Analysis of Clinical Subphenotypes in Methicillin-Resistant Staphylococcus aureus Bacteremia: A Post Hoc Analysis of the MRSA-GEIRAS-SEIMC Study

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Background We aimed to identify and evaluate clinical subphenotypes in a cohort of patients with methicillin-resistant Staphylococcus aureus bacteremia (MRSAB) and to assess their association with all-cause 90-day mortality. Methods This post hoc analysis of the MRSA-GEIRAS-SEIMC study was conducted across 15 Spanish hospitals. MRSAB in adult patients from 2019 to 2022 were included. Clinical subphenotypes were identified using a combination of principal component analysis and latent class analysis based on age, sex, comorbidities, SOFA score, creatinine levels, metastatic foci, source, and acquisition. The 90-day mortality associated with each subphenotype was estimated using the Kaplan–Meier method. Cox regression was performed to assess the risk of death. Results A total of 419 MRSAB were included. Four distinct subphenotypes were identified: S1 was associated with younger age, community acquisition, and unknown or skin and soft-tissue infection source; S2 was associated with older age, female sex, high burden of comorbidities, and healthcare-related acquisition; S3 was linked to a catheter source and nosocomial acquisition; and S4 was predominantly associated with the presence of heart valve prostheses, and metastatic foci. Significant differences in all-cause 90-day mortality were observed across subphenotypes: 20.0% in S1, 47.4% in S2, 26.2% in S3, and 35.1% in S4 (P < .01). Cox regression indicated an increased 90-day mortality risk in S2 (HR, 2.98; 95% CI, 1.59–5.56) and S4 (HR, 1.99; 95% CI, 1.16–3.42) compared with S1. Conclusions We identified 4 distinct clinical subphenotypes of MRSAB associated with prognostic outcomes. Further investigation is needed to implement them into clinical practice.