An 82-year-old man on long-term prednisolone for COPD is started on ciprofloxacin for a urinary infection. One week later he presents with acute heel pain and swelling. What is the most likely diagnosis and the underlying mechanism?
- A Fluoroquinolone-induced tendinopathy via oxidative damage to tenocyte mitochondria and matrix metalloproteinase activation ✓
- B Gouty tenosynovitis from steroid-induced hyperuricemia
- C Reactive arthritis triggered by uropathogenic E. coli
- D Steroid-induced osteonecrosis of the calcaneus
Correct answer: A. Fluoroquinolone-induced tendinopathy via oxidative damage to tenocyte mitochondria and matrix metalloproteinase activation
Explanation
Fluoroquinolones cause tendinitis and tendon rupture, classically of the Achilles tendon, with elderly age and concurrent corticosteroid use being the strongest risk factors. The proposed mechanism involves fluoroquinolone-mediated mitochondrial oxidative stress in tenocytes and upregulation of matrix metalloproteinases that degrade collagen. Regulatory warnings have led to restriction of fluoroquinolones for uncomplicated infections in high-risk patients. Calcaneal osteonecrosis and reactive arthritis do not follow this temporal pattern after antibiotic initiation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.