Duration of colonization by extended-spectrum β-lactamase-producing Enterobacteriaceae after hospital discharge.

BACKGROUND The duration of gastrointestinal colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) may play a major role in the spread of these organisms. We evaluated the time to, and factors associated with, ESBL-E clearance after hospital discharge. METHODS We retrospectively reviewed prospective surveillance results obtained over 14 years in a 1,000-bed hospital. The surveillance collected demographic, hospital stay, microbiologic, and outcome data. An automatic alert system identified readmitted patients with prior ESBL-E carriage. ESBL-E clearance was defined as a negative rectal screening sample at readmission with no new positive clinical sample during the stay. Variables associated with ESBL-E clearance were identified using a Cox model. RESULTS We included 1,884 patients with 2,734 admissions. Four hundred forty-eight patients with readmission screening formed the basis for the study. Of 448 patients with 1 to 16 readmissions, 180 (40%) were persistent carriers. The median time to ESBL-E clearance was 6.6 months. Variables independently associated with clearance was having the first positive culture in a screening sample only (adjusted hazard ratio, 1.31; 95% confidence interval, 1.02-1.69; P = .04) and period 2005-2010 (hazard ratio, 1.88; 95% confidence interval, 1.33-2.67; P < .01). CONCLUSION We found a long duration of ESBL-E carriage after hospital discharge. An automatic alert system was useful for identifying, screening, and isolating previous ESBL-E carriers.