Azelaic acid: a viewpoint by Susan Bershad.

BACKGROUND

Septic bursitis is mainly caused by Staphylococcus aureus and Streptococcus spp. However, patients with immunosuppression may develop infections caused by rare pathogens. Here, we describe a case of septic olecranon bursitis caused by Nocardia farcinica and provide a literature review of musculoskeletal infections caused by this pathogen.

CASE PRESENTATION: A male patient in his mid-70s with seronegative rheumatoid arthritis who was receiving methotrexate, low-dose prednisone, and golimumab experienced trauma to the elbow, followed by progressive painful swelling, slight erythema, and the formation of a fistula draining cloudy fluid over the subsequent two weeks. Culture of the aspirated bursal fluid yielded slow-growing yellow-pigmented colonies identified as Nocardia farcinica. Whole-genome sequencing confirmed the species without detecting any known virulence genes or resistance mutations. Clinical and radiological evaluation showed no signs of systemic dissemination. The patient underwent surgical bursectomy and received targeted antimicrobial therapy with oral trimethoprim/sulfamethoxazole. After 3 weeks, the patient developed a systemic allergic reaction, necessitating a switch to susceptibility-guided amoxicillin/clavulanate. Treatment was continued for 3 months, ultimately resulting in the complete and successful resolution of the bursitis.

CONCLUSION

This report highlights that it is important for clinicians to consider rare pathogens in immunosuppressed patients with bursitis, especially in those presenting with atypical courses. Localised musculoskeletal infections caused by Nocardia are mostly treated with a combined surgical and antibiotic approach. Antibiotics are typically administered for one to six months. In cases of surgical removal, a shorter antibiotic treatment duration seems sufficient. A multidisciplinary approach involving infectious diseases specialists, microbiologists, and surgeons is critical for achieving favourable outcomes.