Proteus Mirabilis Septic Arthritis in an Elite Athlete with Remote History of ACL Reconstruction

Case: A 21-year-old Division I football player with remote history of anterior cruciate ligament (ACL) reconstruction presented with Proteus mirabilis septic arthritis and underwent emergent arthroscopic irrigation and debridement, followed by targeted antibiotic therapy. Repeat irrigation was required due to persistent purulent drainage. Three months later, he sustained a traumatic ACL graft rupture and underwent revision ACL reconstruction with excellent return to sport. Conclusion: This rare case of P. mirabilis septic arthritis following prior ACL reconstruction in a Division I athlete emphasizes the importance of considering atypical pathogens, even in low-risk individuals. Prompt diagnosis, debridement, and antibiotics are critical, although subsequent ACL graft rupture highlights potential increased reinjury risk.