Case Report and Literature Review of : Difficult-to-Treat Arthritis in Hiding.

Septic arthritis is a life-threatening rheumatological syndrome that is highly related to a patient's immune status and comorbidities, and although the most common clinical presentation is rapid-onset monoarthritis, it can also appear as subacute or chronic joint swelling. In these cases, differential diagnosis is more challenging, but early diagnosis and treatment is no less urgent to ensure a good global prognosis and the best outcome of the affected joint. Anaerobic microorganisms, such as , are an uncommon cause of septic arthritis (less than 5% of cases) but may be the cause of subacute arthritis.