Definition of Septic arthritis:

Septic arthritis is an inflammation of a joint caused by a bacteria infection other than gonorrhea.

Causes, incidence, and risk factors:

Septic arthritis develops when bacteria spreads through the bloodstream to a joint. It may also occur when the joint is directly infected with bacteria during injury or surgery.

Acute septic arthritis tends to be caused by organisms such as staphylococcus, streptococcus pneumoniae and group B streptococcus.

Chronic septic arthritis (which occurs less frequently) is caused by organisms such as Mycobacterium tuberculosis and Candida albicans. The knee and the hip are the most commonly infected joints.

The following increase your risk for septic arthritis:

• Artificial joint implants
• Bacterial infection
• Chronic illness or disease
• Intravenous (IV) drug abuse
• Medications that suppress the immune system
• Recent joint trauma
• Recent joint arthroscopy or other surgery
• Rheumatoid arthritis
• Sickle cell disease

Septic arthritis may be seen at any age. In children, it occurs most often in those less than 3 years old. 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 and Haemophilus influenza.