Factors
• The most common causative agent is Staphylococcus aureus.
• Neisseria gonorrhoeae is the most common cause in the sexually active young population.
• Gr (-) agents (Escherichia coli and Pseudomonas aeruginosa) may cause septic arthritis in immunocompromised patients or IV drug addicts.
• Staphylococcus epidermidis may be the cause after arthroscopic procedures or prosthetic joint surgery.
• P. aeruginosa is considered in arthritis that develops as a result of a sharp object penetrating the shoe.
• Anaerobic agents can be seen as a result of joint spread of human bite, decubitus ulcer or intra-abdominal infections.
• Polymicrobial infection may develop as a result of complicated traumatic injury.
Spread
• Microorganisms most commonly reach the joint from a distant infection by hematogenous route.
clinical finding
• Acute onset monoarthritis is the most common type of presentation.
• The knee joint is most commonly involved.
• The involved joint is swollen and red. It is extremely painful and sensitive. Movement in the joint is limited.
• Often there is a high fever.
Laboratory findings
• Complete blood count shows leukocytosis, left shift in peripheral smear, and increased acute phase response.
• The number of white blood cells in the joint fluid is more than 50,000/mm3, and more than 80-90% is polymorphonuclear leukocytes.
• Synovial fluid glucose level is low.
Disseminated gonococcal infection
• A special clinical picture develops in some gonococcal infections.
• Migratory polyarthralgia, tenosynovitis and rash (hemorrhagic pustule) are seen in this picture.
• These findings develop as a result of the immune response against circulating gonococci and the accumulation of the formed immune complexes in the tissues.
• Therefore, in these patients, the blood culture may be positive, while the synovial fluid culture is usually negative.
Treatment
• Septic arthritis is a medical emergency. Delay in treatment may cause irreversible joint damage.
• As soon as the diagnosis is made, drainage should be done + culture should be taken + empirical antibiotics should be started immediately.
• Antibiotic treatment and duration are determined according to the culture result;
o The duration of antibiotic treatment should be 1-2 weeks in gonococcal arthritis and 2-4 weeks in staphylococcal arthritis.
o Ceftriaxone is the first choice in gonococcal arthritis. Treatment of staphylococcal arthritis depends on antibiotic susceptibility.