Risk factors for mortality in patients with persistent methicillin-resistant Staphylococcus aureus bacteraemia in a tertiary care hospital in Taiwan

Abstract

To investigate the determinants of outcome in patients with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia. All patients >or=18 years old with MRSA bacteraemia for >or=7 days from 2000 to 2008 treated at National Taiwan University Hospital were investigated. The associations of mortality with clinical characteristics, management and vancomycin MICs for serial MRSA isolates were analysed. Persistent MRSA bacteraemia occurred in 227 patients. Decreasing trends in the incidence of MRSA bacteraemia (P < 0.001) and persistent MRSA bacteraemia (P = 0.031) were found. Elevated vancomycin MICs for subsequent MRSA isolates were found in 49 (24.6%) of 199 patients, especially those with infective endocarditis (41.9% versus 21.4%; P = 0.027). Metastatic infection [odds ratio (OR) 5.23; 95% confidence interval (CI) 2.17-12.59; P < 0.001], congestive heart failure (OR 4.78; 95% CI 2.19-10.42; P < 0.001) and elevated vancomycin MICs for subsequent MRSA isolates (OR 3.21; 95% CI 1.46-7.07; P = 0.004) were independent predictors of MRSA-related mortality, while metastatic infection (OR 3.01; 95% CI 1.45-6.28, P = 0.003) and congestive heart failure (OR 2.85; 95% CI 1.44-5.56, P = 0.003) were predictors of 30 day mortality. No significant impact of empirical glycopeptide therapy on MRSA-related (P = 0.89) or 30 day mortality (P = 0.26) was found. The 30 day mortality rate was lower in patients who received complete foci eradication (35.6% versus 51.1%; P = 0.03). Congestive heart failure and metastatic infections were predictors of mortality. Isolates with decreased susceptibility to vancomycin that emerged during persistent MRSA bacteraemia were associated with mortality. Aggressive attempts to completely eradicate foci should be encouraged.