Article in Japanese

Changes in the antimicrobial susceptibility of Streptococcus pneumoniae isolated from nasopharyngeal cultures of pediatric hospitalized patients between 2001 and 2010

Hisamitsu TAMAKI, Kei KOMIYA, Tae OMORI, Masahiro ITO, Masahiro OTSUKA

Changes in the antimicrobial susceptibility of Streptococcus pneumoniae isolated from nasopharyngeal cultures were studied in pediatric hospitalized patients between January 2001 and December 2010. In this study, we divided 2001-2010 into two groups 2001-2005 and 2006-2010. In 2006-2010, as compared with 2001-2005, susceptibility of penicillin G (PCG) was improved. The proportion of penicillin susceptible Streptococcus pneumoniae (PSSP; MIC range of PCG, ≤ 0.06 μg/ml) was increased, and penicillin resistant Streptococcus pneumoniae (PRSP; MIC range of PCG, ≥ 2 μg/ml) was decreased. In 2001-2005 proportions of PSSP and PRSP were respectively 15% and 45%; in 2006-2010 were 40% and 30%. In 2001-2005 50% of minimum inhibitory concentration (MIC₅₀) and MIC₉₀ of PCG were respectively 1 μg/ml and 4 μg/ml; in 2006-2010 were 0.25 μg/ml and 2 μg/ml. Cefotaxime (CTX) and meropenem (MEPM) were most susceptible, however related to susceptibility of PCG; MICs of CTX and MEPM to PRSP were higher than to PSSP. Susceptibilities of vancomycin (VCM) and erythromycin (EM) were unrelated to PCG. Susceptibility of VCM was susceptible to all strains, but that of EM was resistant to almost of all strains. As a result of this study, MIC₉₀ of PCG (2 μg/ml) to Streptococcus pneumoniae in 2006-2010, we recommend using parenteral synthetic penicillins to treat pediatric patients with pneumococcal respiratory infections.

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Department of Pediatrics, Tokyo Metropolitan Bokuto Hospital

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Received	April 21, 2011
Accepted	August 2, 2011

23 (4)：407─412,2012