High vancomycin minimum inhibitory concentration is associated with poor outcome in patients with methicillin-susceptible Staphylococcus aureus bacteremia regardless of treatment

Abstract

We retrospectively investigated the impact of high vancomycin minimum inhibitory concentration (MIC > 2 μg/ml) on the outcome of 53 patients with bacteremia caused by methicillin-susceptible Staphylococcus aureus (MSSA). Vancomycin MIC was determined by broth microdilution according to CLSI methods. The primary outcome was 30-day all-cause mortality from the date of the first positive blood culture. The mortality rate was 22.6% (12 of 53 patients). High vancomycin MIC (odds ratio (OR) = 9.3; 95% confidence interval (95% CI) = 1.31-63.20; p = 0.027), Charlson comorbidity index ≥ 3 (OR = 10.3; 95% CI = 1.3-102.04; p = 0.03), advanced age (OR = 35.8; 95% CI = 2.3-659.2; p = 0.01), and severe sepsis (OR = 8.5; 95% CI = 1.2-61.4; p = 0.03) were associated with mortality.

Reduced Vancomycin Susceptibility of Methicillin-Susceptible Staphylococcus aureus Has No Significant Impact on Mortality but Results in an Increase in Complicated Infection

“…First, it occurred at a single institution, potentially limiting the generalizability of our findings (2,(18)(19)(20). Second, the available clinical data did not include granular information on treatment (e.g., duration or therapy adjustments), limiting our ability to control for this important determinant of patient outcomes.…”

“…The RVS phenotype in MSSA infection has recently been studied for its effect on clinical outcome. In particular, it has been linked to increased risk of mortality in some studies, although other analyses have failed to show robust associations with clinical outcome (15,(17)(18)(19)(20)(21)(22)(23).…”

Telavancin In Vitro Activity against a Collection of Methicillin-Resistant Staphylococcus aureus Isolates, Including Resistant Subsets, from the United States

“…However, several studies have reported increased treatment failures against isolates displaying elevated vancomycin MIC results (i.e., 2 g/ml) but still considered susceptible based on current breakpoints (7). Interestingly, recent investigations have identified treatment failures in infections caused by both MRSA and methicillin-susceptible S. aureus (MSSA) isolates exhibiting elevated MIC values for vancomycin, regardless of treatment with vancomycin or another ␤-lactam agent (8)(9)(10). This suggests that increasing vancomycin MICs may reflect a yet-to-be-identified marker of host or organism.…”

“…CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoint criteria were applied for comparator agents (16, 21). MRSA isolates were categorized according to the vancomycin MIC (Յ1 versus 2 to 4 g/ml) and daptomycin MIC (Յ0.5 versus 1 to 2 g/ml) results, and group of isolates with MIC values at the upper end of the MIC distributions were compared with those having lower MIC values (10,22). In addition, S. aureus strains showing a phenotype of resistance to methicillin and at least additional three classes of antimicrobial agents were defined as multidrug resistant (MDR).…”

A murine femoral ostectomy model with hardware exchange to assess antibiotic-impregnated spacers for implant-associated osteomyelitis

“…For the development of the murine model, two groups were investigated: a negative control that received a PMMA spacer alone with no antibiotics and a clinically treated group that received both a gentamicin-laden PMMA spacer and additional daily systemic vancomycin (110 mg/kg subcutaneously twice daily) (Caston et al, 2014). Vancomycin was allometrically scaled to simulate the pharmacokinetic profile used in clinical patients, receiving 1 g of vancomycin every 12 h (Albrecht et al, 1991;Crandon et al, 2010).…”