Septikarthritis

Septikarthritis, commonly referred to as septic arthritis, is an infection of a synovial joint. It is typically caused by bacteria, though fungi or, rarely, viruses can be involved. In adults, hematogenous spread from another infection is the most common route; in children, direct inoculation or hematogenous spread can also occur. The condition usually presents with acute onset of joint swelling, pain, warmth, and reduced range of motion. The knee is the most frequently affected joint, but any joint can be involved. Fever and malaise may accompany the joint symptoms.

Common pathogens vary by age and risk factors. Staphylococcus aureus is the most frequent cause in adults. In sexually active young adults, Neisseria gonorrhoeae can cause a migratory arthritis. Kingella kingae is an important cause in younger children. Gram-negative bacteria, Streptococcus species, and, in prosthetic joints or healthcare settings, broader organisms may be involved. Risk factors include advanced age, preexisting joint disease or implants, diabetes, immunosuppression, intravenous drug use, recent joint surgery, and bacteremia from other sites.

Diagnosis relies on urgent joint aspiration for synovial fluid analysis and culture, along with blood cultures or imaging as needed. Synovial fluid typically shows marked inflammatory markers with neutrophil predominance and elevated white cell counts. Gram stain and culture guide targeted therapy. Imaging, such as ultrasound, helps identify effusions; X-ray or MRI may assess underlying joint damage.

Treatment requires prompt intravenous antibiotics after aspiration and drainage of the joint, either by repetitive aspiration or surgical lavage. Duration is usually 2–6 weeks, tailored to pathogen and clinical response. Complications include cartilage destruction, joint collapse, osteomyelitis, sepsis, and death if not treated promptly. Prevention focuses on early infection control and management of bacteremia sources.