A Rare Case of Chronic Osteomyelitis of the Left Humerus Caused by <i>Aerococcus viridans</i>

Abstract

Introduction: Aerococcus viridans is a rare Gram-positive coccus and an opportunistic pathogen primarily associated with healthcare-acquired infections, including neonatal meningitis and urinary tract infections. Its involvement in chronic osteomyelitis is exceptionally uncommon, and its detection may be hindered by faster-growing organisms such as Staphylococcus aureus, resulting in underdiagnosis or misclassification as a contaminant. This report describes a rare case of chronic osteomyelitis caused by A. viridans and highlights the importance of accurate microbiological identification of low-virulence pathogens in chronic bone infections. Case Presentation: A 59-year-old woman with type 2 diabetes mellitus and chronic osteomyelitis of the left humerus underwent surgical debridement and implantation of a vancomycin-impregnated bone cement chain. Microbiological identification and antimicrobial susceptibility testing were performed, and targeted antimicrobial therapy was administered according to the susceptibility results. A. viridans was identified as the causative organism. The patient was successfully treated with surgical debridement, implantation of vancomycin-impregnated bone cement, and targeted antimicrobial therapy. Conclusions: Aerococcus viridans should be regarded as a potential pathogen, rather than merely a contaminant, in chronic bone infections. Accurate microbiological identification and susceptibility-guided antimicrobial therapy are essential for appropriate diagnosis and management. To our knowledge, this is the first reported case of chronic osteomyelitis caused by A. viridans.