Chronic infectious arthritis

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Chronic infectious arthritis develops over weeks and is usually caused by mycobacteria, fungi, or bacteria with low pathogenicity.
Chronic infectious arthritis accounts for 5% of infectious arthritis. It can develop in healthy people, but patients at increased risk include those with

Rheumatoid arthritis
HIV infection
Immunosuppression (eg, hematologic or other cancers, immunosuppressive drug use)
Prosthetic joints

Examples of possible causes are Mycobacterium tuberculosis, M. marinum, M. kansasii, Candida species, Coccidioides immitis, Histoplasma capsulatum, Cryptococcus neoformans, Blastomyces dermatitidis, Sporothrix schenckii, Aspergillus fumigatus, Actinomyces israelii, and Brucella species.
The arthritis of Lyme disease is usually acute but may be chronic and recurrent.
Unusual opportunistic organisms are possible in patients with hematologic cancers or HIV infection or who are taking immunosuppressive drugs. A prolonged illness and lack of response to conventional antibiotics suggest a mycobacterial or fungal cause.
In chronic infectious arthritis, the synovial membrane can proliferate and can erode articular cartilage and subchondral bone. Onset is often indolent, with gradual swelling, mild warmth, minimal or no redness of the joint area, and aching pain that may be mild. Usually a single joint is involved.
Patients should have fungal and mycobacterial cultures taken of synovial fluid or synovial tissue, as well as routine studies. Molecular testing techniques may also be useful, especially for detecting mycobacteria.
Plain x-ray findings may differ from those of acute infectious arthritis in that joint space is preserved longer, and marginal erosions and bony sclerosis may occur.
Mycobacterial and fungal joint infections require prolonged treatment. Mycobacterial infections are often treated with multiple antibiotics, guided by sensitivity testing results.