Arthritis, Infectious

Infectious arthritis (in-FEK-shus ar-THRY-tis) is a bacterial, fungal, or viral infection of the tissue and fluid within a joint * The infection causes inflammation and can result in pain, swelling, and limited motion of the joint.


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Bacterial arthritis


Rheumatoid arthritis

Septic arthritis

What Is Infectious Arthritis?

Most of the time, bacteria cause infectious arthritis. This form of arthritis is also called septic arthritis, and the infected joint is referred to as a "septic joint." Staphylococcus (stah-fih-lo-KAH-kus) or Streptococcus (strep-tuh-KAH-kus) bacteria are the culprits in most cases of septic arthritis. Arthritis also can occur in Lyme disease, tuberculosis, and many other infections. Bacteria can be introduced directly into the joint by injury or surgery, but more often the bacteria are carried to the joint through the bloodstream from an infection somewhere else in the body. The most common cause of septic arthritis in young adults is Neisseria gonorrhoeae (nye-SEER-e-uh gah-no-REE-eye), the bacterium that causes gonorrhea. These bacteria may spread from infected areas, such as the cervix * and rectum * , and infect joints at the hands, wrists, elbows, and knees. Certain viruses, including those that produce measles, rubella (roo-BEH-luh, a rash-causing viral infection that is also called German measles), and hepatitis B or C, also can cause arthritis. Fungi found in soil, bird droppings, and some plants are uncommon causes of infectious arthritis.

People whose immune systems are weak because they have a disease such as diabetes * , sickle-cell disease * , certain cancers, lupus * , or AIDS are more likely to get infectious arthritis. Alcoholism and intravenous drug use also put people at higher risk. Because a joint that is damaged is more vulnerable to germs, people with existing disease involving the joints (for example, rheumatoid arthritis * ) are more likely to develop infectious arthritis. Anyone who has had joint-replacement surgery is at increased risk for infection of that joint in the future.

How Common Is It?

Some places in the world have more cases of infectious arthritis than others. Rates are highest in Africa, Latin America, and Asia. In the United States, about 20,000 cases of infectious arthritis occur each year. Men, women, and children of all ages can get infectious arthritis, but almost half of patients in whom the illness is diagnosed are 65 years or older.

* joint is the structure where two or more bones come together, allowing flexibility and motion of the skeleton.

* cervix (SIR-viks) is the lower, narrow end of the uterus that opens into the vagina.

* rectum is the final portion of the large intestine, connecting the colon to the anus.

* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.

* sickle-cell disease is a hereditary condition in which the red blood cells, which are usually round, take on an abnormal crescent shape and have a decreased ability to carry oxygen throughout the body.

* lupus (LOO-pus) is a chronic, or long-lasting, disease that causes inflammation of connective tissue, the material that holds together the various structures of the body.

* rheumatoid arthritis (ROO-mah-toyd ar-THRY-tis) is a chronic disease characterized by painful swelling, stiffness, and deformity of the joints.

Is Arthritis Contagious?

Infectious arthritis is not contagious, but certain viruses and the bacterium that causes gonorrhea can be transmitted from one person to another. This does not necessarily mean that someone who gets a particular infection caused by these organisms will also get infectious arthritis.

What Are the Signs and Symptoms of Arthritis?

The symptoms of infectious arthritis vary by type of infection and the particular joint that is affected. With septic arthritis, symptoms usually appear within a few hours or days and include redness, warmth, swelling, pain, and sometimes fever and chills. It is difficult to move the affected joint because of the pain and swelling. Arthritis from a viral infection tends to come on more slowly, often with absence of fever and with less swelling, limitation of movement, and pain at the affected joint. Viruses may infect the joint directly, or sometimes the response of the body's immune system to a virus may cause joint inflammation (called "postinfectious arthritis"). Inflammation stemming from a fungal infection or tuberculosis usually develops very slowly, sometimes over weeks or months. The bacteria that cause Lyme disease can settle in a joint and may lead to recurrent bouts of arthritis. Usually, swelling and limitation of movement of the joint are the main symptoms of this form of arthritis.

