Antibiotics to treat nongonococcal septic arthritis
How long is nongonococcal septic arthritis treated?
Antibiotics should be started after cultures are obtained, with the choice of antibiotics determined by the suspected organism based on initial Gram stain and clinical situation. Normal renal function is assumed for all of the following doses.
- • Gram-positive cocci on Gram stain: vancomycin, dosing based on renal function, but usually 15 mg/kg IV every 12 hours.
- • Gram-positive rod: often C . acnes, start ceftriaxone 2 g IV every 24 hours; if allergic to beta-lactams, could use vancomycin.
- • Gram-negative diplococci: usually Neisseria gonorrhoeae or meningitidis. Treat with a third-generation cephalosporin, such as ceftriaxone (2 g IV daily) or cefotaxime (2 g IV every 8 hours).
- • Gram-negative rod: start a third-generation cephalosporin such as ceftriaxone (2 g IV daily) or cefotaxime (2 g IV every 8 hours). If allergic to cephalosporin, one can use ciprofloxacin (400 mg IV every 12 hours).
- • Negative Gram stain: start vancomycin plus ceftriaxone 2 g IV every 24 hours.
- • Human, dog, or cat bites: start ampicillin-sulbactam.
Once the organism has been identified, the antibiotic regimen can be tailored as follows:
|Antibiotic treatment of nongonococcal septic arthritis|
|Organism||Antibiotic of Choice||Alternatives||Duration/Comments|
|Methicillin-sensitive S. aureus||Cefazolin or Nafcillin or oxacillin||Vancomycin|
Tmp/smx∗ or clindamycin
|Methicillin-resistant S. aureus||Vancomycin||Daptomycin|
Clindamycin or Tmp/smx
|Streptococcus pyogenes or S. pneumoniae||Penicillin, ampicillin, or Cefazolin||Ceftriaxone|
|Penicillin or Ampicillin|
Linezolid or daptomycin
|4–6 weeks, consider addition of an aminoglycoside|
|Hemophilus influenzae||Ampicillin||Third-generation cephalosporin|
|Enterobacteriaceae||Third-generation cephalosporin||Ciprofloxacin||4 weeks|
|Pseudomonas||Cefepime or ceftazidime or Piperacillin/tazobac-tam or Meropenem||Ciprofloxacin||4 weeks, consider addition of an aminoglycoside|
|C. acnes||Penicillin or ceftriaxone||clindamycin, doxycycline, or vancomycin||4–6 weeks|
Intraarticular antibiotics should not be used. The total duration of therapy is variable and depends on the patient’s clinical response and improvement in inflammatory markers. ∗Tmp/smx = Trimethoprim/sulfamethoxazole. Sensitivity testing should be performed to ensure susceptibility to above antibiotics.
Pearl: If the patient was on antibiotics prior to synovial fluid aspiration, then need to consider treating organisms that may have been present but have had their growth inhibited. S. aureus and Pseudomonas if present will almost always grow.