Infectious Arthritis

What is infectious arthritis?

Anatomy of the hip joint

Infectious arthritis is an infection in the joint (synovial) fluid and joint tissues. The infection usually reaches the joint(s) though the bloodstream, although some joints may become infected due to an injection, surgery, illness (such as pneumonia), or injury. Different bacteria and viruses can infect a joint and usually are associated with a person's age, including the following:

  • Staphylococci (a common bacteria that often causes skin infections), Haemophilus influenzae (a bacteria that can infect the larynx, trachea, and bronchi), and gram-negative bacilli (a group of bacteria, including Escherichia coli, or E. coli) are usually associated with young children and infants.

  • Gonococci (the bacteria that causes gonorrhea), staphylococci, and streptococci (a group of bacteria that can lead to a wide variety of diseases) are usually associated with older children and adults.

  • Viruses, such as the HIV, tend to infect the joints of people of all ages.

What are the symptoms of infectious arthritis?

The most common joints affected by infectious arthritis are the knee, hip, shoulder, elbow, wrist, and finger. Most infections only affect one joint. The following are the most common symptoms of infectious arthritis. However, each individual may experience symptoms differently. Symptoms may include:

  • Fever

  • Joint pain

  • Joint swelling

The symptoms of infectious arthritis may resemble other medical conditions or problems. Always consult your doctor for a diagnosis.

How is infectious arthritis diagnosed?

Prompt diagnosis of infectious arthritis is necessary to prevent permanent damage to the joint. In addition to a complete medical history and physical examination, diagnostic procedures for infectious arthritis may include the following:

  • Removal of joint fluid to examine for white blood cells and bacteria

  • Blood tests to detect bacteria

  • Phlegm, spinal fluid, and urine tests to detect bacteria and find the source of infection

Treatment for infectious arthritis

Specific treatment for infectious arthritis will be determined by your doctor based on:

  • Your age, overall health, and medical history

  • Extent of the condition

  • Your tolerance for specific medications, procedures, and therapies

  • Expectation for the course of the disease

  • Your opinion or preference

Infectious arthritis usually requires immediate treatment with antibiotics, which can often improve symptoms within 48 hours. However, certain infections caused by fungi need treatment with antifungal medications, while viral infections usually have to run their course without treatment. To prevent accumulation of pus from the infection, which can damage the joint, the pus may be drained with a needle, tube, or surgery. Other treatment may include:

  • Medications to reduce pain and fever

  • Physical therapy

  • Splinting the joint to relieve pain