Article in Japanese

A case of meningitis caused by capsular type 23A and genetically penicillin-resistant Streptococcus pneumoniae

Shugo Hirashima^1）, Yosuke Komatsu^1）, Hiroyuki Shimizu^2）, Koji Ozasa^1）, Hiroyuki Sakuma^1）, Nobuyuki Kikuchi^1）

We report a case of bacterial meningitis caused by Streptococcus pneumoniae serotype 23A （non-vaccine type ［NVT］） in a 3-year-old girl. The patient presented with fever, headache, and meningeal irritation signs; antimicrobial therapy was promptly initiated, and S. pneumoniae was later detected in both the blood and cerebrospinal fluid. Although antimicrobial susceptibility testing results indicated susceptibility to both cefotaxime and meropenem, no improvement was observed, and vancomycin was therefore added to the treatment regimen. Genetic analysis of penicillin-binding proteins （PBPs） associated with β-lactam resistance revealed that the strain had mutations in three PBP genes, and it was eventually identified as a penicillin-resistant S. pneumoniae ［genotype （g）］ （gPRSP） strain.
The introduction of pneumococcal conjugate vaccines has reduced the incidence of pneumococcal meningitis; however, the number of cases of meningitis caused by NVT pneumococci has increased recently. Moreover, these include those caused by gPRSP strains, some of which also show discrepancies between antimicrobial susceptibility test results and genetic antimicrobial resistance. Therefore, it is recommended that careful judgment be exercised when selecting antibiotics for meningitis treatment.

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1）Department of Pediatrics，Yokohama Rosai Hospital
2）Department of Clinical Laboratory，Fujisawa City Hospital

Key words	pneumococcal meningitis, non-vaccine type, pneumococcal conjugate vaccines, ppenicillin-resistant Streptococcus pneumoniae, antimicrobial susceptibility testing
Received	October 18, 2025
Accepted	March 8, 2026

38 (2)：151─156,2026