Infectious Arthritis

Infectious Arthritis


Infectious arthritis is a form of joint inflammation caused by a germ. The germ can be a bacterium, a virus or a fungus. Infection of the joints usually occurs after a previous infection elsewhere in the body.

There is usually only one joint involved, though sometimes two or three joints can become infected. Mostly, infectious arthritis affects the large joints (shoulders, hips, knees), but smaller joints (fingers, ankles) can also be involved.


Any person, at any age, can get infectious arthritis. However, some people are more likely to get infectious arthritis than others. These include those with conditions that make it difficult to fight off infection, such as:

  • diabetes
  • sickle-cell anaemia
  • severe kidney disease
  • AIDS
  • immune deficiency
  • some forms of cancer
  • alcoholism
  • intravenous drug abuse

People with an existing arthritis are also more likely to develop infectious arthritis, because germs tend to infect a joint that is damaged, and therefore weaker than a healthy one. If a person has had surgery to replace a joint with an artificial one, this can also provide a slight chance of infection developing. If it does, it usually occurs a short time after the surgical procedure. However, it is not unheard of for infection to show up in a person years after having joint replacement surgery.

Some of the stronger medications used to treat certain types of inflammatory arthritis also lower the body’s resistance to infection, making it easier for infectious arthritis to take hold.

People who work in jobs where exposure to animals, plants, marine life and soil is common also have a higher chance of contracting infectious arthritis.


The symptoms of infectious arthritis vary according to the type of germ causing it. If the arthritis is caused by a bacterium, inflammation is generally located in only one place or area. The infection is often accompanied by fever and chills and its onset is quite sudden. With infectious arthritis caused by a virus, there is usually no fever, but there is an aching feeling all over the body. Inflammation caused by a fungal infection can be in one area or throughout the body, and it usually occurs very slowly, over weeks or months. You may have a mild fever or no fever at all.


With infectious arthritis a germ has travelled through the body to a joint. The germ may have entered the body through the skin, nose, throat or ears, or through an existing wound.

Usually, there has already been an infection elsewhere in the body. For example, if you develop infectious arthritis from the bacterium pneumococcus, which causes pneumonia, you may have already experienced pneumonia in the lungs. After the initial infection, the germ can travel through the bloodstream to the joints, where it then settles and causes inflammation.

Bacteria cause most cases of infectious arthritis. The types of bacteria that might cause such infection include:

  • gonococcus
  • staphylococcus
  • streptococcus
  • pneumococcus
  • hemophilus
  • spirochetes
  • tuberculosis

Certain viruses can also cause infectious arthritis. They include:

  • infectious hepatitis
  • mumps
  • infectious mononucleosis

Fungi are the least common cause of infectious arthritis. They are usually found in:

  • soil
  • bird droppings
  • certain plants, such as roses

Infectious arthritis is not transmittable from one person to the other, but some germs (such as those causing gonorrhoea and measles) can be spread by person-to-person contact. However, while these diseases can be passed on, this does not automatically mean the development of infectious arthritis is.


Infectious arthritis is usually not a long-term illness. Most of the time it can be cured if it is treated promptly and properly. Without treatment however, the affected joints can become very damaged within 24 hours of the infection starting and the infection can spread to other parts of the body.

Establishing the correct diagnosis is important, so if your doctor thinks you have infectious arthritis, he or she may ask questions about the symptoms, other medical conditions, recent travel, illnesses, and contact with people who may have had infections. He or she may also perform a physical examination, and order x-rays and other tests to find out what germ is causing the infection. This can be done by using a needle to removing a sample of fluid from the joint so it can be examined. If tuberculosis or a fungus is the suspected cause, sometimes a small piece of tissue from the joint may need to be cut away and examined. If a virus is suspected, a blood test may be done because your body develops cells called antibodies to fight off the virus. These antibodies will show up in a blood test.

People with infectious arthritis are often put in the hospital for treatment. Sometimes affected joints must be drained of excess fluid that has built up. This is done by inserting a needle directly into the joint. This procedure is usually painless. Sometimes the same joint may need to be drained several times if fluid build-up recurs. Further treatment varies depending on what type of germ has caused the infection. Your active involvement in developing your treatment plan is essential.

If infection is considered, antibiotics should be withheld until a fluid culture has been taken from the infected joint unless the patient is clinically unstable. If this is not done then it will be impossible to diagnose the organism responsible for the infection.