Evaluation of staphylococcus aureus-related bloodstream infections

Staphylococcus aureus is a leading cause of both community-acquired and nosocomial infections, with particular significance due to its potential to cause bloodstream infections (BSIs) that can result in high mortality. In our study, 321 patients diagnosed with S. aureus BSI between January 1, 2013, and January 1, 2023, were evaluated. Of these patients, 18.1% had BSIs with an unidentified focus, 78.8% had healthcare-associated BSI, and 17.7% were diagnosed with methicillin-resistant S. aureus (MRSA) BSI. It was observed that patients with MRSA-BSI received effective treatment later and had longer hospital stays compared to those with methicillin-susceptible S. aureus (MSSA) BSI. Patients with BSI of unknown focus were found to use immunosuppressive therapy more frequently, undergo fewer invasive procedures, and have shorter treatment durations compared to patients with BSI of identified focus. Our mortality rate was 35.2%. Univariate analysis identified advanced age, ICU admission, hypotension, poor general condition, presence of coinfections, lack of infectious disease consultation, failure to remove infected central venous catheters, MRSA as the causative agent, elevated C-reactive protein and PBS, treatment duration of less than 14 days, and invasive interventions such as mechanical ventilation, central venous catheterization, urinary catheterization, nasogastric intubation, and drainage catheter use as risk factors for mortality. Multivariate analysis revealed ICU admission, hypotension, poor general condition, elevated CRP, and treatment duration shorter than 14 days as independent risk factors. In the treatment of MSSA-BSI, cefazolin was associated with lower mortality rates compared to ampicillin-sulbactam, piperacillin-tazobactam, and vancomycin, although the difference was not statistically significant. Similarly, in MRSA-BSI cases, patients treated with vancomycin exhibited lower mortality rates than those receiving teicoplanin or daptomycin, but this difference also did not reach statistical significance. The relationship between CRP and WBC levels measured at baseline, day 5, and day 10 and mortality was also assessed. The strongest association with 28-day mortality was observed for CRP measured on day 10, with levels above 51.2 mg/L showing 79% sensitivity for predicting mortality. A WBC count exceeding 10,250/µL on day 10 was found to be associated with mortality with 59% sensitivity. Our findings highlight the importance of managing comorbid conditions, establishing appropriate treatment plans, optimizing treatment duration, and consulting with infectious disease specialists in the management of S. aureus BSI.