Corynebacterium striatum as a rare cause of septic arthritis in a native joint: A case report and review of the literature.

Septic arthritis commonly occurs due to gram-positive cocci and usually presents as acute monoarticular swelling and tenderness, often associated with systemic signs of sepsis. In rare scenarios, Corynebacterium striatum, a gram-positive bacillus, can cause septic arthritis. We present a rare case of native joint septic arthritis caused by C. striatum in an immunocompetent patient. A 74-year-old man with history of ESRD receiving HD presented with hematuria. He was found to have anemia and pyuria and was admitted for management of hematuria and UTI with ceftriaxone. Five days later, he developed new persistent fever and worsening leukocytosis, while receiving antibiotics. Examination revealed right knee swelling, erythema, and tenderness, with decreased range of motion. X-ray showed joint effusion for which he underwent right knee arthrocentesis and aspiration. Synovial fluid culture grew C. striatum, initially disregarded as a contaminant. Repeat cultures again grew C. striatum. He was treated with IV vancomycin and oral colchicine along with arthroscopic irrigation and debridement, and discharged on a 4-week course of vancomycin. C. striatum is typically a considered pathogen in immunocompromised individuals; however, emerging reports describe its role in infections among immunocompetent hosts. While C. striatum remains a rare cause of native joint septic arthritis, its isolation in multiple specimens in the appropriate clinical context should prompt clinicians to consider a true infection rather than contamination. Prompt identification and appropriate management is key to improving patient outcomes. Susceptibility testing helps guide targeted treatment for this emerging pathogen with increasing multi-drug resistance.