BACKGROUND
Mycobacterium mucogenicum is a rapidly growing nontuberculous mycobacterium that rarely causes cutaneous disease. Patients receiving tumor necrosis factor–alpha (TNF-α) inhibitors are at increased risk for opportunistic and granulomatous infections, including nontuberculous mycobacteria. To our knowledge, this is the first reported case of a cutaneous infection caused by M. mucogenicum in a patient receiving infliximab for inflammatory bowel disease (IBD).
CASE REPORT
We describe a 57-year-old man with Crohn’s disease on infliximab who presented with dermal abscesses, ulcerations, and lymphangitis. The patient initially received empiric levofloxacin therapy and developed an early Achilles tendon rupture within 4 days, likely related to underlying enthesiopathy and fluoroquinolone exposure. Microbiologic evaluation confirmed M. mucogenicum. He was treated with trimethoprim-sulfamethoxazole and clarithromycin, while infliximab was continued due to active disease. The patient showed clinical improvement with resolution of systemic symptoms and progressive healing of skin lesions. Antimicrobial therapy was continued for 6 months with sustained response.
CONCLUSIONS
This case highlights the importance of early recognition of nontuberculous mycobacterial infections in patients receiving TNF-α inhibitors. Combined therapy with clarithromycin and trimethoprim-sulfamethoxazole was safe and effective despite continued infliximab use. Our case suggests that fluoroquinolones should be used with caution in patients with IBD and suspected enthesiopathy due to the potential risk of tendon rupture.

Keywords: Abscess; Inflammatory Bowel Disease; Opportunistic Infections; Mycobacterium mucogenicum; Fluoroquinolones Adverse Effects; Tendon Rupture