How Do Doctors Make the Diagnosis?

A doctor who suspects infectious arthritis based on a patient's symptoms and the findings of a physical examination will want to know the details of the person's medical history. Taking a medical history might include asking questions about whether the patient is sexually active, injects drugs, has been bitten by a tick (which can cause Lyme disease), has had arthritis in the past, or has recently been injured, hospitalized, or exposed to an illness. Laboratory tests can help confirm the diagnosis. A common diagnostic test is aspiration * of some of the synovial fluid * within the affected joint. The doctor inserts a thin, sterile needle through the skin directly into the joint and removes a sample of fluid. The fluid is then examined under a microscope to look for evidence of microorganisms (such as bacteria) and infection-fighting white blood cells. Some of the sample is put in a jelly-like medium containing nutrients that support the growth of bacteria, and this is placed in an incubator for a few days. If bacteria grow, bacterial infectious arthritis is diagnosed. This synovial fluid also can be tested for evidence of viral or fungal infections. In addition, blood tests can help diagnose arthritis caused by a virus or bacterium. If the suspected cause of inflammation is a fungus or tuberculosis, a tissue sample from the infected joint may need to be removed and analyzed. X rays, computerized tomography * , or magnetic resonance imaging * studies can detect excess fluid and sometimes destruction of the tissues within or surrounding an affected joint.

* aspiration (as-puh-RAY-shun) is the sucking of fluid or other material out of the body, such as the removal of a sample of joint fluid through a needle inserted into the joint.

* synovial (sih-NO-vee-ul) fluid is the fluid produced in the synovium, the inner lining of the flexible capsule that encloses the joint space between two bones. This fluid lubricates and nourishes the joint.

* computerized tomography (kom-PYOO-ter-ized toe-MAH-gruh-fee) or CT, also called computerized axial tomography (CAT), is a technique in which a machine takes many X rays of the body to create a three-dimensional picture.

* magnetic resonance imaging (MRI) uses magnetic waves, instead of X rays, to scan the body and produce detailed pictures of the body's structures.

What Is the Treatment for Arthritis?

The type of organism causing arthritis determines which medicines are needed to treat the infection. Antibiotics are prescribed to treat joint infections caused by bacteria, and anti-fungal medications are given for infection due to a fungus. Doctors also may recommend that a person with infectious arthritis keep the affected joint elevated, or raised up, and avoid moving it. Over-the-counter anti-inflammatory medications, such as ibuprofen, can relieve swelling and pain. Sometimes, to help healing and decrease discomfort, some of the excess synovial fluid is removed from a joint. This procedure may have to be repeated several times. In certain cases, a septic joint might be drained by a surgical procedure to help cure the infection.

How Long Does the Infection Last?

Eliminating the infection can take time. Antibiotics may need to be given intravenously for 3 weeks or more. It may take even longer for someone to be able to use an affected joint without pain. In cases of severe infectious arthritis, physical therapy may be recommended after other treatment has been completed, to help patients recover full movement and function of the joint. Infectious arthritis can be cured with prompt and proper treatment. In cases that are severe or where treatment is delayed, the infection may cause permanent damage to the joint and the bone, sometimes resulting in persistent pain and disability.

Can Infectious Arthritis Be Prevented?

Abstinence (not having sex) will prevent arthritis caused by STDs like gonorrhea. For sexually active people, the use of latex condoms can lessen the risk of exposure to bacteria that can cause arthritis. Doctors may recommend that people who have a high risk of the disease, such as those with artificial joints, take antibiotics to prevent an infection in the joint, even when the person has no symptoms of disease.

See also
Hepatitis, Infectious
Immune Deficiencies
Lyme Disease
Measles (Rubeola)
Rubella (German Measles)
Sexually Transmitted Diseases
Staphylococcal Infections
Streptococcal Infections



The Arthritis Society, 393 University Avenue, Suite 1700, Toronto, Ontario, Canada M5G 1E6. The Arthritis Society details types of arthritis on its website and tracks research on causes and treatment of the disease.

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Telephone 888-346-3656

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