The goal of this observational study is to determine retrospectively whether different patient clinical phenotypes (adults and children) develop Staphylococcus aureus bacteremia.The main questions it aims to answer qre:

1. Evaluate its reproducibility and correlation with mortality
2. Derive and validate a simplified probabilistic model for phenotype assignment
3. External validation of the simplified probabilistic phenotype assignment model found and its association with mortality and development of complicated bacteremia in a prospective cohort
4. Apply microbiological, biochemical and immunological techniques to explain the physiopathological and genetic mechanisms underlying the phenotypes.

FOR STANDARD STUDY:

Inclusion Criteria:

• Adults and children with clinically significant Staphylococcus aureus bacteremia (at least two classic systemic inflammatory response criteria: fever, tachycardia, tachypnea, lowered awareness, low blood pressure, leucocytosis/leucopenia, organ failure)

Exclusion Criteria:

• Patients with non-clinically significant bacteremia.
• Death within 48 hours after detection of bacteremia for the inclusion of retrospective cases, life expectancy less than 48 hours for the inclusion of retrospective cases, life expectancy less than 48 hours for the inclusion of retrospective cases.
• Patients under palliative sedation at the time of bacteremia report.
• Polymicrobial bacteremia.

FOR EXTENDED STUDY:

Inclusion Criteria:

• Adults with clinically significant Staphylococcus aureus bacteremia included in the Standard Study
• Selected at random as one of the model phenotypes until completing recruitment (only HUVM and HUVV)

Exclusion Criteria:

• Patients with non-clinically significant bacteremia.
• Death within 48 hours after detection of bacteremia for the inclusion of retrospective cases, life expectancy less than 48 hours for the inclusion of retrospective cases, life expectancy less than 48 hours for the inclusion of retrospective cases.
• Patients under palliative sedation at the time of bacteremia report.
• Polymicrobial bacteremia.

Adults with clinically significant Staphylococcus aureus bacteremia