Septic arthritis of the knee due to Pantoea agglomerans: look for the thorn.

We report on a patient with septic arthritis of the knee with Pantoea agglomerans after a penetrating black locust thorn injury. Antibiotics alone or in combination with an arthroscopy may be insufficient for achieving source control. Accurate medical history and open debridement with a search for a thorn fragment are key to successful treatment.