[Evaluation of methicillin-resistant Staphylococcus aureus bacteremia and comparison of prognosis according to vancomycin MIC values: experience of the last ten years].

Hospital acquired methicillin-resistant Staphylococcus aureus (MRSA) infections are important health problems. Mortality and morbidity rates associated with MRSA infections are increasing with mortality rates being higher for MRSA bacteremia than the other clinical presentations of MRSA infections. Initiation of treatment immediately and use of appropriate antibacterial agents may lead to better clinical outcomes in MRSA bacteremia. The aims of this study were to evaluate the treatment and clinical outcomes of patients with MRSA bacteremia in a tertiary care hospital in Ankara, Turkey. Two hundred forty seven MRSA strains isolated from blood cultures at Hacettepe University Faculty of Medicine, Clinical Microbiology Laboratory between January 2000-December 2010, were evaluated retrospectively. Demographic characteristics, duration of bacteremia, types and duration of antibiotic treatment, presence of other pathogens and all other necessary information were collected from patients' registry. One hundred eighty four patients who had clinically significant bacteremia were analyzed. The mean age of the patients was 55 ± 17 years, of them 44.6% were female and 55.4% were male. The median length of hospital stay was 61 days. The median duration for the development of MRSA bacteremia from the time of admission was 23 days. Overall mortality rate was 54.9%, and mortality rate due to MRSA bacteremia was 19%. The rate of treatment success was 81%. There were 3 (1.6%) patients with vancomycin MIC value of 0.5 mg/L, 140 (76.1%) patients with 1 mg/L and 41 (22.3%) patients with 2 mg/L. The median duration from the time of MRSA bacteremia detection to the time of death was shorter in unsuccessfully treated group than successfully treated group (7 days vs. 30 days, p< 0.001). Thirty days mortality rate was higher in unsuccessfully treated group than successfully treated group (94.3% vs. 50.7%, p< 0.001). The median time interval between positive and negative cultures was 9.5 days. Number of patients with MRSA bacteremia had been decreasing for the last five years (36 patients in 2006, 18 in 2007, 16 in 2008, 12 in 2009 and one in 2010). In multivariate logistic regression analysis, it was shown that, intubation (OR: 5.086, 95% CI: 2.094-12.351; p< 0.001) and malignancy (OR: 2.789, 95% CI: 1.185-6.564; p= 0.019) were independent risk factors for mortality. In this study, it was shown that mortality rate was high in MRSA bacteremia and high MIC value was not an independent risk factor for mortality. It was also noted that when there was no clinical response to vancomycin, the therapy should be changed immediately. To decrease MRSA bacteremia rates in the hospital adherence to rules of infection control and prevention proved to be important factors.