- Independent variables for Study 2: demographics, length of hospital stay, epidemiological variables (travels, previous contact with persons colonised by CRE, previous hospitalization, nursing home or other long term-care facility residency, previous colonisation by CRE), comorbidities, acquisition type, SIRS severity in adults, sepsis in children, Pitt score, SOFA score, APACHE-II score, PIM2, invasive procedures, neutropenia, type of infection, microbiological variables, antibiotics received in the last 3 months.