Septic arthritis
Septic arthritis is a serious bacterial infection affecting the joints, characterized by the accumulation of pus that can damage surrounding bone and cartilage. It is considered a medical emergency due to its potential to cause joint dysfunction and lead to life-threatening conditions like septic shock if left untreated. Although it can occur at any age, septic arthritis is most prevalent in children under three, with common infection sites including the hip, shoulders, and knees. The infection often stems from bacteria entering the bloodstream from another infection or through direct contamination due to injury or surgical procedures. Symptoms can vary by age, but typically include intense joint pain, swelling, redness, fever, and immobility of the affected limb.
Diagnosis involves a thorough medical history, physical examination, and various tests, including joint fluid analysis and imaging studies. Treatment typically begins with intravenous antibiotics, with a focus on targeting the specific bacteria involved, followed by additional care such as rest and physical therapy. Preventive measures, like timely treatment of bacterial infections and prophylactic antibiotics for high-risk individuals, can help reduce the risk of developing septic arthritis. Early recognition and management are crucial for a favorable recovery.
Septic arthritis
- ANATOMY OR SYSTEM AFFECTED: Bones, joints, musculoskeletal system
- ALSO KNOWN AS: Bacterial arthritis, infectious arthritis, prosthetic joint infection, pyogenic arthritis
Definition
Septic arthritis is a serious infection of the joints caused by bacteria. This infection causes a joint to be filled with pus cells, which release substances directed against the bacteria. However, this action can damage the bone and surrounding cartilage.
Septic arthritis is a medical emergency. If left untreated, it causes loss of function in the affected joint and can lead to septic shock, a potentially fatal condition. With early treatment, however, recovery is usually good.
Causes
Septic arthritis develops when bacteria spread from the source of infection through the bloodstream to a joint. This condition can result from direct infection through an injection, in a penetration wound, during surgical procedures, or from an injury that directly contaminates the joint.
Septic arthritis can strike at any age but occurs most often in children younger than age three years. In infants, the hip is a frequent site of infection; in toddlers, common sites of infection are the shoulders, knees, and hips. In these young persons, the most common bacterial causes are staphylococci (which causes staph infections), streptococci (which triggers strep throat), and Streptococcus pneumoniae, the bacterium responsible for most identified cases of pneumonia. Kingella kingae, a gram-negative coccobacillus, can also cause septic arthritis, particularly in children under three years old.
Septic arthritis rarely occurs from early childhood through adolescence. After this time, its incidence increases. In adults, it most commonly affects weight-bearing joints such as the knees. Mycobacterium, which causes tuberculosis, and Borrelia, the bacterium that causes Lyme disease, can also lead to septic arthritis.
Risk Factors
The following increase one’s chances of developing septic arthritis: diseases that weaken the immune system, such as human immunodeficiency virus infection, or taking drugs that suppress immunity; a history of joint problems or having other types of arthritis, gout, or lupus; a history of intravenous drug use; chronic illnesses such as anemia, diabetes, sickle cell disease, or kidney failure; joint replacement or organ transplant surgery; and skin conditions such as psoriasis or eczema that could allow for infections to penetrate through the skin.
Symptoms
Symptoms of septic arthritis in newborns or infants include crying when the infected joint is moved (such as during a diaper change), immobility of the limb of the infected joint, irritability, fever, and persistent crying for any reason. The symptoms in children and adults include intense joint pain, swelling and redness, fever, chills, and immobility of the infected joint or its limb.
Screening and Diagnosis
A doctor will ask about symptoms and medical history, perform a physical exam, and may refer the patient to a rheumatologist or orthopedics specialist. Tests may include withdrawing a sample of synovial fluid (the fluid that lubricates the joint) from the affected joint to test it for white blood cells and bacteria, performing a culture of blood and urine to rule out other causes (such as gout), X-rays, ultrasounds, and magnetic resonance imaging (MRI) to assess joint damage, and draining fluid from the infected joint. Severe cases may require surgery.
Treatment and Therapy
Antibiotic therapy, which is started as soon as a diagnosis is made, is sometimes initially given intravenously to ensure the infected joint receives medication to kill the bacteria. The specific medications used depend on the type of bacteria determined to cause the infection. The remaining course of antibiotics may be given orally. Rest, immobilizing the joint, and warm compresses may be used to manage pain. Physical therapy or exercises may also speed recovery.
Prevention and Outcomes
To help reduce the chance of getting septic arthritis, one should get prompt treatment for bacterial infections that could lead to septic arthritis. Persons in a high-risk group may be given antibiotics as a preventive measure.
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