Infectious arthritis is a type of inflammatory arthritis that affects young and old people alike. It is usually caused by bacteria, fungus, and viruses that enter the joints through the bloodstream, or through contamination during surgery, injection, or injury.

Different bacteria can infect different age groups. For example, staphylococci, hemophilus influenzae, and gram-negative bacilli are most often the cause of the disease in infants. Older children and adults are more likely infected by gonococci (bacteria that cause gonorrhea), staphylococci, and streptococci. Viruses such as HIV (human immunodeficiency virus), parvoviruses, and the bacteria that cause rubella, mumps, and hepatitis B can affect people of any age. Fungal infections and tuberculosis can also lead to chronic joint infections.

If undetected or untreated, infectious arthritis can destroy a joint within days. So, if an infection is suspected, diagnostic tests are run immediately. Typically, these tests involve taking a sample of fluid from within the joint, which is examined in the laboratory for white blood cells and bacteria. Blood tests may also be needed to isolate the bacteria.

Treatment varies, depending on the type of bacteria causing the infection. Antibiotic treatment is started as soon as an infection is suspected. Antifungal medications are used for fungal infections; a tuberculosis infection is treated with a combination of antibiotics. If an artificial joint becomes infected, and a course of antibiotics doesn't clear it up, surgery may be needed to replace the infected joint.

Written and reviewed by the MediResource Clinical Team