Selecting a Treatment Regimen Vancomycin Monitoring
ÎTrough vancomycin concentrations are the most accurate and practical method to guide vancomycin dosing (B-II). Serum trough concentrations should be obtained at steady state conditions, prior to the fourth or fifth dose. Monitoring of peak vancomycin concentrations is not recommended (B-II).
ÎFor serious infections such as bacteremia, infective endocarditis, osteomyelitis, meningitis, pneumonia, and severe SSTI (eg, necrotizing fasciitis) due to MRSA, vancomycin trough concentrations of 15 to 20 mcg/mL are recommended (B-II).
ÎFor most patients with SSTI who have normal renal function and are not obese, traditional doses of 1 gram every 12 hours are adequate and trough monitoring is not required (B-II).
ÎTrough vancomycin monitoring is recommended for serious infections and patients who are morbidly obese, have renal dysfunction including those on dialysis, or have fluctuating volumes of distribution (A-II).
ÎContinuous infusion vancomycin regimens are not recommended (A-II).
ÎThe efficacy and safety of targeting trough concentrations of 15-20 mcg/mL in children requires further study but should be considered in those with serious infections such as bacteremia, infective endocarditis, osteomyelitis, meningitis, pneumonia, and severe SSTI (ie, necrotizing fasciitis) (B-III).
Vancomycin Susceptibility Testing
ÎThere is considerable variability in MIC results depending on the method used. One challenge is that acceptable variability for MIC methods is +/- one doubling dilution making it difficult to distinguish between a MIC of 1 vs. 2 mcg/mL.
ÎEtest, MicroScan, and BD-Phoenix report higher MIC values than reference broth microdilution, overcalling susceptible strains as intermediate in some cases while the Sensititre and Vitek 2 systems tend to undercall resistance.
ÎAs current susceptibility testing methods are unable to reliably distinguish between MICs of 1 mcg/mL from 2 mcg/mL and vice versa, the patient's clinical and microbiologic response should be evaluated along with MIC results when making decisions regarding therapy.
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