Pneumococcal prosthetic joint infection – A challenging diagnosis

Background: Prosthetic joint infection (PJI) is a relatively rare (~1%) but catastrophic complication of joint arthroplasty. It is commonly caused by Staphylococcus aureus. Streptococcus pneumoniae is mostly associated with respiratory tract infections, sinusitis and meningitis, but is occasionally involved in native joint septic arthritis in a small percentage of cases. Its role and pathogenicity in PJI is largely unknown currently. Case report: We report a case of hematogenous infection of a total knee replacement by Streptococcus pneumoniae from a concurrent chest infection. Culture and 16S PCR of a pre-operative joint aspirate and white cell CT SPECT were negative for the index patient, posing significant diagnostic challenges. The definitive diagnosis was only achieved from intraoperative sampling during emergency debridement prior to which antibiotic treatment had been interrupted. Conclusion: The patient was eventually cured after a two-stage revision of the prosthetic joint, combined with a 6-week course of intravenous ceftriaxone.