What Is Infectious Arthritis?
Infectious arthritis, which is also called septic arthritis or pyogenicarthritis, is a joint inflammation due to infection by one of a number of microorganisms. The infectious organism may enter the joint directly from a wound, or the infection may spread from a nearby site (such as a boil), but most often it travels to the joint via the bloodstream from an infection elsewhere in the body. The knee and other weight-bearing joints are the ones most commonly affected.
Infectious arthritis is not a permanent condition and does not lead to other forms of joint inflammation, such as osteoarthritis or rheumatoid arthritis. However, if left untreated, it may cause lasting stiffness and limitation of movement in the affected joint or joints.
What Causes Infectious Arthritis?
- A bacterial infection in another part of the body may invade a joint (usually only one) and result in infectious arthritis, typically accompanied by severe joint pain and swelling, fever, and a general feeling of illness. Staphylococcus, the strain of bacteria that causes skin infections (boils), is the most common underlying cause, but various other strains may produce infectious arthritis too, including those that cause strep throat, gonorrhea, and tuberculosis. Most cases of bacterial arthritis tend to be acute but relatively short-lived, except for those associated with tuberculosis, which tend to be milder and progress gradually over a period of months.
- Gonococcal bacterial arthritis affects people who do not have a previously damaged joint or bloodstream infection. The gonococcal organism is the most common cause of infectious arthritis among sexually active young women and men. Newborns are most likely to acquire gonococcal infections from a mother with gonorrhea. It is rare after age 45. Unlike the other types of bacterial arthritis, it may affect several joints at once, especially those in the hands and wrists.
- Lyme disease, which is transmitted by a tick bite, can cause an intense arthritis, usually in a knee or ankle. Often preceding Lyme arthritis is a very red, circular rash. Antibiotics are necessary for the resolution of the arthritis.
- Nongonococcal bacterial arthritis affects patients with specific risk factors—including abnormal joint anatomy (such as in rheumatoid arthritis), previous joint trauma or surgery, advanced age, diabetes, corticosteroid or other immunosuppressive use, and endocarditis (infection of heart valves).
- Viral infections can also cause arthritis. The most common of these is due to parvovirus. Parvovirus arthritis occurs most often in younger women who contract the infection from their children. Other viral infections that can cause arthritis are hepatitis B, rubella, mumps, infectious mononucleosis, and herpes. Viral arthritis often affects multiple joints but generally leaves no permanent damage.
- Fungal infection may cause infectious arthritis; it typically progresses more slowly and is milder than bacterial arthritis.
Symptoms of Infectious Arthritis
- A painful, red, warm, swollen, and stiff joint with limited use; in some cases, multiple joints are affected
- Fever (possibly as high as 104°F) and chills
- Skin rash (with Lyme arthritis, as well as gonorrheal, syphilitic, and some varieties of viral arthritis)
- Nausea and vomiting, sore throat and/or headache
Infectious Arthritis Prevention
- Obtain prompt treatment for infections elsewhere in the body.
Diagnosis of Infectious Arthritis
- Patient history and physical examination
- Fluid culture from the swollen joint. Fluid may be withdrawn with a needle and syringe (arthrocentesis). Surgery (arthrotomy) may be required to obtain fluid from some joints (such as the hip) and to treat prosthetic joint infections.
- Blood culture
- X-rays, CT (computed tomography) scans, or MRI (magnetic resonance imaging)
- Phlegm, spinal fluid, and urine tests are performed to find the source of infection.
Infectious Arthritis Treatment
- Antibiotics are prescribed to treat bacterial infections and Lyme arthritis. These drugs should be taken for the full term prescribed—which may be as long as six weeks or more in severe cases—even if symptoms subside before that time. Failure to do so can permit the strongest, most virulent strains of the underlying organism to survive and multiply, which may result in an even more severe rebound infection that is harder to treat. For acute bacterial infections, antibiotics are often initially delivered in very high doses by intravenous injection.
- Aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) may be administered to reduce pain and inflammation in viral infections.
- More potent painkillers, such as narcotics, may be prescribed in severe cases.
- Amphotericin B, an antifungal drug, may be used for fungal infections.
- Surgery (arthrotomy) is often performed to drain the fluid from the infected joint. Repeat needle aspirations may also be performed at the bedside.
- Infection in a prosthetic joint usually requires removal of the prosthesis. A new joint can be implanted after intensive treatment cures the infection.
- Physical therapy is usually needed after the infection has subsided to regain mobility and strength in the affected joint.
When to Call a Doctor
- Call a doctor immediately if you develop symptoms of infectious arthritis. Prompt treatment may help prevent permanent damage to the joint.
- Consult your doctor immediately if you have rheumatoid arthritis or gout and you develop arthritic symptoms that do not respond to the medication prescribed for flare-ups.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media