Chronic Fibular Osteomyelitis Caused by Schaalia turicensis: A Case Report and Literature Review.

BACKGROUND: Schaalia turicensis (previously classified as Actinomyces turicensis) may lead to actinomycosis, typically presented as a chronic, granulomatous infection marked by suppuration and sinus tract formation, with a propensity for recurrence. This report details a rare case of chronic post-traumatic osteomyelitis attributable to S. turicensis. CASE PRESENTATION: A 57-year-old woman was presented with a four-year history of recurrent redness, swelling, and ulceration of the left lower leg after surgical intervention. Debridement of the lesion was performed by orthopedists. Metagenomic next-generation sequencing (mNGS) analysis of intraoperative tissue samples revealed S. turicensis and penicillin therapy was initiated accordingly. Subsequent culture results identified Actinomyces species and methicillin-resistant Staphylococcus epidermidis (MRSE). The antibiotic regimen was adjusted to clindamycin, leading to clinical improvement and eventual discharge. CONCLUSION: This case underscores the diagnostic dilemma posed by indolent pathogens like S. turicensis in chronic post-surgical osteomyelitis. mNGS provided a rapid and precise microbiological diagnosis, directly informing critical therapeutic decisions.