Predicting Risk for Death from MRSA Bacteremia1

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) in the bloodstream is often fatal. Vancomycin is the most frequently prescribed drug for treatment of MRSA infections with demonstrated efficacy. Recently, however, some MRSA infections have not been responding to vancomycin, even those caused by strains considered susceptible. To provide optimal treatment and avoid vancomycin resistance, therapy should be tailored, especially for patients at highest risk for death. But who are these patients? A study that looked back at medical records and 699 frozen isolates found that risk for death from MRSA infection was highest among certain populations, including the elderly, nursing home residents, patients with severe sepsis, and patients with liver or kidney disease. Risk for death was not affected by the type of MRSA strain (vancomycin susceptible, heteroresistant, or intermediate resistant). Risk was lower among those who had consulted an infectious disease specialist. Thus, when choosing treatment for patients with MRSA infection, it is crucial to look at patient risk factors, not just MRSA strain type. For those at high risk, consultation with an infectious disease specialist is recommended.

Risk factors for mortality among patients with Staphylococcus aureus bacteremia: a single-centre retrospective cohort study

“…Our observation that methicillin resistance is not an independent predictor of all-cause mortality corroborates the findings of a comparable American study by Pastagia and colleagues, 25 although several older studies 14,39 reported a significant association. These contradictory results suggest that genetic variations between MRSA strains in different geographic regions may affect disease severity and alter outcomes.…”

“…Additionally, methicillin resistance, hepatic failure, cerebrovascular disease, chronic obstructive pulmonary disease and metastatic cancer were key predictors of mortality in the 90-day postdischarge period. Factors that were previously shown to be predictive of inhospital mortality correlated with the variables identified in our study, including age, 25 sepsis, 25,26 admission to the ICU, 27 hepatic failure, 25 COPD and metastatic cancer. 28,29 The large sample size allowed us to investigate the association between specific patient characteristics and outcomes, rather than aggregating comorbidities using scales such as the Charlson Comorbidity Index.…”

β-Lactams Enhance Vancomycin Activity against Methicillin-Resistant Staphylococcus aureus Bacteremia Compared to Vancomycin Alone

“…The lower attributable mortality rate in our study likely resulted from several factors, including the high proportion of patients receiving early and appropriate therapy, the low VAN MICs of the organisms, efforts to eliminate removable sources of infection, and having a high rate of consultation with an infectious diseases physician. Consultation with an infectious diseases physician has been associated with a lower risk of death from MRSA bacteremia (39). Moreover, it should be noted that the MRSA-attributable mortality rate was lower in the Combo group than in the VAN-alone group.…”

Staphylococcus aureus Infections: Epidemiology, Pathophysiology, Clinical Manifestations, and Management

“…In several recent studies involving consecutive patients with either SAB (MSSA and MRSA) (12,31,32,(56)(57)(58)(59)(60) or only MRSA bacteremia (61)(62)(63)(64)(65)(66), common primary clinical foci or sources of infection are vascular catheter-related infections, SSTIs, pleuropulmonary infections, osteoarticular infections, and IE (Table 2). These common primary clinical foci represent a subset of the common general clinical manifestations of S. aureus infections.…”