Clinical features of bacteremia caused by methicillin-resistant Staphylococcus aureus in a tertiary hospital

Methicillin-resistant Staphylococcus aureus (MRSA) has become a leading cause of infections in both the community and in hospitals. MRSA bacteremia is a serious infection with a very high mortality rate. The aim of this study was to assess the clinical features of MRSA bacteremia and to evaluate predictors of mortality in patients with this infection. The medical records of 83 patients with MRSA bacteremia, who had been admitted to Nagasaki University Hospital between January 2003 and December 2007, were retrospectively reviewed. Underlying disease, presumed source, MRSA sensitivity, Staphylococcal cassette chromosome mec (SCCmec) types, virulence genes and prognosis were evaluated. Of the 83 patients (44 men and 39 women; mean age: 63.7 years) with MRSA bacteremia, 30 (36.1%) had malignancy and 25 (30.1%) had been treated with immunosuppressive drugs. Fifteen patients (18.1%) were intravascular catheter related. SCCmec typeII accounted for 80% of SCCmec types of MRSA isolates. The mortality rate was 39.8% (33/83), which is similar to that of previous reports. The ratio of males to females, the mean age or the body temperature did not differ between survivors and nonsurvivors. Independent predictors associated with mortality in the multivariate analyses are pneumonia (P = 0.016), treatment with VCM (P = 0.039), and transplantation (P = 0.021). We suggest that poor prognosis achieved with VCM is in part due to its low blood concentration and poor tissue penetration. VCM should not be selected when presumed source of MRSA bacteremia is pneumonia.