[A case of empyema in a previously healthy child caused by Streptococcus pneumoniae serotype 1].

A 6-year-old boy admitted for empyema was found to have Streptococcus pneumoniae serotype 1 isolated from both blood and drainage fluid. The organism had no mutated genes encoding penicillin-binding proteins and was susceptible to all antibiotics. Empyema caused by S. pneumoniae serotype 1 in childhood has not, to our knowledge, been reported in Japan. In many countries where nanovalent pneumococcal conjugate vaccine (PCV7) has been introduced, serotype 1 frequency is especially high and empyema prevalence has increased. Monitoring of this S. pneumoniae serotype may be more important in invasive pneumococcal disease (IPD) than previously thought, especially in empyema, even after PCV7 is introduced in Japan.