1664 A rare case of Stenotrophomas maltophilia affecting an ACL Endobutton: A Case Report and Review of the literature

Abstract

Abstract Background Stenotrophomas maltophilia (SM) is a ubiquitous opportunistic gram-negative bacillus known to cause hospital acquired infections, commonly in immunosuppressed individuals. However, occurrence of this microorganism is rarely reported in the musculoskeletal system. We report a case of a young healthy man with recurrent knee swelling caused by SM. This organism has been reported to form biofilms over orthopaedic implants, with increased resistance to antibiotic therapy, making it difficult to eradicate once established. Case Report A 34-year-old man with psoriasis and asthma presented with right knee swelling and pain, and no history of preceding trauma or fever. He has a past surgical history of anterior cruciate ligament tear and underwent reconstruction with an endobutton two years prior, and a lateral meniscal repair treated in the previous year. At presentation, he was apyrexial and was noted to have a moderate right knee effusion. Initial radiographic imaging identified a large joint effusion with no obvious evidence of bone destruction, laboratory studies also showed a raised white cell count of 11.4 *10^9/L, C-reactive protein of 54mg/L and aspiration cultures were negative. He subsequently underwent numerous washouts, and removal of endobutton with open synovial biopsy which showed SM. The organism was sensitive to cotrimoxazole. The patient had appropriate antibiotics with resolution of symptoms, however he still presented with recurrence. Conclusions The persistence of SM despite intervention makes it difficult to treat. Although a rare organism, surgeons should consider it as a differential in recurring knee effusion with orthopaedic implants, and institute early and appropriate management for best outcomes.