AUTHOR=Gómez-Sanz Elena , Bagutti Claudia , Roth Jan A. , Alt Hug Monica , García-Martín Ana B. , Maurer Pekerman Laura , Schindler Ruth , Furger Reto , Eichenberger Lucas , Steffen Ingrid , Egli Adrian , Hübner Philipp , Stadler Tanja , Aguilar-Bultet Lisandra , Tschudin-Sutter Sarah 

TITLE=Spatiotemporal dissemination of ESBL-producing Enterobacterales in municipal sewer systems: a prospective, longitudinal study in the city of Basel, Switzerland

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1174336

DOI=10.3389/fmicb.2023.1174336

ISSN=1664-302X

ABSTRACT=<sec><title>Background</title><p>The contribution of community and hospital sources to the transmission of extended-spectrum β-lactamase producing Enterobacterales (ESBL-PE) remains elusive.</p></sec><sec><title>Aim</title><p>To investigate the extent of community dissemination and the contribution of hospitals to the spread of ESBL-PE by exploring their spatiotemporal distribution in municipal wastewater of the central European city of Basel.</p></sec><sec><title>Methods</title><p>Wastewater samples were collected monthly for two consecutive years throughout Basel, Switzerland, including 21 sites across 10 postcode areas of the city collecting either community wastewater (urban sites, <italic>n</italic> = 17) or community and hospital wastewater (mixed sites, <italic>n</italic> = 4). Presumptive ESBL-PE were recovered by selective culture methods. Standard methodologies were applied for species identification, ESBL-confirmation, and quantification.</p></sec><sec><title>Results</title><p>Ninety-five percent (477/504) of samples were positive for ESBL-PE. Among these isolates, <italic>Escherichia coli</italic> (85%, 1,140/1,334) and <italic>Klebsiella pneumoniae</italic> (11%, 153/1,334) were most common. They were recovered throughout the sampling period from all postcodes, with <italic>E. coli</italic> consistently predominating. The proportion of <italic>K. pneumoniae</italic> isolates was higher in wastewater samples from mixed sites as compared to samples from urban sites, while the proportion of <italic>E. coli</italic> was higher in samples from urban sites (<italic>p</italic> = 0.003). Higher numbers of colony forming units (CFUs) were recovered from mixed as compared to urban sites (median 3.2 × 10<sup>2</sup> vs. 1.6 × 10<sup>2</sup> CFU/mL). <italic>E. coli</italic>-counts showed moderate correlation with population size (rho = 0.44), while this correlation was weak for other ESBL-PE (rho = 0.21).</p></sec><sec><title>Conclusion</title><p>ESBL-PE are widely spread in municipal wastewater supporting that community sources are important reservoirs entertaining the spread of ESBL-PE. Hospital-influenced abundance of ESBL-PE appears to be species dependent.</p></sec>