Septic arthritis (also known as infectious arthritis) happens when an infection spreads to one or more of your joints and causes inflammation. The inflammation is in the surface of the cartilage (a type of connective tissue) that lines your joints and the synovial fluid that lubricates your joints. Bacteria, a virus or fungus may cause the infection, which usually comes from another part of your body and spreads to your joint through your blood. Large joints such as your hip and knee are more commonly affected, but you could get septic arthritis in other joints such as your shoulder and ankle.
In the world of medicine, arthritis covers any type of joint inflammation. There are several different kinds of arthritis, including:
You might think that only older people get arthritis, but anyone at any age can get a type of arthritis. In fact, children more commonly experience septic arthritis than adults.
The joint that is most likely to be affected by septic arthritis depends on different factors. In general, larger joints in the lower half of your body, such as your hips, knees and ankles, are more commonly affected.
If the infection that caused your septic arthritis is not treated, the infection can spread to other parts of your body. This is called sepsis and is life-threatening.
Most cases of septic arthritis only involve one joint. In rare cases, multiple joints can have septic arthritis. Staphylococcal infections are the most common cause of septic arthritis, and most cases only involve one joint. Septic arthritis caused by Neisseria bacteria usually involves multiple joints.
Septic arthritis more commonly affects children, but adults can get it as well. People born male at birth between 2 and 3 years of age are most likely to get septic arthritis.
Septic arthritis is not very common. There are approximately 2 to 6 cases of septic arthritis per 100,000 people per year.
Although it’s rare, septic arthritis is a serious condition. It can cause permanent damage to your affected joint and other complications. It can also cause death if it’s not treated. Be sure to see your healthcare provider or go to the nearest hospital immediately if you experience symptoms.
Symptoms of septic arthritis can include:
Septic arthritis is caused by an infection. It can be from bacteria, fungus, mycobacteria, a virus or other pathogens. In most cases, the infection begins somewhere else on or in your body and then spreads through your blood to your joint. More specifically, the following organisms can cause septic arthritis:
Staphylococcus aureus: This bacteria (also known as staph) is the most common cause of septic arthritis in both children and adults.
Methicillin-resistant Staphylococcus aureus (MRSA): MRSA is a type of staph infection that is resistant to some antibiotics. People who have a higher risk of getting septic arthritis from MRSA include those who use IV drugs, HIV (human immunodeficiency virus infection) or diabetes.
Groups A and B streptococci: Streptococci are a kind of bacteria. Elderly people and people with chronic diseases such as diabetes and cirrhosis are at higher risk of getting septic arthritis from streptococci.
Neisseria gonorrhoeae: This bacterium causes gonorrhea, a sexually transmitted infection (STI). People who have gonorrhea can get gonococcal arthritis, which is a form of septic arthritis.
Neisseria meningitides (meningococcus): This bacterium causes meningitis, which is a condition that involves inflammation (swelling) of the protective membranes covering your brain and spinal cord. While it can happen, getting septic arthritis from Neisseria meningitides is rare.
Staphylococcus aureus, a type of bacteria, is the most common cause of septic arthritis in both children and adults. Approximately 37% to 56% of septic arthritis cases are caused by Staphylococcus aureus.
Septic arthritis is not contagious. However, the bacteria that cause septic arthritis, such as Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA) and Neisseria gonorrhoeae, can spread from person-to-person contact.
After a physical exam of your joint, if your healthcare provider suspects you have septic arthritis, they will most likely withdraw synovial fluid (the fluid that lubricates your joint) from your affected joint with a needle. This is called aspiration. They will then do a laboratory test to look at the synovial fluid. Having bacteria in the synovial fluid of your joint confirms the diagnosis of septic arthritis.
Tests that are used to diagnose septic arthritis include:
The following treatments are used for septic arthritis:
The length of time it takes for septic arthritis to fully heal depends on what caused your infection and your overall health. You may have to take antibiotics for a few weeks. It could take longer for your joint to fully heal if the infection caused damage to your joint and the surrounding soft tissues.
Septic arthritis cannot go away on its own since it’s an infection. Bacterial infections need to be treated with antibiotics. If you’re experiencing signs and symptoms of septic arthritis, contact your healthcare provider right away or go to the nearest hospital. Septic arthritis can lead to serious complications and can be life-threatening if it’s not treated.