What is septic arthritis?
Septic arthritis, also called infectious arthritis, is usually caused by a bacterial infection but may sometimes be caused by a fungal or viral infection. The infection may spread to the affected joint from elsewhere in the body or may be introduced to the joint during an injury or surgery. The condition is typically acute, quickly causing severe joint pain, inflammation and swelling, redness, and in some cases fever and chills; however, it may also become chronic. Septic arthritis can affect any joint but is most frequently found in the knee, hip, shoulder, wrist, elbow, and finger joints. Usually only one joint will be affected but in some cases there may be more than one. This condition needs to be diagnosed and treated quickly because it can destroy joints in a short period of time.
Septic arthritis occurs most often in people who have had a recent traumatic injury to a joint, have had joint surgery or joint replacement, and/or in people who currently have an infection in their blood (bacteremia or septicemia). Microorganisms can spread from an original site of infection into the blood and then can be carried into the joint space. Additional risk factors for septic arthritis include age (older than 80 years) and having diabetes, a weakened immune system, and/or another condition that affects the joints, such as gout or rheumatoid arthritis.
The acute form of septic arthritis is usually caused by bacteria, such as staphylococcus or streptococcus.
Sometimes the microorganisms that cause Lyme disease, HIV, hepatitis B, mumps, or rubella can move into and infect a joint. Chronic septic arthritis is more rare and tends to be caused by microorganisms such as Mycobacterium tuberculosis and Candida albicans.