Individual- and community-level risk factors for ESBL Enterobacteriaceae colonization identified by universal admission screening in London.

OBJECTIVES: We evaluated risk factors for gastrointestinal carriage of Enterobacteriaceae which produce extended-spectrum ß-lactamases (ESBL-E), including individual-level variables such as antibiotic use and foreign travel, and community-level variables such as housing and deprivation. METHODS: In an observational study in 2015, all patients admitted to a London hospital group were approached to be screened for ESBL-E carriage using rectal swabs for 4 months. Patients completed a risk factor questionnaire. Those with a residential postcode in the local catchment area were linked to a database containing community-level risk factor data. Risk factors for ESBL-E carriage were determined by binary logistic regression. RESULTS: Of 4006 patients, 360 (9.0%) carried ESBL-E. Escherichia coli was the most common organism (77.8%), and CTX-M-type ESBLs were the most common genes (57.9% CTX-M-15 and 20.7% CTX-M-9). In multivariable analysis, risk factors for phenotypic ESBL-E among the 1633 patients with a residential postcode within the local catchment area were: travel to Asia (OR 4.4, CI 2.5-7.6) or Africa (OR 2.4, CI 1.2-4.8) in the 12 months prior to admission, two or more courses of antibiotics in the 6 months prior to admission (OR 2.0, CI 1.3-3.0), and residence in a district with a higher-than-average prevalence of overcrowded households (OR 1.5, CI 1.05-2.2). . CONCLUSIONS: Both individual and community variables were associated with ESBL-E carriage at hospital admission. The novel observation that household overcrowding is associated with ESBL-E carriage requires confirmation, but raises the possibility that targeted interventions in the community could help prevent transmission of antibiotic-resistant Gram-negative bacteria.

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

OBJECTIVES: We evaluated 'pre-laboratory' factors associated with the detection of extended spectrum ß-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.