Efficacy and acceptability of rectal and perineal sampling for identifying gastrointestinal colonization with extended spectrum β-lactamase Enterobacteriaceae

Objectives: We evaluated 'pre-laboratory' factors associated with the detection of extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) colonization including anatomical site, and staff and patient factors. Methods: All admissions to a large London hospital over 3 months were approached to provide rectal and perineal swabs, which were cultured for ESBL-E using chromogenic media. ESBL-E detection rates for patient-or staff-collected rectal or perineal swabs were compared using McNemar tests. Binary logistic regression was used to explore factors associated with patients declining to provide a rectal swab. The impact of simplifying the verbal study description to patients to improve the participation rate was evaluated. Results: Carriage of ESBL-E was significantly higher in rectal swabs than perineal swabs (7.8% of 4006 versus 3.8% of 4006, p <0.001), whether collected by staff or patients; 31.9% of 869 patients did not provide a rectal swab before the change in study description compared with 7.6% of 3690 patients afterwards (p <0.001). In multivariable analysis, factors associated with patients declining to provide a rectal swab were younger age (OR 0.99, 95% CI 0.99-1.00), female gender (OR 1.26, 95% CI 1.04-1.52), transfers from other hospitals (OR 1.77, 95% CI 1.07-2.93) or an unknown admission route (OR 1.61, 95% CI 1.09-2.37), being admitted before the change in study description (OR 0.39, 95% CI 0.31-0.48), and the staff member who consented the patient (p <0.001); ethnicity was not a significant factor. Conclusions: Rectal swabs are recommended for the detection of ESBL-E colonization. Staff and patient factors influence whether patients participate in prevalence studies, which may skew their findings. (C) 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.