Determinants of mortality in oncology patients colonized or infected with Staphylococcus aureus

Oxacillin-resistant Staphylococcus aureus (ORSA) infection is an important cause of hospital morbidity and mortality. The objective of this study was to identify the main factors associated with death in patients colonized or infected with Staphylococcus aureus in a cancer center. A matched-pair case-control study enrolled all patients infected or colonized with ORSA (cases) admitted to the Hospital do Câncer in Rio de Janeiro from 01/01/1992 to 12/31/1994. A control was defined as a patient hospitalized during the same period as the case-patients and colonized or infected with oxacillin-susceptible Staphylococcus aureus (OSSA). The study enrolled 95 cases and 95 controls. Patient distribution was similar for the two groups (p > or = 0.05) with respect to gender, underlying diseases, hospital transfer, prior infection, age, temperature, heart and respiratory rates, neutrophil count, and duration of hospitalization. Univariate analysis of putative risk factors associated with mortality showed the following significant variables: admission to the intensive care unit (ICU), presence of bacteremia, use of central venous catheter (CVC), ORSA colonization or infection, pneumonia, use of urinary catheter, primary lung infection, prior use of antibiotics, mucositis, and absence of cutaneous abscesses. Multivariate analysis showed a strong association between mortality and the following independent variables: admission to ICU (OR [odds ratio]=7.2), presence of Staphylococcus bacteremia (OR=6.8), presence of CVC (OR=5.3), and isolation of ORSA (OR=2.7). The study suggests a higher virulence of ORSA in comparison to OSSA in cancer patients.