Summary

Septic arthritis typically presents as a hot, swollen joint. Rapid recognition and treatment of this condition is essential to prevent permanent joint damage. However, septic arthritis does not always present in a textbook manner. The case presented here concerns septic arthritis affecting the right sternoclavicular joint. The patient did not have any risk factors for septic arthritis and presented with a swollen tender joint that was not hot. He was treated with penicillin and then amoxicillin for a total of 12 weeks and made a full recovery. The organism isolated from his right sternoclavicular joint was Neisseria elongata, which is the first ever documented case of this organism causing septic arthritis. This case emphasises that the suspicion of septic arthritis should remain high when unexplained monoarthritis occurs and there should be a low threshold in treating monoarthritis as septic arthritis even in the absence of risk factors.