Nationwide surveillance reveals frequent detection of carbapenemase-producing Enterobacterales in Dutch municipal wastewater

Abstract

Carbapenemase-producing Enterobacterales (CPE) pose a threat to public health necessitating restriction of further spread. Tools to efficiently monitor the prevalence of these still relatively rare resistant bacteria and insight in routes of dissemination are pivotal for the development of prevention strategies. By analysis of untreated and treated wastewater from 100 municipal wastewater treatment plants (WWTPs) together serving over 40% of the Dutch population, this study investigated both the distribution of CPE in the Dutch population, and WWTPs as a source of CPE in the aquatic environment.CPE were detected at 89% of the WWTPs, in 87 influents and 53 effluents. Overall, 15 different CPE-types were detected based on species and carbapenemase gene. The most widely distributed were E. coli carrying blaOXA-48-like genes, which were detected at 88 WWTPs including small WWTPs without connected health care institutions (HCI). BlaOXA-48-like-positive-K. pneumoniae, blaNDM- or blaKPC-positive E. coli, and blaNDM- or blaKPC-positive K. pneumoniae were detected at 33, 20, and 14 WWTPs, respectively. Mean influent and effluent CPE concentrations were 7.9×102 cfu/l and 11 cfu/l. The total daily number of CPE discharged by the 100 WWTPs was estimated to be 2.2×1011 cfu. In multivariate analysis, CPE concentrations in untreated wastewater were positively associated with WWTP size and E. coli concentrations, but not with the presence of HCI. Based on the total number of CPE (9.7×1012 cfu) and ESBL-E. coli (2.41015 cfu) in influents, and a prevalence of approximately 5% in the Dutch population for ESBL-E. coli, the prevalence of CPE in the Dutch population was roughly estimated to be 0.02%.Wastewater surveillance is an efficient tool to monitor the distribution of CPE in the population at a national level and may supplement human surveillance data. CPE are emitted to the aquatic environment with treated wastewater and associated public health risks need to be determined.