Septic Arthritis (Infectious Arthritis)
•Medical Author: William C. Shiel Jr., MD, FACP, FACR
•Medical Editor: Catherine Burt Driver, MD
While joint infection occasionally affects people with no known predisposing risk factors, it more commonly occurs when certain risk situations are present. Risks for the development of septic arthritis include taking medications that suppress the immune system, intravenous drug abuse, past joint disease, injury, or surgery, and underlying medical illnesses including diabetes, alcoholism, sickle cell disease, rheumatic diseases, and immune deficiency disorders. People with any of these conditions who develop symptoms of septic arthritis should promptly seek medical attention.
Septic arthritis can be caused by bacteria, viruses, and fungi. The most common causes of septic arthritis are bacteria, including Staphylococcus aureus and Haemophilus influenzae. In certain "high-risk" individuals, other bacteria may cause septic arthritis, such as E. coli and Pseudomonas spp. in intravenous drug abusers and the elderly, Neisseria gonorrhoeae in sexually active young adults, and Salmonella spp. in young children or in people with sickle cell disease. Other bacteria that can cause septic arthritis include Mycobacteriumtuberculosis and the spirochete bacterium that causes Lyme disease.Viruses that can cause septic arthritis include hepatitis A, B, and C, parvovirus B19, herpes viruses, HIV(AIDS virus), HTLV-1, adenovirus, Coxsackieviruses, mumps, and Ebola. Fungi that can cause septic arthritis include Histoplasma, Coccidioides, and Blastomyces.Septic arthritis is not contagious. However, many of the microbes that cause septic arthritis can be transmitted from an infected person to another, including Neisseria gonorrhoeae,Mycobacterium tuberculosis, and HIV.
Health-care professionals diagnose septic arthritis by identifying infected joint fluid. Joint fluid can easily be removed sterilely in the office, clinic, or hospital with a needle and syringe. The fluid is analyzed in a laboratory to determine if there is an elevated number of white blood cells to suggest inflammation. A culture of the joint fluid can identify the particular microbe and determine its susceptibility to a variety of antibiotics.X-ray studies of the joint can be helpful to detect injury of bone adjacent to the joint. MRI scanning is very sensitive in evaluating joint destruction. Blood tests are frequently used to detect and monitor inflammation. These tests include the white blood cell count, sedimentation rate, and C-reactive protein.
•Symptoms of septic arthritis include
o chills, as well as
o joint pain,
o stiffness, and
•Optimally, antibiotics are given immediately. Often, health-care professionals administer intravenous antibiotics in a hospital setting. The choice of antibiotics can be guided by the results of the culture of joint fluid. Until those results are known, empiric antibiotics are chosen to cover a wider range of possible infectious agents. Sometimes, combinations of antibiotics are given. Antibiotics may be required for four to six weeks.
•Drainage is essential for rapid clearing of the infection. Drainage can be done by regular aspirations with a needle and syringe, often daily early on, or via surgical procedures. Arthroscopy can be used to irrigate the joint and remove infected joint lining tissue. If adequate drainage cannot be accomplished with joint aspirations or arthroscopy, open joint surgery is used to drain the joint. After arthroscopy or open joint surgery,