Kingella kingae Induced Septic Arthritis in the Knee Revealing an Unexpected Diagnosis of Multiple Myeloma, a Case Report.

Introduction: Kingella kingae has become an increasingly significant cause of osteoarticular infection in children under the age of 4. The bacteria is infrequent in adults. Previous reports have indicated its association with infections, primarily affecting immunocompromised individuals. Only a few cases of isolated septic knee arthritis in immunocompetent patients caused by K. kingae have been reported.

Case report: We present a case involving a 64-year-old male with an unremarkable medical history diagnosed with septic arthritis in the knee attributed to K. kingae. He was treated with antibiotic therapy and joint irrigation and discharged with outpatient follow-up on the 9th day. The diagnosis led to an unexpected finding of multiple myeloma prompting further treatment.

Conclusion: This case confirms that K. kingae can cause septic arthritis in adults and physicians and microbiologists should be alert to the possibility, especially in adults with an underlying disease.