Infectious arthritis (IA), also known as septic arthritis, is a medical emergency.
Most types are caused by bacteria, especially four strains of gram-positive cocci (Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pheumoniae, and Streptococcus viridans); two strains of gram-negative cocci (Neisseria gonorrhoeae and Hemophilus influenzae); and various gram-negative bacilli (Escherichia coli, Salmonella,and Pseudomonas).
However, IA can also be caused by viruses, including those that cause infectious hepatitis, mumps, German measles, or mononucleosis.
Fungal and parasitic arthritis is less common.
In addition, not only the rubella organism but the rubella vaccine may also produce short-lived arthritis about 20% of the time. Symptoms may persist for two to four weeks after the vaccination or, in rare cases, for months. This form of arthritis is usually curable, provided that it is treated promptly.
Without treatment, however, IA can lead to serious damage to the joints or may spread to other parts of the body, causing ankylosis and even fatal septicemia. However, prompt antibiotic therapy and joint aspiration or drainage cures most patients.
IA occurs when an organism spreads from the primary site of infection through the bloodstream and into adjacent bone or soft tissue. It begins abruptly and is frequently characterized by loss of joint function, fever, inflammation, and occasionally chills.
In about half the cases, the knee is involved, followed by the hip, shoulder, wrist, and ankle. Migratory polyarthritis sometimes precedes localization of the infection.
For instance, if the bacteria invades a hip joint, pain may occur in the groin, upper thigh, or buttock or may be referred to the knee. If the organism enters the joint cavity and causes inflammation of the synovial lining, destruction of the bone and cartilage will eventually occur.
Several factors can predispose a person to IA:
- any concurrent bacterial infection;
- any serious chronic illness such as a malignancy, renal failure, SLE, diabetes, cirrhosis, or those with sickle cell anemia;
- alcoholics and intravenous drug abusers have heightened susceptibility, as do the elderly;
- any autoimmune disease as those with rheumatoid arthritis or AIDS;
- use of immunosuppressive drugs;
- recent articular trauma, joint surgery, intra-articular injections, or local joint abnormalities.