Infectious Arthritis

Infectious arthritis, also called septic arthritis, is a type of arthritis caused by an infection in the joint. This occurs when germs, usually bacterial in origin, travel to the joint space from the blood stream or a penetration or puncture wound on the skin.

Causes and Risk Factors

Most types of infectious arthritis are caused by bacteria either from the skin or blood stream. Viral and fungal infections can also cause inflammation of the joint. A common cause of bacterial arthritis is Staphylococcus which lives on our skin. Sometimes a replaced joint can become infected as well.

There are predisposing factors to developing an infection, including:

  • Existing joint damage
  • A weakened immune system, either from medications or underlying illness
  • A thin and fragile skin barrier
  • Recent trauma to a joint


The most common symptoms from an infected joint are:

  • Painful swelling
  • Redness
  • Warmth with or without a fever

Commonly infected joints are the knee, hip, ankle and wrist, but other joints can be infected as well. You may have trouble moving a joint if it is infected.


Typically, your doctor will withdraw fluid from the joint and send it to the laboratory for culture in order to make a diagnosis. If present, the specific bacteria or other infectious agent can be identified for treatment. Blood tests, X-rays, or other imaging may also be used to diagnose an infected joint. Your doctor will assess which of these tests are needed to help determine the kind of infection you have.


The treatment for an infectious arthritis depends on the type of infection. For example, a bacterial or fungal arthritis is treated with antibiotics, while a viral arthritis will typically resolve on its own. The length of time spent on antibiotics will also vary based on diagnosis and can range from a few weeks for a bacterial infection to several months for a fungal infection. Other treatments may include:

  • Draining of the joint to help the infection recede
  • Arthroscopy
  • Medicines for pain and fever
  • Physical therapy to retain muscle strength
  • A splint on the joint to relieve pain

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To learn more about our services or to make an appointment with a Brigham and Women’s Hospital rheumatologist, contact one of our trained coordinators at 1-800-294-9999 to get connected with the best doctor for your needs.

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