Post-SARS-CoV-2 pandemic changes in the epidemiology and severity of MRSA-related infective endocarditis

Abstract Background Following the SARS-CoV-19 pandemic the relaxation of non-pharmaceutical interventions (NPIs) and social restrictions has been associated with a resurgence of respiratory viruses, particularly respiratory syncytial virus (RSV) and other respiratory pathogens. Furthermore, a notable increase in antibiotic-resistant bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA), was observed. To date, no studies have evaluated the impact of NPIs' relaxation on the epidemiology and severity of infective endocarditis (IE). Purpose This study aims to evaluate and quantify the effect of the CoV-19 pandemic on trends in hospitalizations, mortality, and clinical severity of IE among inpatients before, during, and after the pandemic. Methods A retrospective population study was conducted from January 1, 2017, to January 1, 2025, involving consecutive patients diagnosed with infective endocarditis at a referral hospital in Tuscany, Italy. The patients were stratified into three groups: pre-pandemic (2017–2019), pandemic (2020–2021), and post-pandemic (2022–2025). Results "During the study period, 597 patients were referred to our center for suspected IE. Of these, a total of 186 (31%) cases of definite IE were diagnosed, temporally divided as follows: 86 pre-pandemics, 35 during the pandemic, and 66 post-pandemics. The incidence of MRSA-related IE admissions increased significantly (23.20% pre-pandemic vs. 29.40% during the pandemic vs. 43.9% post-pandemic, p=0.022) (Figure 1, panel A). The Sequential Organ Failure Assessment (SOFA) score was significantly higher during (p=0.001) and after the pandemic (5.82±4.85 and 4.97±3.64) compared to the pre-pandemic period (3.38±3.75) (Figure 1, Panel B). Sepsis shock was more frequent (26.3% pre-pandemic vs 55.9% during the pandemic vs 53.3% post-pandemic, p=0.044), while abscess rates were similar (20.0% vs. 17.6% vs. 15.1%, p=0.742). Statistically non-significant trends were observed in the rate of acute heart failure that was higher in post-pandemic periods vs pre-pandemic (27.2% vs 19.8%, p=0.183) and in the incidence of septic embolisms (27.5% pre-pandemic vs 37.1% pandemic vs 43.9% post- pandemic, p=0.090). "Mortality rates were notably elevated during the pandemic and remained higher in the post-pandemic period (29.40% and 33.80%, respectively) compared to the pre-pandemic period (18.60%; p=0.018) (Figure 2). The increased incidence of systemic sepsis was identified as a strong independent predictor of in-hospital mortality. Conclusions In-hospital mortality from infective endocarditis has remained elevated post pandemic, largely due to the increased systemic severity linked to a rise in MRSA infections. This trend may be a consequence of the surge in antibiotic resistance during the CoV-19 pandemic, compounded by the rapid easing of restrictions and a potential decrease in natural immunity following extended non-pharmaceutical interventions (NPIs).Temporal trends of MRSIEs and SOFA score Kaplan Mayer curves of mortality