8. Septic arthritis

Definition
Septic arthritis is an inflammation of a joint caused by bacterial invasion (but not the bacterium that causes gonorrhea).

Alternative Names
Bacterial arthritis; Septic arthritis

Causes, incidence, and risk factors
Septic arthritis develops when bacteria spread from a source of infection through the bloodstream to a joint or the joint is directly infected by traumatic penetration or surgical procedures. The onset of the symptoms is usually rapid with joint swelling, intense joint pain, and low-grade fever.
Risk factors include a simultaneous bacterial infection, chronic illness, diseases or medications that suppress the immune system, rheumatoid arthritis, intravenous drug abuse, sickle cell disease, artificial joint implants, recent joint trauma, or recent joint arthroscopy or other surgery.
Septic arthritis may be seen at any age. In children, it occurs most often in those less than 3 years old. The hip is a frequent site of infection in infants.
Septic arthritis is uncommon from age 3 to adolescence, at which time the incidence increases again (appearing as gonococcal arthritis in females with cervical gonorrhea). Children with septic arthritis are more likely than adults to be infected with group B streptococcus and Haemophilus influenza.
Acute septic arthritis tends to be caused by organisms such as staphylococcus, streptococcus (pneumoniae) and group B streptococcus while chronic septic arthritis (which occurs less frequently) is caused by organisms such as Mycobacterium tuberculosis and Candida albicans. The knee and the hip are the most commonly infected joints.

Symptoms

NEWBORN OR INFANT
• voluntary immobility of the limb with the infected joint (pseudoparalysis)
• cries when infected joint is moved (example: diaper change causes crying if hip infected)
• irritability
• fever

CHILD OR ADULT
• intense joint pain
• joint swelling
• joint, redness
• voluntary immobility of the limb with the infected joint (pseudoparalysis)
• low-grade fever
Uncommon symptoms
• chills

Signs and tests
• synovial fluid analysis or culture of joint fluid
• blood culture
• X-ray of affected joint

Treatment
The goal of treatment is to eliminate the infection with antibiotic therapy.
Antibiotic treatment is initiated as soon as the diagnosis is made, based on the best clinical judgment of the causative organism. Adjustments in antibiotics can be made when culture results showing the causative organism are available. The specific antibiotic used depends upon the sensitivity of the organism to the antibiotics.
When synovial fluid accumulates rapidly in the joint as a result of the infection, frequent aspiration of the fluid by inserting a needle into the joint or surgery may be indicated. Severe cases may require surgery to drain the infected joint fluid.
Rest, immobilization, elevation, and warm compresses may be used at the onset of treatment for pain relief measures. Performing exercises for the affected joint aids the recovery process.

Expectations (prognosis)
Recovery is good with prompt antibiotic treatment. If treatment is delayed, permanent joint damage may result.

Complications
• joint degeneration

Calling your health care provider
Call for an appointment with your health care provider if symptoms of this disorder develop.

Prevention
Prophylactic (preventive) antibiotics may be helpful for high-risk people.

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