An infection of native joints leads generally to suppurative arthritis, which may be of one joint (monarticular) or several joints (oligoarticular). Bacteria that produce symptoms in multiple joints during bacteraemia, such as Neisseria gonorrhoeae, may also induce inflammation in the neighbouring tendon sheaths. Viral infections frequently involve multiple joints and produce inflammation without suppuration. Chronic granulomatous monarticular arthritis may occur because of infection with either mycobacteria or fungi, which must be differentiated from other causes of chronic monarticular arthritis. A sterile arthritis may occur early in infection (as with hepatitis B), or later (as with a post-infectious arthritis). Any patient presenting with an inflamed joint should have infection as a diagnostic possibility and appropriate cultures must be performed.
