What is Septic Arthritis / Infectious Arthritis?

Septic Arthritis or Infectious Arthritis is infection of a joint due to bacteria or other organisms.

Septic Arthritis also known as Infectious Arthritis refers to infection of a joint. It may involve one or more joints. It most commonly affects the knee joint, followed by hip, shoulder and elbow. Septic arthritis should be considered as a medical emergency and treated immediately; if left

unattended, the joint may get destroyed soon.

Septic Arthritis | Infectious Arthritis

Causes of Septic Arthritis

Bacteria are the commonest organisms that cause septic arthritis. The bacteria that are commonly implicated in this condition include Staphylococcus aureus, Streptococcus, Hemophilus influenzae, Neisseria gonorrhea, Escherichia coli and Pseudomonas aeruginosa. The organisms reach the joint space through blood from the source of infection, which could be an abscess or an injured tissue. They could also spread locally from an infection in the nearby tissues. Viruses, mycobacteria and fungi can also cause septic arthritis.

Causes of Septic Arthritis: Bacteria

Risk Factors of Septic Arthritis

Patients with reduced immunity are at a risk of suffering from septic arthritis. These include:

  • Patients suffering from HIV, diabetes and rheumatic disease.
Risk Factors of Septic Arthritis: HIV
  • Patients on medications that reduce immunity like steroids, anticancer drugs, azathioprine and cyclosporine.
  • Young children and elderly people.

Other predisposing factors for septic arthritis are:

  • Injury to a joint or a neighboring area.
  • Presence of prosthetic joints.

Symptoms and Signs of Septic Arthritis

The patient presents with the following features:

  • Fever with chills
  • Pain and swelling over the affected joint
Symptoms and Signs of Septic Arthritis: Joint Pain and Swelling
  • On examination, the joint appears warm, red, swollen and stiff. The patient is unable to move the limb at the affected joint.

Diagnosis of Septic Arthritis

Septic arthritis is diagnosed using the following tests:

  • Joint fluid examination: The joint fluid is obtained from the affected joint using a needle and syringe. It is examined under the microscope for the presence of white blood cells, which suggest infection. Culture of the fluid will identify the organism responsible for the infection and help to determine its sensitivity to the antimicrobial drug.
  • X-ray: X-ray of the joint can reveal evidence of bone injury.
  • MRI: MRI can aid in the assessment of joint destruction.
Diagnosis of Septic Arthritis: MRI

Treatment of Septic Arthritis

Treatment of septic arthritis includes the following:

  • Antibiotics or other antimicrobials are used in the treatment of septic arthritis. Treatment is started immediately, using broad-spectrum antimicrobials initially. This type of medication covers a wide range of pathogens. Later, based on culture report, a drug that acts specifically against the causative organism will be given. Treatment is given intravenously for a duration of four to six weeks.
Treatment of Septic Arthritis: Antibiotics
  • For rapid recovery, the joint fluid is drained.
  • The joint can be irrigated and infected tissue removed by arthroscopy. Open surgery may be necessary in some cases.


  1. Horowitz DL, Horowitz S, Barilla LaBarca M. Approach to Septic Arthritis. Am Fam Physician. 2011;84(6):653-660.
  2. Septic Arthritis - (http://arthritis.webmd.com/septic-arthritis-symptoms-diagnosis-and-treatment)
  3. Septic Arthritis (Infectious Arthritis) - (http://www.medicinenet.com/septic_arthritis/article.htm)

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