Data collection and definitions
infection, ESBL-E carriage
INFECTION
We collected data on patient admissions and discharges, surveillance samples, and ESBL-E–positive clinical cultures. Among ESBL-E–positive patients, we collected data on the history of ESBL-E carriage, the day of ESBL-E notification to the ward, and the use of barrier precautions per hospital day.ESBL-E carriers were patients with at least 1 positive ESBL-E screening or clinical culture. We considered a patient as an ESBL-E carrier from the day the first positive culture was obtained until discharge, even if follow-up samples were negative. Acquisition of ESBL-E carriage was defined as recovery of ESBL-E isolates from clinical or surveillance cultures after hospital day 3 following an initial negative culture.ESBL-E days were defined as the days between the collection of the first positive sample until discharge for patients both with and without history of previous ESBL-E carriage.Days without notification were the days between collecting the first positive sample until infection control personnel informed the healthcare workers (HCWs) on the ward of the patient with the positive result. If contact isolation was initiated after the first ESBL-E positive culture was collected, but prior to the day of notification, the patient was considered as a known ESBL-E carrier on the ward from the first day of contact isolation.Isolation days were defined as the days between the first day each ESBL-E patient was labeled under contact isolation according to routine hospital records until discharge. Patients with a known history of ESBL-E carriage were placed in pre-emptive contact isolation upon admission; pre-emptive contact isolation was discontinued when screening results were negative. We considered the days of sample collection and the first day of contact isolation as full ESBL-E and isolation days, respectively.To describe the potential impact of time delay between collecting the samples and subsequent contact isolation before the ESBL-E carriers were discharged from the wards, we divided the ESBL-E carriers into 4 groups:Group 1: ESBL-E carriers known on admission were ESBL-E carriers with a history of ESBL-E carriage prior to admission. For confirmation of ESBL-E carriage, a positive admission sample was required. Contact isolation was initiated from the day of admission.Group 2: Same definition as for group 1, but contact isolation was not initiated during the patient’s stay on the ward.Group 3: ESBL-E carriers without previous carriage, who were first identified through screening or clinical samples on the wards. Contact isolation was initiated during the stay on the ward once the positive result was available.Group 4: Same definition as for group 3, but contact isolation was not initiated during the patient’s stay on the ward.