Complicated septic arthritis of the sternoclavicular joint due to Bacteroides fragilis in a healthy middle-aged woman; A case report and literature review.

INTRODUCTION

Amongst bone and joints infections, native joints septic arthritis is uncommon, and involvement of the sternoclavicular joint (SCJ) is rare. Bacteroides fragilis is an unusual cause of septic arthritis in general and involvement of the SCJ in even more unusual. In the presented case report, we describe the clinical, radiological, microbiological and genomic evaluation of a healthy middle-aged woman who presented with SCJ septic arthritis secondary to Bacteroides fragilis.

CASE PRESENTATION: A 48-year-old lady presented with pain and swelling of the right upper chest accompanied by fever for 10 days. Upon initial assessment, she was febrile with a large area of tender swelling overlying the right sternoclavicular joint (SCJ). Radiological evaluation with a CT scan revealed features of SCJ septic arthritis with local complications of abscess formation with surrounding myositis. Urgent abscess drainage and washout of the SCJ was necessary to control local complications, however anaerobic cultures of the fluid were negative after 14 days of incubation. Anaerobic blood cultures grew sensitive Bacteroides fragilis after 5 days of incubation, while genomic studies from the fluid confirmed the same organism. The patient was treated with a total of 6 weeks antimicrobial therapy with clinical and radiological improvement.

CONCLUSION

SCJ septic arthritis is rare and infection secondary to Bacteroides fragilis is also rare. Hematogenous seeding and extension from locally infected sites are the most common causes. Prompt clinical, biochemical, microbiological and radiological evaluation is mandatory for safe outcomes. Treatment entails a combination of medical and surgical management in the form of appropriate antimicrobial therapy, surgical drainage, and debridement.