Prosthetic Joint Infection Caused by <i>Streptococcus pneumoniae</i> Serotype 15F: A Rare Manifestation of an Emerging Non-Vaccine Serotype

Prosthetic joint infection (PJI) caused by Streptococcus pneumoniae is rare, particularly in the absence of bacteremia. This case report describes a 69-year-old Japanese woman with a history of follicular lymphoma and bilateral total hip arthroplasty who developed a right periprosthetic abscess caused by S. pneumoniae. This was an unusual presentation as the patient lacked typical respiratory or neurological symptoms or bacteremia. The causative strain was identified as serotype 15F, a non-vaccine serotype (NVT) not covered by current pneumococcal vaccines. This case highlights serotype replacement, where NVT infections emerge because of widespread vaccination, potentially presenting atypically and exhibiting antibiotic resistance.