Monitoring ESBL-Escherichia coliin Swiss wastewater between November 2021 and November 2022: insights into population carriage

Abstract

BackgroundAntimicrobial resistance (AMR) poses a global health threat, causing millions of deaths annually, with expectations of increased impact in the future. Wastewater surveillance offers a cost-effective, non-invasive tool to understand AMR carriage trends within a population.AimWe monitored extended-spectrum β-lactamase producingEscherichia coli(ESBL-E. coli) weekly in influent wastewater from six wastewater treatment plants (WWTPs) in Switzerland (November 2021 to November 2022) to investigate spatio-temporal variations, explore correlations with environmental variables, develop a predictive model for ESBL-E. colicarriage in the community, and detect the most prevalent ESBL-genes.MethodsWe cultured total and ESBL-E. coliin 300 wastewater samples to quantify daily loads and percentage of ESBL-E. coli. Additionally, we screened 234 ESBL-E. coliisolates using molecular-methods for the presence of 18 ESBL-gene families.ResultsWe found a population-weighted mean percentage of ESBL-E. coliof 1.9% (95%CI 1.8%, 2%) across all sites and weeks, which can inform ESBL-E. colicarriage. Concentrations of ESBL-E. colivaried across WWTPs and time, with higher values observed in WWTPs serving larger populations. Recent precipitations (previous 24-/96-hours) showed no significant association with ESBL-E. coli, while temperature occasionally had a moderate impact (p<0.05, correlation coefficients approximately 0.40) in some locations. We identifiedblaCTX-M-1,blaCTX-M-9andblaTEMas the predominant ESBL-gene families.ConclusionsOur study demonstrates that wastewater-based surveillance of culturable ESBL-E. coliprovides insights into AMR trends in Switzerland and may also inform resistance. These findings establish a foundation for long-term, nationally established monitoring protocols and provide information that may help inform targeted public health interventions.

Using wastewater sampling to investigate community-level differences in antibacterial resistance in a major urban center, USA

“…24 To our knowledge, this is the first study to report specific sociodemographic characteristics that may be associated with higher concentrations of clinically-relevant AR bacteria in wastewater. If reflective of the human burden of AR bacteria, 25 these data may be informative for adapting interventions in community settings. Comparisons to human conization and infection data are needed before wastewater data are leveraged to inform public health practice in this setting.…”

“…A recent Swiss study estimated that sampling at least once per month results in a 95% CI width below ±0.5%. 25 Second, we did not specifically account for recent rainfall or surface temperature in our statistical analyses, although we did account for sampling round in all statistical analyses in an effort to account for differing meteorological conditions across timepoints. Recent studies have found mixed impacts of recent rainfall and temperature on AR Enterobacterales concentrations in wastewater.…”

“…Recent studies have found mixed impacts of recent rainfall and temperature on AR Enterobacterales concentrations in wastewater. 25,45–47 Third, we were unable to consider physical differences in sewer systems, including piping material, conductivity, or the presence of biofilms, that could influence replication of AR Enterobacterales, their persistence and viability in sewers, or their ability to exchange ARGs. 45 These features could have theoretically influenced differences in AR Enterobacterales concentrations in wastewater, although given that sewershed population size (approximated in our study by flow rate) is a major predictor of ARG and AR bacteria concentrations in wastewater, 31,48 inputs from community and healthcare settings likely exert greater influence.…”