Vázquez Sánchez, Daniel AntonioGrillo, SaraCarrera Salinas, AnnaGonzález Díaz, AidaCuervo Requena, GuillermoGrau, InmaculadaCamoez, MarianaMartí Martí, SaraBerbel, DàmarisTubau, FeArdanuy Tisaire, María CarmenPujol, MiquelCàmara, JordiDomínguez Luzón, Ma. Ángeles (María Ángeles)2023-01-182023-01-182022-12-032076-2607https://hdl.handle.net/2445/192290Methicillin-resistant Staphylococcus aureus bloodstream infections (MRSA-BSI) are a significant cause of mortality. We analysed the evolution of the molecular and clinical epidemiology of MRSA-BSI (n = 784) in adult patients (Barcelona, 1990-2019). Isolates were tested for antimicrobial susceptibility and genotyped (PFGE), and a selection was sequenced (WGS) to characterise the pangenome and mechanisms underlying antimicrobial resistance. Increases in patient age (60 to 71 years), comorbidities (Charlson's index > 2, 10% to 94%), community-onset healthcare-associated acquisition (9% to 60%), and 30-day mortality (28% to 36%) were observed during the 1990-1995 and 2014-2019 periods. The proportion of catheter-related BSIs fell from 57% to 20%. Current MRSA-BSIs are caused by CC5-IV and an upward trend of CC8-IV and CC22-IV clones. CC5 and CC8 had the lowest core genome proportions. Antimicrobial resistance rates fell, and only ciprofloxacin, tobramycin, and erythromycin remained high (>50%) due to GyrA/GrlA changes, the presence of aminoglycoside-modifying enzymes (AAC(6 ')-Ie-APH(2 '')-Ia and ANT(4 ')-Ia), and mph(C)/msr(A) or erm (C) genes. Two CC22-IV strains showed daptomycin resistance (MprF substitutions). MRSA-BSI has become healthcare-associated, affecting elderly patients with comorbidities and causing high mortality rates. Clonal replacement with CC5-IV and CC8-IV clones resulted in lower antimicrobial resistance rates. The increased frequency of the successful CC22-IV, associated with daptomycin resistance, should be monitored.14 p.application/pdfengcc by (c) Vázquez Sánchez, Daniel Antonio et al., 2022http://creativecommons.org/licenses/by/3.0/es/Staphylococcus aureusEpidemiologia molecularAgents antiinfecciososResistència als medicamentsStaphylococcus aureusMolecular epidemiologyAnti-infective agentsDrug resistanceinfo:eu-repo/semantics/article2023-01-16info:eu-repo/semantics/openAccess36557654