Definition of Septic arthritis:

Septic arthritis is inflammation of a joint due to a bacterial or fungal infection. Septic arthritis that is due to the bacteria that cause gonorrhea has different symptoms.

Causes, incidence, and risk factors:

Septic arthritis develops when bacteria or other tiny disease-causing organisms (microorganisms) spread through the bloodstream to a joint. It may also occur when the joint is directly infected with a microorganism from 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 bacteria 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 conditions increase your risk for septic arthritis:

• Artificial joint implants
• Bacterial infection somewhere else 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 injury
• 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 often the 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 they have not been vaccinated.