Inclusion Criteria:  Male or female of legal age Bacteriologically proven native septic arthritis Meets the definition of septic arthritis: Bacteriological documentation of joint puncture fluid-Native articulation Free subject, without guardianship or trusteeship, or subordination Non-opposition of the patient after clear and fair information about the study  Exclusion Criteria:  Presence of material in the affected joint Oligoarticular form Arthritis with Mycobacterium Tuberculosis. Associated endocarditis Patients benefiting from a reinforced protection, namely: minors, pregnant and/or breast-feeding women, persons deprived of liberty by a judicial or administrative decision, adults under legal protection