased from 14.8% to 9.5%. From 2011 to 2015, the percentage of strains with MIC ≤0.12ug/mL increased from 18.9% to 28.9% for CTX, from 20.5% to 30.2% for CTRX, from 29.2% to 40.9% for CDTR, and from 69.6% to 80.6% for MEPM. EM-resistant strains with MIC ≥22μg/mL accounted for as much as approximately 90% each year. One LVFX-resistant strain with MIC 8pg/mL has been detected each year since 2013.