FIG 1.

Strain screening method for clinical samples in this study. Strains isolated from oropharyngeal swabs, rectal swabs, nasogastric tubes, nasogastric tubes, tracheal intubation tubes, and tracheotomy tube swabs from the same patient were defined as nonduplicate samples, while strains isolated from the same swab type from the same patient in the same week were defined as duplicate samples. Patients who were already in the intensive care unit (ICU) on the first day of the study without detection of carbapenem-resistant Escherichia coli (CREC) or who were newly admitted to the ICU with negative results of CREC screening within 48 h were defined as patients without CREC.