Treatment for Septic Knee

Initial Management

The American College of Physicians recommends that septic arthritis of the knee is considered an orthopedic emergency as bacterial proliferation can rapidly cause cartilage damage 1
Obtain appropriate microbiologic cultures (joint fluid, blood) before starting antimicrobial therapy, but do not delay antibiotics more than 45 minutes 1
Administer broad-spectrum IV antibiotics within one hour of diagnosis to cover all likely pathogens, as recommended by the Infectious Diseases Society of America 1, 2

The Infectious Diseases Society of America recommends that drainage or debridement of the joint space should always be performed as the mainstay of therapy 3, 1

Initial empiric antibiotics should include coverage for both gram-positive and gram-negative organisms, as recommended by the American College of Physicians 1
IV vancomycin (15-20 mg/kg/dose every 8-12 hours) is recommended for MRSA coverage by the Infectious Diseases Society of America 3, 1
Consider adding a second agent for gram-negative coverage, such as a third-generation cephalosporin or fluoroquinolone, as recommended by the American College of Physicians 1
Duration of therapy: 3-4 weeks is suggested for uncomplicated septic arthritis by the Infectious Diseases Society of America 3, 1
Longer courses (4-6 weeks) may be needed for patients with slow clinical response or if there is evidence of osteomyelitis, as recommended by the Society of Critical Care Medicine 2

For MRSA infections: IV vancomycin is the first-line treatment, as recommended by the Infectious Diseases Society of America 3, 1
For Pseudomonas aeruginosa bacteremia with septic shock, combination therapy with a beta-lactam and either an aminoglycoside or fluoroquinolone is recommended by the Society of Critical Care Medicine 2, 4
For Streptococcus pneumoniae bacteremia with septic shock, a combination of beta-lactam and macrolide is recommended by the Society of Critical Care Medicine 2, 4

Narrow antibiotic therapy once pathogen identification and sensitivities are established, as recommended by the Society of Critical Care Medicine 2, 5
Empiric combination therapy should not be administered for more than 3-5 days, as recommended by the Society of Critical Care Medicine 2, 4
De-escalation to the most appropriate single therapy should be performed as soon as the susceptibility profile is known, as recommended by the Society of Critical Care Medicine 2

Perform clinical examinations several times per day to assess response to treatment, as recommended by the American College of Physicians 1
Monitor inflammatory markers (ESR, CRP) to guide response to therapy, as recommended by the Infectious Diseases Society of America 3, 1
Consider repeat surgical drainage if there is poor clinical response, as recommended by the American College of Physicians 1
Begin early mobilization when inflammation resolves to prevent joint stiffness, as recommended by the American College of Physicians 1

For prosthetic joint infections, different management strategies may be required, as recommended by the Infectious Diseases Society of America 3

Delayed diagnosis and treatment significantly worsen outcomes - each hour delay in antibiotic administration increases mortality, as recommended by the American College of Physicians 1