Septic Arthritis

What is septic arthritis?
Septic arthritis is simply an infection of a joint.

What causes it?
It’s typically a bacterial infection that is spread through the bloodstream, often from a distant source, such as a skin infection elsewhere on the body or a gastrointestinal infection. It most commonly occurs in joints that have previously been damaged by arthritis (thus offering a nice spot for the bacteria to land). In children, septic arthritis sometimes occurs as an extension of a more local skin infection near the joint.

Is it related to COVID-19 or other contagious diseases?
No.

Is it related to other forms of arthritis?
Only in that it is more common in people who already have other forms of arthritis, such as rheumatoid arthritis (RA) or osteoarthritis (OA), which can cause damage to the joints, setting them up as a site for infection.

Who gets it?
In addition to those who have joint damage from other forms of arthritis, septic arthritis is potentially more common in patients taking medications that suppress the immune system. Patients with joint replacements can get septic arthritis in the artificial joint.

How serious is it?
It can be very serious, because the infection can rapidly damage or even destroy the joint, leading to long-term problems.

How is it treated?
Primarily with antibiotics. Because of the potential damage to the joint, drainage of the infected fluid in the joint, either with a needle or an arthroscope, is an important part of the treatment.

What should people who have other forms of arthritis know about it?
People with other forms of arthritis should be aware of this risk, particularly if they have relatively sudden swelling, redness and pain in a joint that was previously stable, and definitely if they have a fever (as with other infections).

Rheumatologist Eric Ruderman, MD
Professor of Medicine
Northwestern University Feinberg School of Medicine