Chronic osteomyelitis of the right thumb caused by Actinomyces radingae and Finegoldia magna: a case report and literature review.

BACKGROUND

Osteomyelitis of the hand is relatively uncommon and often results from penetrating trauma or postoperative infection. Rare pathogens such as Actinomyces radingae and Finegoldia magna pose diagnostic and therapeutic challenges due to their slow growth, frequent involvement in polymicrobial infections, and limited antibiotic susceptibility data.

CASE PRESENTATION: A 66-year-old male sustained a crush injury being caught in a door to his right thumb over two years prior, leading to repeated episodes of redness, swelling, pain, and restricted motion. Despite undergoing surgical intervention three months earlier at another hospital, his symptoms persisted. Radiography revealed cortical irregularity and surrounding soft tissue swelling of the distal phalanx. Magnetic resonance imaging revealed bone marrow edema of the distal phalanx and adjacent soft tissue inflammation, raising suspicion for underlying osteomyelitis in the appropriate clinical context. Laboratory markers of infection were within normal limits. The patient underwent surgery including necrotic bone removal, extensor tendon reconstruction with muscle transposition, and nail bed debridement. Intraoperative findings included purulent drainage, nail deformity, and tendon necrosis. Metagenomic next-generation sequencing (mNGS)of bone tissue identified Actinomyces radingae (8,019 reads) and Finegoldia magna (4,223 reads). Based on the chronic clinical course, imaging findings, intraoperative evidence of necrotic bone, and pathogen identification by metagenomic next-generation sequencing, a diagnosis of chronic osteomyelitis of the distal phalanx was established. Postoperatively, the patient received ertapenem (1 g QD) with good clinical response.

CONCLUSION

This case highlights the importance of considering uncommon pathogens in chronic post-traumatic hand infections and demonstrates the utility of mNGS in identifying atypical bacteria, enabling targeted therapy and improved outcomes.