(Bacterial Arthritis; Infectious Arthritis; Pyogenic Arthritis)En Español (Spanish Version)
Septic arthritis is a serious infection of the joints caused by bacteria. This infection causes the joint to be filled with pus cells, which in turn release substances directed against the bacteria. However, this action can damage the bone and surrounding cartilage.
This condition is considered a medical emergency; if left untreated, it causes loss of function in the affected joint and can lead to septic shock , a potentially fatal condition. With early treatment, however, recovery is usually good.
Septic arthritis develops when bacteria spreads from the source of infection through the bloodstream to a joint; it can result from direct infection through an injection, penetration wound, during surgical procedures, or injury that directly contaminates the joint.
It can strike at any age but occurs most often in children younger than age three. In infants, the hip is a frequent site of infection; in toddlers, it’s the shoulders, knees, and hips. In these young patients, the most common bacterial causes are:
- Staphylococci ( “staph” infections)
- Streptococci that trigger “strep” throat
- Streptococcus pneumoniae , the bacterium responsible for most identified cases of pneumonia .
Septic arthritis rarely occurs from early childhood through adolescence. After that, its incidence increases. In adults, it most commonly affects weight-bearing joints such as the knees. Mycobacteria, which causes tuberculosis , and the bacterium that causes Lyme disease , can also result in septic arthritis.
Joint Damage in Knee
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The following factors increase your chances of developing septic arthritis. If you have any of these risk factors, tell your doctor:
- Diseases that weaken the immune system, such as HIV , or taking drugs that suppress immunity.
- A history of joint problems or having other types of arthritis , gout , or lupus .
- A history of intravenous drug use.
- Chronic illnesses such as anemia , diabetes , sickle cell , or kidney failure.
- Having joint replacement or organ transplant surgery.
- Skin conditions such as psoriasis or eczema that could allow for infections to penetrate through the skin.
If you experience any of these symptoms do not assume it is because of septic arthritis. These symptoms may be caused by other, less serious health conditions. If you experience any one of them, see the doctor:
Newborn or infants
- Crying when the infected joint is moved, such as during a diaper change
- Immobility of the limb of the infected joint
- Persistent crying for any reason
Children and adults
- Intense joint pain
- Joint swelling and redness
- Immobility of the infected joint or its limb
Your doctor will ask about your or your child’s symptoms and medical history, and perform a physical exam. Your practitioner may refer you to a rheumatologist or orthopedics specialist. Tests may include the following:
- Withdrawing a sample of synovial fluid (fluid that lubricates the joint) from the affected joint to test it for white blood cells and bacteria
- Performing a culture of blood and urine to rule out other causes (such as gout)
- X-rays to assess joint damage
- Possibly draining fluid from the infected joint; severe cases may require surgery.
Antibiotic therapy is started as soon as a diagnosis is made, sometimes initially given intravenously to ensure the infected joint receives medication to kill the bacteria. The specific medications used depend on the type of bacteria determined to cause infection. The remaining course of antibiotics may be given orally.
Rest, immobilizing the joint, and warm compresses may be used to manage pain. Physical therapy or exercises may also speed recovery.
The Arthritis Foundation
The NIH/National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse
Arthritis Society of Canada
St. Joseph's Hospital, Arthritis Institute
The Milton S. Hershey Medical Center College of Medicine website. Available at: http://www.hmc.psu.edu/healthinfo/s/septicarthritis.htm . Accessed Oct. 29, 2006.
The US Library of Medicine website. Available at: http://www.nlm.nih.gov/medlineplus/arthritis.html . Accessed Oct.29, 2006.
Last reviewed February 2008 by David Horn, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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