Information on the following diseases can be found in the Related Disorders section of this report:

• Rheumatoid Arthritis
• Reiter's Syndrome
• Psoriatic Arthritis
• Ankylosing Spondylitis (Marie-Struempell disease)
• Osteoarthritis

The symptoms of infectious arthritis depend upon which agent has caused the infection. The symptoms usually include fever (which may be quite high), chills, general weakness and headaches, followed by inflammation of one or more joints. The affected joint or joints often become very painful, swollen, slightly red and stiff within a few hours or days. Rapid onset of symptoms may indicate that a bacterium is the cause. In a few people, however, the infection develops slowly, over a period of months or even years. This slower developing infection is more often the result of a viral or fungal infection than a bacterial one.

Infectious arthritis that affects one joint is often, but not always, bacterial in origin. Occasionally, multiple joints may be involved. Bacterial infections appear to most often affect the larger joints: knees, ankles, shoulders, hips, elbows or wrists. The infection occurs less commonly in other, smaller joints as well. For people who already have some form of arthritis, especially rheumatoid arthritis, the infection may seem like a flare-up of their existing condition.

Symptoms of infectious arthritis caused by a virus vary with the virus involved. Usually, viral arthritic infections develop more gradually and are more widespread than are bacterial infections, affecting several joints. However, some viral infections may develop quickly and affect only a few joints.

In Lyme disease (one form of infectious arthritis), joint inflammation usually occurs several weeks after onset of other symptoms. (For more information on Lyme Disease, choose "Lyme" as your search term in the Rare Disease Database.)

Any disease-causing microbe may infect a joint. Bacteria are most often responsible, typically producing an acute arthritic attack. In young children the most common bacteria are staphylococci, haemophilus influenzae, and gram- negative bacilli. Older children and adults are most commonly infected with gonococci, staphylococci, streptococci or pneumococci. Acute infectious arthritis at any age may be associated with rubella, mumps or hepatitis B infections. Fungi and fungi-like bacteria such as mycobacterium tuberculosis, etc may cause chronic infectious arthritis. People with rheumatoid arthritis and chronically inflamed joints are particularly susceptible to infectious arthritis.

Infectious arthritis can affect people of all ages and both sexes. About half of all cases involve adults over the age of 60. The incidence is reported as 2-10 cases per 100,000 of general population. For patients with immunologic disorders, the incidence increases to about 30-70 cases per 100,000 people. In gonococcal arthritis, the disorder is found in three times as many women as men.

Rheumatoid Arthritis is a chronic disease characterized by usually symmetric inflammation of the peripheral joints, which can eventually result in progressive destruction of joints. Generalized symptoms may also be present.

Reiter's syndrome is arthritis associated with nonbacterial urethritis and conjunctivitis, usually seen in genetically susceptible males following recent sexual exposure. (For more information, choose "Reiter" as your search term in the Rare Disease Database.)

Psoriatic Arthritis is a rheumatoid-like arthritis associated with psoriasis of the skin or nails and a negative RA serology; HLA-B27 antigen is present in most patients. (For more information, choose "Psoriatic Arthritis" as your search term in the Rare Disease Database.)

Ankylosing Spondylitis (Marie-Struempell disease) is a chronic progressive form of arthritis distinguished by inflammation and eventual immobility (ankylosis) of a number of joints, primarily involving the spine and paraspinal structures. (For more information, choose "Spondylitis" as your search term in the Rare Disease Database.)

Osteoarthritis (OA; Degenerative Joint Disease; DJD) is the most common form of arthritis, characterized by degenerative loss of joint cartilage, bony sclerosis beneath the cartilage, and bone proliferation at the joint margins. Secondary synovial tissue inflammation is common.

Diagnosis
A thorough history and physical examination are essential for diagnosis. Blood tests as well as tests of the fluid commonly found in the joints are essential for identification of the infecting agent and to confirm diagnosis. Once the infecting agent is known, an appropriate course of treatment may be designed.

Treatment
Early treatment is required in order to stop the spread of the infection and to avoid destruction of the joint. Successful treatment depends on early and appropriate use of antibiotics. However, examination and culture of the joint fluid should be started before therapy.

