Outcome of methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia: impact of diabetes

The aim of this study was to describe the epidemiology of methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia in a diabetic and a non-diabetic population of the University Hospital of Charleroi and to analyze medical outcomes, including risk of metastatic infection and mortality. Descriptive and multivariable analyses were performed using MedCalc 18.9 (MedCalc Software bvba, Ostend, Belgium). A total of 248 patients with MSSA bacteremia were identified between 1st January 2012 and 28th June 2017 out of which 32.7% were diabetic. Within the diabetic patients, we observed more prolonged hospital duration of stay (p = 0.034), more secondary bacteremia of cutaneous sources (including cellulitis, diabetic foot and ulcer) (p = 0.037), and more metastatic infection (p = 0.002). The overall 30-day mortality was 24.2% with no difference between the two groups. With a logistic regression analysis, it was demonstrated that age ≥ 60 years (odds ratio (OR), 2.20 (95% CI, 1.03-4.67)) and Charlson Comorbidity Index (CCI) ≥ 3 (OR, 2.95 (95% CI, 1.51-5.79)) were the only independent risk factors of mortality, while removal of the primary site of infection was a protective factor (OR, 0.27 (95% CI, 0.12-0.62)). Risk of developing metastatic infection was increased with diabetes (OR, 2.08 (95% CI, 1.12-3.90)), while early empirical antibiotic therapy (OR, 0.38 (95% CI, 0.20-0.71)) decreased this risk. Diabetes was not associated with increased 30-day mortality after MSSA bacteremia. However, diabetes increased significantly the risk of metastatic infection. An aggressive treatment of MSSA bacteremia seems crucial to improve the outcome of diabetic patients.