Acute infectious arthritis is an uncommon disease that is most commonly caused by Neisseria gonorrhoeae or gram-positive cocci. Gram-negative bacteria are an infrequent and highly virulent cause of septic arthritis and most commonly enter the circulation through the urinary tract, as in this case after ureteroneocystostomy. The resulting arthritis carries a mortality of 25% and a morbidity of 80%. Early recognition and treatment with appropriate antibiotics and mechanical drainage is imperative. Needle drainage of the affected joint has been shown superior to open surgical drainage.