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Amikacin penetration into synovial fluid during treatment of septic arthritis
Abstract:
The concentration of amikacin from simultaneous synovial fluid and serum samples was measured on four separate occasions in a patient treated for Serratia marcescens septic arthritis. Synovial fluid levels were between 12.5 and 24.4 micrograms/ml, with concurrent serum levels of 12.1-21.0 micrograms/ml. Parenterally administered amikacin readily distributed into synovial fluid. Failure to eradicate the patient's Serratia septic arthritis with amikacin and daily arthrocentesis may have been a result of inactivation of the antibiotic arising from acidosis occurring in the synovial fluid.
Insights
Amikacin effectively penetrates synovial fluid in patients with Serratia septic arthritis. However, localized acidosis may inactivate the antibiotic, hindering treatment success.
Area of Science:
- Pharmacokinetics
- Infectious Diseases
- Rheumatology
Background:
- Septic arthritis requires effective antibiotic penetration into joint fluid.
- Amikacin is a potent aminoglycoside antibiotic used for serious Gram-negative infections.
- Serratia marcescens is a potential pathogen in septic arthritis.
Observation:
- Amikacin concentrations were measured in serum and synovial fluid of a patient with Serratia marcescens septic arthritis.
- Samples were collected on four separate occasions during treatment.
- The patient also underwent daily joint fluid aspiration (arthrocentesis).
Findings:
- Amikacin readily distributed into the synovial fluid, with levels ranging from 12.5 to 24.4 µg/ml.
- Concurrent serum concentrations ranged from 12.1 to 21.0 µg/ml.
- Despite adequate drug levels, the infection was not eradicated.
Implications:
- Parenteral amikacin achieves therapeutic concentrations in synovial fluid.
- Acidosis within the synovial fluid may lead to amikacin inactivation.
- This inactivation could explain treatment failure in severe septic arthritis cases.