Impact of adherence to quality indicators and effects of targeted treatment with cefazolin or flucloxacillin on in-hospital mortality in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infections: a retrospective observational study.

PURPOSE: To analyze the associations between adherence to quality indicators (QIs) in the treatment of bloodstream infections caused by methicillin-susceptible Staphylococcus (S.) aureus (MSSA) and in-hospital mortality.

METHODS

A retrospective observational study was conducted in patients admitted between 2019 and 2023 to Hospital St. Georg in Leipzig, Germany, with at least one positive blood culture for S. aureus. Ten QIs were categorized into four groups based on blood culture results, echocardiography, antibiotic treatment, and other parameters such as infectious disease (ID) specialist consultation. Propensity score (PS) matching was used to compare in-hospital mortality between MSSA patients treated with flucloxacillin and those treated with cefazolin. Multivariate Cox regression analysis was performed to determine risk factors associated with in-hospital mortality.

RESULTS

Of the 637 patients with S. aureus bloodstream infections, 495 patients with MSSA infection (77.8%) were included in the study. After the introduction of mandatory ID consultation in 2020, the median QI score increased to 9 out of a maximum of 10 points and was significantly higher in surviving cases than in fatal cases in subsequent years. There was a non-significant decrease in in-hospital mortality from 2019 (28.8%) to 2023 (22.7%) (p = 0.432). Based on PS matching, cefazolin had a favorable hazard ratio of 0.44 (95% CI 0.28-0.71; p < 0.001) for in-hospital mortality. The results of multivariate Cox regression analysis showed a significantly higher survival rate in patients who received QI-based management, including transesophageal echocardiography and antibiotic therapy initiated within 24 h.

CONCLUSIONS

ID consultation is associated with better adherence to quality improvement measures. Targeted MSSA therapy with cefazolin, early initiation of antibiotic therapy, and adherence to antimicrobial treatment protocols increased survival rates in our study setting.