Association between acessory gene regulator II expression and mortality among critically ill patients receiving vancomycin for hospital-acquired methicillin-resistant Staphylococcus aureus bacteremia
Methods: A retrospective cohort was performed at a 30-bed general intensive care unit (ICU) of a tertiary hospital in southern Brazil. All cases of documented hospital-acquired MRSA bacteremia treated with vancomycin in the ICU setting between May 2009 and November 2011 were evaluated. Cox regression was performed to evaluate whether agr-II expression (determined by PCR) was associated with 30-day mortality. Covariates included age, presence of immunossuppression, APACHE-II score, initial C-reactive protein (CRP) plasma levels, initial serum creatinine levels, vancomycin minimum inhibitory concentration, vancomycin serum levels and time to effective antibiotic administration.
Results: In total, 21 patients were evaluated during the study period. The prevalence of agr-II expression was 38% (8 patients). The median APACHE-II of the study population was 23 (IQR, 19 to 31). The overall cohort mortality was 61% (13 patients). After multivariate analysis, initial plasma CRP (P=0.01), initial serum creatinine (P=0.03) and expression of agr-II (P=0.02) were independently associated with the 30-day mortality. Patients receiving vancomycin therapy for bacteremia due to MRSA with agr-II expression had their hazard of death increased by 6.6 times (95%CI, 1.2-37.0) when compared with those with bacteremia by MRSA without agr-II expression.
Conclusion: Expression of agr-II poses risk for mortality in critically ill patients receiving vancomycin for hospital-acquired MRSA bacteremia. Alternative antimicrobial agents including daptomycin and linezolid for treatment of MRSA bacteremia expressing agr-II should be considered in this setting.
D. Machado, None
A. Cechinel, None
R. Dos Santos, None
L. Goldani, None