Which statement best defines septic arthritis?

Which statement best defines septic arthritis?

• A. Inflammation of a joint caused by bacterial infection
• B. Inflammation of a joint due to autoimmune disease
• C. Inflammation of a tendon sheath
• D. Inflammation of bone due to infection

Answer: (A)

Septic arthritis is an infection-driven inflammation of a joint caused by bacteria invading the synovial space. This means the joint itself becomes inflamed because an infection is present inside the joint cavity, rather than due to autoimmune or noninfectious causes. Clinically it often presents as a rapid-onset, hot, painful, swollen joint with limited movement, sometimes with fever. The hallmark is purulent synovial fluid with a high white cell count, usually neutrophils, and a culture or Gram stain that identifies the organism. This clarifies why it’s distinct from autoimmune inflammatory arthritis, where inflammation exists without infection and cultures are typically sterile. It also separates it from tenosynovitis, which is inflammation of the tendon sheath around a tendon, not the joint itself, and from osteomyelitis, which is infection of the bone. Because joint infection can quickly damage cartilage and spread systemically, prompt joint aspiration and antibiotic treatment are essential.

Septic arthritis is an infection-driven inflammation of a joint caused by bacteria invading the synovial space. This means the joint itself becomes inflamed because an infection is present inside the joint cavity, rather than due to autoimmune or noninfectious causes. Clinically it often presents as a rapid-onset, hot, painful, swollen joint with limited movement, sometimes with fever. The hallmark is purulent synovial fluid with a high white cell count, usually neutrophils, and a culture or Gram stain that identifies the organism. This clarifies why it’s distinct from autoimmune inflammatory arthritis, where inflammation exists without infection and cultures are typically sterile. It also separates it from tenosynovitis, which is inflammation of the tendon sheath around a tendon, not the joint itself, and from osteomyelitis, which is infection of the bone. Because joint infection can quickly damage cartilage and spread systemically, prompt joint aspiration and antibiotic treatment are essential.