Infectious arthritis is a painful swelling in the joints caused by a bacterial, viral, or fungal infection. Infectious arthritis usually results from infectious organisms in the bloodstream travelling to and infecting a joint. Organisms can also enter the body through open wounds to reach a joint. Fungal infections develop more slowly and are typically less severe than bacterial infections.
Risk factors for infectious arthritis include having underlying health conditions that weaken the immune system, such as cancer, diabetes, and HIV/AIDS, or having joint damage. The elderly and very young are also at increased risk. Symptoms of infectious arthritis include severe pain in the affected joint or joints, fever, chills, impaired mobility, joint swelling, fatigue, and redness or warmth of the joint. Most often, only one joint is affected. The knee is the joint most frequently affected by infectious arthritis.
Infectious arthritis is diagnosed by taking a sample of the joint fluid. This fluid will often have a high white blood cell count, as these are the cells responsible for fighting the infectious agent. Bacteria and other organisms can be grown and identified from this fluid. Treatment of infectious arthritis usually involves a combination of antibiotics, antivirals, or antifungals, and draining of the joint fluid. Infected tissue may also need to be removed in a procedure called an arthroscopy. If you have been diagnosed with infectious arthritis, talk to your doctor about the most current treatment options. Support groups are available for more resources and information.