Relationship between Vancomycin MIC and Failure among Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia Treated with Vancomycin

Abstract

There is growing concern that vancomycin has diminished activity for methicillin-resistant Staphylococcus aureus ( Despite its sustained in vitro microbiologic inhibitory activity, clinicians now question the continued utility of vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) infections (18,23). Within the past 5 years, multiple reports have described MRSA strains with vancomycin MICs at the high end of the CLSI susceptibility range (MICs of 2 mg/liter) (6,18,22). Data suggest that vancomycin has reduced activity against MRSA infections, with vancomycin MICs at the high end of the CLSI susceptibility range (6,11,16,19,20).At the Albany Medical Center Hospital (AMCH), a large proportion of the MRSA bloodstream isolates have vancomycin MICs at the high end of the CLSI susceptibility range. The MIC 50 and MIC 90 for the 76 MRSA bloodstream isolates (59 patients) obtained by using the Etest method and recovered between

The relationship between trough concentration of vancomycin and effect on methicillin-resistant Staphylococcus aureus in critically ill patients

“…9 Others also failed to demonstrate the benefits of recently recommended higher serum vancomycin trough concentrations >15 mg/l in achieving better clinical outcomes. 10,11,17 The current findings may justify the vancomycin trough concentration between 10 and 15 mg/l as an effective and safe target for MRSA infection in critically ill patients. However, this observation has not been interpreted in the presence of MICs, and caution must be exercised before applying this finding to other study populations.…”

“…6 However, a trough concentration >15 mg/l has not been clearly associated with favourable outcomes. 10 An initial response rate of 74% was achieved when target trough concentrations of at least 4 times the MIC were attained. 11 Vancomycin trough concentrations >15 mg/l were also associated with a higher risk of nephrotoxicity.…”

Is vancomycin redundant for serious staphylococcal infection?

“…Other studies [9][10][11][12][13][14][15][16][17] have assessed the efficacy of attaining a target unbound serum trough level of four to five times the MIC. This can be correlated quite well with AUC/MIC ratios and, as we shall see, similar outcome data can be extracted from these studies, adding some weight to the total AUC/MIC ratio of 400 as the correct target.…”

Successful Treatment of Persistent MRSA Bacteremia using High-dose Daptomycin Combined with Rifampicin

“…Recently, the incidence of infections due to MRSA with elevated VCM-MIC has been reported to be increasing in association with treatment failure and poor outcomes (18)(19)(20)(21). Strains with a VCM-MIC of 2-4 μg/mL had previously been categorized as VCM-sensitive strains, but are now considered to have intermediate susceptibility (22).…”