Septic arthritis is an acute onset bacterial inflammation, usually involving a single joint
In > 90%), most often in knee joint and wrists.
In IV drug abusers infection of the spine and sacroiliac joints is more common.
The most common organism of non-gonococcal arthritis is staphylococcus aureus.
Other organisms include streptococci, gram-negative bacilli such as E. coli and pseudomonas.
Microorganisms reach the joint by hematogenous spread following bacteremia, so it is important to look for evidence of septic skin lesion, abrasions, endocarditis, IV drug abuse or throat or tract infection.
Organisms can directly enter the joint following penetrating wounds, local osteomyelitis or joint injection.
• Sudden onset
A typical presentation is a single painful joint, often the knee.
Other commonly affected joints are the wrist, hip, shoulder and ankle.
The joint is red, warm and swollen, with a demonstrable effusion and marked limitation of movement.
• Fever with chills in 80% of patients.
Blood culture: positive in 50% of cases.
Aspiration of joint: Synovial fluid is purulent with neutrophil dominant, increased WBC
Gram stain of synovial fluid is positive in 75% of cases. Culture/sensitivity of the fluid is also performed.
• FBE shows leukocytosis.
Admit to hospital