One decade of point-prevalence surveys for carriage of extended-spectrum beta-lactamase-producing enterobacterales: whole genome sequencing based prevalence and genetic characterization in a large Dutch teaching hospital from 2013 to 2022.

Objectives: To determine the prevalence, trends, and potential nosocomial transmission events of the hidden reservoir of rectal carriage of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E).

Methods: From 2013 to 2022, yearly point prevalence surveys were conducted in a large Dutch teaching hospital. On the day of the survey, all admitted patients were screened for ESBL-E rectal carriage using peri-anal swabs and a consistent and sensitive selective culturing method. All Enterobacterales phenotypically suspected of ESBL production were analysed using whole genome sequencing for ESBL gene detection and clonal relatedness analysis.

Results: On average, the ESBL-E prevalence was 4.6% (188/4,119 patients), ranging from 2.1 to 6.6% per year. The ESBL-prevalence decreased on average 5.5% per year. After time trend correction, the prevalence in 2016 and 2020 was lower compared to the other year. Among the ESBL-E, Escherichia coli (80%) and CTX-M genes (85%) predominated. Potential nosocomial transmission events could be found in 5.9% (11/188) of the ESBL-E carriers.

Conclusions: The ESBL-E rectal carriage prevalence among hospitalized patients was 4.6% with a downward trend from 2013 to 2022. The decrease in ESBL-E prevalence in 2020 could have been due to the COVID-19 pandemic and subsequent countrywide measures as no nosocomial transmission events were detected in 2020. However, the persistently low ESBL-E prevalences in 2021 and 2022 suggest that the decline in ESBL-E prevalence goes beyond the COVID-19 pandemic, indicating that overall ESBL-E carriage rates are declining over time. Continuous monitoring of ESBL-E prevalence and transmission rates can aid infection control policy to keep antibiotic resistance rates in hospitals low.