Resistance Profile of Staphylococcus Aureus in Invasive Infections in the Post-Pandemic Period

This study aimed to characterize institutional susceptibility patterns and the epidemiology of community-acquired invasive infections in a tertiary hospital in southern Brazil in the post–COVID-19 pandemic period, with special attention to the prevalence and resistance profile of Staphylococcus aureus. This retrospective cohort study, approved by an ethics committee, used anonymized electronic medical records of hospitalized adult patients (2021–2023) with community-acquired invasive infection. Of the 586 records analyzed, 203 were included. The variables collected focused on infection etiology and antibiograms, mainly for S. aureus. Statistical analysis was performed using JAMOVI 2.3.28 Solid, with p<0.05. Staphylococcus aureus was the predominant pathogen, found in 77.83% (158/203) of patients. The main infectious foci for S. aureus were bone (48.10%) and soft tissue (20.88%). The mean age of patients infected by Staphylococcus aureus was 57.76 years. Among comorbidities, the most prevalent was systemic arterial hypertension, present in 44.30% of individuals, followed by type 2 diabetes mellitus in 31.64%. Susceptibility analysis to oxacillin showed that 34.81% (55/158) of the strains were resistant (methicillin-resistant Staphylococcus aureus – MRSA) and 65.18% (103/158) were susceptible (methicillin-susceptible Staphylococcus aureus – MSSA. Mortality in infections caused by MRSA strains was 20.00%, whereas in MSSA infections it was 14.56%. Despite the numerical difference, the outcome did not reach statistical significance (p=0.380). The study confirmed the predominance of S. aureus in community-acquired invasive infections. The prevalence of 34.81% of MRSA strains in the post-pandemic period represents an increase compared to previous data from Latin America (12%–26%), indicating a change in the susceptibility profile. Although the higher mortality observed in MRSA infections (20.00%) compared with MSSA infections (14.56%) was not statistically significant in this study, the findings underscore the ongoing need for local epidemiological surveillance to guide therapy and control antimicrobial resistance.