Septic Polyarthritis by Staphylococcus aureus of "Unknown Origin".

More than 90% of septic arthritis cases are monoarticular. Joint infection can occur through several mechanisms such as hematogenous dissemination, by contiguity from adjacent infected soft tissue, surgical contamination, direct inoculation, or joint trauma.We report the case of a 69-year-old man admitted to our hospital with septic polyarthritis. The presented case is remarkable given its atypical presentation. The patient had no known risk factors for septic arthritis, comorbidities, or history of recurrent infections that could suggest some degree of immunosuppression. The atypical polyarticular involvement at presentation, the absence of sustained fever, and the good general condition of the patient delayed the diagnosis and treatment.