Infectious Arthritis

This sudden and painful form of arthritis brought on by an infection can quickly and permanently damage joints.

Infectious arthritis, also called septic arthritis, is a painful infection in the joint. It can occur when an infection from another part of your body spreads to a joint or the fluid surrounding the joint. Infection-causing germs may also enter the body during surgery, or through open wounds or an injection. Infectious arthritis usually occurs in only one joint.

Most cases of infectious arthritis are caused by bacteria. The most common of these is Staphylococcus aureus (staph), a bacterium that lives on healthy skin. Infectious arthritis can also be caused by a virus or a fungus. 

In most cases, infectious arthritis develops when an infection somewhere else in the body travels through the bloodstream to the joint. Less commonly, the infection enters the joint directly through a puncture wound or surgery on or near the joint.
Symptoms of septic arthritis usually come on rapidly and include intense swelling, pain, fever and chills. Infectious arthritis typically strikes the knee, but hips, ankles and wrists may also be affected. Rarely, infectious arthritis affects more than one joint. 
Diagnosis of infectious arthritis will include a complete medical history, physical exam and laboratory tests. Analyzing a sample of joint fluid can determine what organism is causing the infection and help the doctor plan treatment. X-rays and other imaging tests may be ordered to assess any damage to the affected joint.
Doctors treat infectious arthritis using a combination of antibiotic drugs and joint drainage.
  • Antibiotics. Treatment will depend on the type of germ causing the infection. Bacterial infections are almost always treated with antibiotics. The type of antibiotic used will depend on the type of bacteria causing the infection. Antibiotics may be taken by mouth or given intravenously. Antibiotics often stop the infection in a few days, but in some cases, they must be given over several months. Infectious arthritis caused by a virus usually goes away on its own with no specific treatment and fungal infections are treated with antifungal medication.
  • Joint Drainage. Many people with infectious arthritis need to have their joint fluid drained. This is done to remove infected synovial fluid, relieve pain, reduce inflammation and prevent further damage to the joint. The least invasive procedure is called joint aspiration, during which a doctor (or another health care provider) inserts a needle into the joint and withdraws fluid. Sometimes a procedure called arthroscopy is used to drain fluid or, in more challenging cases, open joint surgery. 
In addition to treatment prescribed by your doctor, it is important to rest and protect the inflamed joint(s). After the infection is gone, gentle exercise is helpful for building muscle strength to support the joint and to improve range of motion.

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