Joint infections

Joint Infections are infections in a joint or the surrounding fluid often known as synovial fluid. These joint infections are also referred as infectious arthritis or septic arthritis. When bacteria or virus spreads to the joint or the fluid surrounding the joint, it causes infection. This infection can also begin in another part of the body and spreads through the bloodstream to the joint tissue. The infection causing germs may also enter the body during surgery, or through open wounds, or syringes used for injections.

Joint infections are often noticed in the large joints such as the knee, hip, or shoulder, and these infections are mostly confined to only one joint. Joint infections are more common in children, older adults, and people who use illegal drugs.

Signs and Symptoms

The symptoms of joint infections can vary depending on age and the medications you’re taking. The symptoms include severe pain that worsens with movement, swelling of the joint warmth and redness around the joint, fever, chills, fatigue, weakness, decreased appetite, a rapid heart rate, and irritability.


Infections are caused by organisms which include bacteria, virus, and fungi. Many different bacteria can infect a joint. The types of bacteria causing joint infection are classified depending on the patient’s age:

Infants and young children are most often infected with staphylococci, streptococci, and bacteria known as gram-negative bacilli.

Older children and adults are most often infected with staphylococci, streptococci, and gonococci.

Bacteria such as spirochetes and those that cause Lyme disease, and syphilis can also infect joints.

Viruses such as parvoviruses, HIV and those that cause mumps, rubella, and hepatitis B and hepatitis C, can infect patients with any age.

Risk factors

There are many risk factors for joint infections. Most children who develop joint infections do not have identified risk factors. Open wounds are at a higher risk for joint infections. If you have a weakened immune system or pre-existing conditions such as cancer, diabetes, intravenous drug abuse, and immune deficiency disorders you may be at a higher risk of joint infections. Previously damaged joints have an increased likelihood of becoming infected.


If the condition is left unnoticed or untreated, you are at a risk of complete disabling of the joint.

Prevention or self-management

Joint infections can be prevented by seeking prompt medical assistance if you suspect any infection. This can help reduce your risk of developing pain and inflammation associated with the joint infection. If you are suspected as a risk factor for septic arthritis, consult your doctor and discuss taking preventive antibiotics.

The joint infections are usually diagnosed with the help of laboratory tests. The tests used to diagnose joint infections include:

  • Analysis and culture of joint fluid
  • Blood tests
  • Sputum, spinal fluid, and urine tests
  • Magnetic resonance imaging (MRI) or ultrasonography

You doctor usually suspect and diagnose joint infections if you have severe or unexplained arthritis or joint pain and also have other combinations of symptoms that are common with people who have infectious joints.

A sample of joint fluid is aspirated with the help of a needle, and examined for an increased number of WBCs, and the type of bacteria (culture) and other organisms.

Blood tests are often recommended by your doctor as bacteria causing joint infections often appear in the bloodstream also.

Sputum, spinal fluid, and urine are also tested for bacteria to determine the source of infection and presence of infection in any other part.

If the infected joint is not easily accessible for examination or aspiration, then your doctor may order a magnetic resonance imaging (MRI) or ultrasonography to identify accumulations of fluid or collections of pus.

The objective of joint infections treatment is to relieve the symptoms followed by removing the infection from the body. The treatment procedure is performed in three different steps which include:

  • Usage of antibiotics or antifungal drugs
  • Splinting of the joint and physical therapy
  • Removal of pus

Antibiotics are started as soon as an infection is suspected even before the infected organism is identified by the laboratory reports. The laboratory test to identify the causative organism in the joint fluid takes at least 48 hours. Intravenous antibiotics are also given to ensure the immediate effect of the drug. Antibiotics may be changed after receiving the laboratory reports after 48 hours depending on the sensitivity of the particular bacteria to specific antibiotics.

The puss is removed or drained by placing a needle as the accumulation of pus may damage the joint and may be more difficult to be cured with antibiotics. Sometimes drainage with a needle is difficult in the case of hip joint infection, arthroscopy or surgical procedure may be needed to drain the joint. The procedure for draining may be done more than once and sometimes a drain tube is left in the joint to drain the pus.

Splinting of the joint is done to help ease the pain. Physical therapy is started later to strengthen muscles and prevent stiffness and permanent loss of function of the joint.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are also used as they can help to reduce pain, inflammation, and fever.