Septic arthritis is inflammation of a joint due to a bacterial infection other than gonorrhea (joint infection due to gonorrhea has different symptoms).

Causes

Septic arthritis develops when bacteria spread through the bloodstream to a joint. It may also occur when the joint is directly infected with bacteria by an injury or during surgery. The most common sites for this type of infection are the knee and hip.

Most cases of acute septic arthritis are caused by organisms such as staphylococcus or streptococcus.

Chronic septic arthritis (which is less common) is caused by organisms such as Mycobacterium tuberculosis and Candida albicans.

The following increase your risk for septic arthritis:

• Artificial joint implants
• Bacterial infection elsewhere in your body
• Chronic illness or disease (such as diabetes, rheumatoid arthritis, and sickle cell disease)
• Intravenous (IV) or injection drug use
• Medications that suppress your immune system
• Recent joint trauma
• Recent joint arthroscopy or other surgery

Septic arthritis may be seen at any age. In children, it occurs most often in those younger than 3 years. The hip is a frequent site of infection in infants.

Septic arthritis is uncommon from age 3 to adolescence. Children with septic arthritis are more likely than adults to be infected with group B streptococcus or Haemophilus influenza., if not immunized.

Symptoms

Symptoms usually come on quickly, with joint swelling, intense joint pain, and low-grade fever.

Symptoms in newborns or infants:

• Cries when infected joint is moved (example: diaper change causes crying if hip joint is infected)
• Irritability
• Fever
• Unable to move the limb with the infected joint (pseudoparalysis)

Symptoms in children and adults:

• Inability to move the limb with the infected joint (pseudoparalysis)
• Intense joint pain
• Joint swelling
• Joint redness
• Low-grade fever

Chills may occur, but are uncommon.

Exams and Tests

• Blood culture
• Joint fluid analysis and culture
• X-ray of affected joint

Treatment

Antibiotics are used to treat the infection.

Rest, immobilization, elevation, and cool compresses may help relieve pain. Performing exercises for the affected joint helps the recovery process.

If joint (synovial) fluid builds up rapidly in the joint as a result of the infection, frequent aspiration of the fluid by inserting a needle into the joint may be needed. Severe cases may need surgery to drain the infected joint fluid.

Outlook (Prognosis)

Recovery is good with prompt antibiotic treatment. If treatment is delayed, permanent joint damage may result.

Possible Complications

• Joint degeneration (arthritis)

When to Contact a Medical Professional

Call for an appointment with your health care provider if you develop symptoms of septic arthritis.

Prevention

Preventive (prophylactic) antibiotics may be helpful for people at high risk.

Alternative Names

Bacterial arthritis; Non-gonococcal bacterial arthritis