Escherichia coli Sternoclavicular Septic Arthritis Secondary to Colon Cancer-associated Bacteremia.

Non-traumatic sternoclavicular arthritis is typically caused by either degeneration or non-infectious inflammatory conditions, although septic arthritis can often occur due to Staphylococcus aureus, particularly in immunocompromised individuals. We herein present a case of Escherichia coli (E. coli)-induced sternoclavicular arthritis in a Japanese woman with no underlying disease. As no common source of E. coli bacteremia was identified, colonoscopy revealed early-stage rectal cancer. To our knowledge, this is the first report of septic sternoclavicular arthritis in which colorectal cancer was identified as the source of infection. Clinicians should consider colorectal cancer when septic arthritis caused by gut bacteria is diagnosed without a clear source.