Infectious arthritis.

Infectious arthritis should be suspected in any patient with a swollen joint but especially in children, debilitated patients, immunocompromised persons, those with infection elsewhere (even if on antibiotics), and those with other types of arthritis or a prosthetic joint. Diagnosis depends on obtaining joint fluid for culture and Gram stain. Initial appropriate broad spectrum antibiotics are best narrowed to suit the individual organism, which 2 to 6 weeks of therapy can eradicate. Repeated needle aspiration or surgical drainage is usually helpful in lessening joint damage and achieving a more rapid resolution of symptoms.