John Harrison at first blamed himself, thinking he had not taken proper care of his surgical wound. The truth was much worse: he was one of at least seven joint surgery patients at Methodist who acquired dangerous infections during a two-week period. The outbreak led Methodist to close operating rooms and cancel knee and shoulder surgeries while hospital and Centers for Disease Control and Prevention (CDC) investigators searched for the cause. They found two likely sources in unlikely, yet terrifying, spots—deep inside a arthroscopic shaver and inside an inflow/outflow cannula.