Genomic analysis of Staphylococcus aureus isolates from bacteremia reveals genetic features associated with the COVID-19 pandemic

Genomic analyses of bacterial isolates are effective to compare the prevalence of antibiotic resistance genes and virulence determinants in different contexts. This study provides a comprehensive genomic description of 339 Staphylococcus aureus strains isolated from patients with bacteremia (2014-2022). Nosocomial acquisition accounted for 56.6% of cases, with vascular catheters being the main infection source (31.8%). Fatality (27.4%), persistent bacteremia (19.5%), and septic emboli (24.2%) were documented. During the COVID-19 pandemic, S. aureus bacteremia episodes increased by 140%. Genetic features in pandemic isolates revealed higher prevalence of methicillin (mecA) and macrolide (msrA and mphC) resistance genes. Additionally, genes encoding clumping factors A and B, involved in fibrinogen binding, were more prevalent. This was linked to extensive macrolide use in COVID-19 accessory therapy and elevated fibrinogen levels in SARS-CoV-2 infection. These findings highlight S. aureus adaptation to COVID-19 selective pressures and the value of whole-genome sequencing in molecular epidemiology studies.