The choice of antibiotic depends on the bacterial agent involved. If no organism is present and a gonococcal infection is suspected, penicillin-G is commonly used for treatment. Most clinicians prefer not to inject an antibiotic directly into a joint in order to avoid synovitis. Treatment usually is continued for at least two weeks after all symptoms and signs of inflammation have disappeared.

Fluid from the joint may be cultured to confirm that the infection is gone. If a decrease of symptoms and sterilization of the joint fluid are not apparent after 48 hours of treatment, the choice and dose of the antibiotic may need to be adjusted. Surgical drainage may be indicated when needle aspiration of the joint is difficult, as in hip infections, or if the infection is not controlled after 48 hours. Splinting, in order to rest and to protect the joint, may be useful during the acute stage. Physical therapy is often useful in building up muscle strength preventing stiffness or restoring mobility.

For viral infections, non-steroidal anti-inflammatories may be used to moderate pain and symptoms.

Antibiotic treatment for mycobacterial or fungal arthritis is usually the same as for other serious infections by these agents.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

The use of the anti-inflammatory drug sulfasalazine is being tested for the treatment of seronegative spondyloarthropathies. The drug has been found to be helpful in the treatment of psoriatic arthritis, infectious arthritis, Reiter's syndrome, and ankylosing spondylitis with peripheral joint involvement. More studies are needed to determine the long-term safety and effectiveness of this treatment.

TEXTBOOKS
Goldenberg DL. Bacterial Arthritis. In: Kelley WN, Harris ED, Ruddy S, et al. Textbook of Rheumatology. 4th ed. W. B. Saunders Company. Philadelphia, PA; 1993:1449-63.

Meier JL, Hoffman GS. Mycobacterial and Fungal Infections. In: Kelley WN, Harris ED, Ruddy S, et al. Textbook of Rheumatology. 4th ed. W. B. Saunders Company. Philadelphia, PA; 1993:1467-80.

Steere AC. Lyme Disease. In: Kelley WN, Harris ED, Ruddy S, et al. Textbook of Rheumatology. 4th ed. W. B. Saunders Company. Philadelphia, PA; 1993:1485-90.

Schnitzer TJ. Viral Arthritis. In: Kelley WN, Harris ED, Ruddy S, et al. Textbook of Rheumatology. 4th ed. W. B. Saunders Company. Philadelphia, PA; 1993:1494-1506.

REVIEW ARTICLES
Schett G, Herak P, Graninger W, wt al. Listeria-associated arthritis in a patient undergoing etanercept therapy: case report and review of the literature. J Clin Microbiol. 2005;43:2537-41.

Toivanen A, Toivanen P. Reactive arthritis. Best Pract Res Clin Rheumatol. 2004;18:689-703.

Childs SG. Reactive arthritis. Immune-mediated synovitis or joint infection. Orthop Nurs. 2004;23:267-73.

Andersson U, Tracey KG. HMGB1 as a mediator of necrosis-induced inflammation and a therapeutic target in arthritis. Rheum Dis Clin North Am. 2004;30:627-37.

Robben SG. Ultrasonography of musculoskeletal infections in children. Eur Radiol. 2004;14 Suppl 4:L65-77.

Learch TJ. Imaging of infectious arthritis. Semin Musculoskelet Radiol. 2003;7:137-42.

Nolla JM, Gomez-Vaquero C, Corbella X, et al. Group B streptococcus (Streptococcus agalactiae) pyogenic arthritis in nonpregnant adults. Medicine (Baltimore). 2003;82:119-28.

Garci-De La Torre I. Advances in the management of septic arthritis. Rheum Dis Clin North Am. 2003;29:61-75.

Flores D, Marquez J, Garza M, et al. Reactive arthritis: newer developments.
Rheum Dis Clin North Am. 2003;29:37-59.

Hammerschlag MR. The intracellular life of chlamydiae. Semin Pediatr Infect Dis. 2002;13:239-48.

FROM THE INTERNET
Peng S. Non-gonococcal (septic) bacterial arthritis, MedlinePlus. Update Date: 4/20/2005. 3pp.
www.nlm.nih.gov/medlineplus/ency/article/000430.htm

Infectious Arthritis. The Arthritis Foundation. ©2001. 4pp.
www.arthritis.org/conditions/onlinebrochures/Infectious_Arthritis.pdf

Infectious Arthritis. The Merck manual—Second Home Edition. ©2004. 2pp.
www.merck.com/mmhe/sec05/ch065/ch65c.htm