Health news blog

Septic arthritis is classified as a “rheumatologic emergency” warranting hospital admission and the initiation of parenteral antibiotics to prevent permanent damage to the joint. After obtaining synovial fluid and peripheral blood for cultures, empiric antibiotics should be started. The choice of empiric antibiotic therapy is initially based on Gram stain, age, history of sexual activity, and synovial fluid culture results. Once a specific pathogen is identified, the empiric antibiotic regimen can be suitably narrowed.

For treatment of S. aureus infection, a parenteral beta-lactam, such as nafcillin (typically 2 g intravenously every 4 hours) or cefazolin (500 mg intravenously every 8 hours) is recommended. If the patient is penicillin-allergic or at risk for infection with methicillin-resistant S. aureus, vancomycin should be substituted (1 g intravenously every 12 hours). The recommended total duration of treatment for S. aureus septic arthritis is 3 weeks.

Streptococcal infections should be treated with intravenous penicillin (12 to 18 million units/day administered every 4 hours). Alternative antibiotics include vancomycin and cefazolin. The recommended treatment course for streptococcal septic arthritis is 2 weeks.

For gonococcal septic arthritis, the initial drug of choice is ceftriaxone (1 g intravenously every 24 hours). Response to treatment is typically rapid, and parenteral administration should continue until 48 hours after symptom resolution. Oral medications, including cefixime (400 mg twice daily) or ciprofloxacin (500 mg twice daily), can then be initiated to complete a total course of 7 to 10 days. Doxycycline (100 mg twice daily) should also be given to treat presumed chlamydial co-infection.

For some patients, the initial Gram stain may not be helpful in directing the course of therapy, and broad antimicrobial coverage must be initiated. Treatment for infection with gram-negative rods consists of 3 weeks of a parenteral antibiotic chosen according to culture susceptibility results. In cases in which the initial Gram stain is negative, broad coverage with ceftriaxone for gonococci, streptococci, and staphylococci can be started and altered based on culture results. Patients in whom tissue culture confirms mycobacterial or fungal infection should be referred to an infectious disease specialist for initiation of the appropriate course of therapy.

Repeated needle aspiration of the affected joint may be necessary for any fluid re-accumulation within the first week of treatment. If the patient fails to clinically respond to antimicrobial therapy and repeated aspiration, surgical drainage may be required. Infections of the hip and shoulder typically require open drainage.

*137/348/5*