Extended-Spectrum β-Lactamase and Carbapenemase Genes are Substantially and Sequentially Reduced during Conveyance and Treatment of Urban Sewage

Abstract

Urban wastewater systems (UWSs) are a main receptacle of excreted antibiotic resistance genes (ARGs) and their host microorganisms. However, we lack integrated and quantitative observations of the occurrence of ARGs in the UWS to characterize the sources and identify processes that contribute to their fate. We sampled the UWSs from three medium-size cities in Denmark, Spain, and the United Kingdom and quantified 70 clinically important extended-spectrum β-lactamase and carbapenemase genes along with the mobile genetic elements and microbial communities. Results from all three countries showed that sewageespecially from hospitalscarried substantial loads of ARGs (106–107 copies per person equivalent), but these loads progressively declined along sewers and through sewage treatment plants, resulting in minimal emissions (101–104 copies per person equivalent). Removal was primarily during sewage conveyance (65 ± 36%) rather than within sewage treatment (34 ± 23%). The extended-spectrum β-lactamase and carbapenemase genes were clustered in groups based on their persistence in the UWS compartments. The less-persistent groups were associated to putative host taxa (especially Enterobacteriaceae and Moraxellaceae), while the more persistent groups appeared horizontally transferred and correlated significantly with total cell numbers and mobile genetic elements. This documentation of a substantial ARG reduction during sewage conveyance provides opportunities for antibiotic resistance management and a caution for sewage-based antibiotic resistance surveillance.

Novel municipal sewage-associated bacterial genomes and their potential in source tracking

“…The abundance of β-lactamases across the inoculum samples was substantially higher (7-15 times) compared to the control (Figure 5). This result was consistent with both our expectations and the literature regarding heightened ARG abundance within collection systems (74). Specifically, others have reported substantial abundances of βlactamase OXA genes on both Campylobacteraceae and Aeromonadaceae clades in sewage (75).…”

Research needs for optimising wastewater-based epidemiology monitoring for public health protection

“…Due to the higher antibiotic usage in hospital settings, previous studies have investigated the impact of hospital wastewater mixing with community wastewater on resistomes, with mixed results (Islam et al 2017;Lamba et al 2017;Buelow et al 2018Buelow et al , 2020Quintela-Baluja et al 2019Li et al 2021). Future work should focus on evaluating the factors that affect the influence of sewer conditions and inputs to the sewer systems that impact measures of AMR.…”

Clinically Relevant β-Lactam Resistance Genes in Wastewater Treatment Plants

“…Due to the global spread of class A β-lactamases, it is a commonly, or even predominantly, detected group in WWTPs ( Table 1 ). In a multi-national study of WWTPs from Denmark, Spain, and the United Kingdom (UK) with high-throughput qPCR used, these β-lactamases was leading, accounting for 70% of all detected bla genes [ 65 ]. Among them, the most relevant were two groups linked with ESBL and KPC enzymes.…”

“…In some studies, bla TEM was predominant, e.g., in an Irish study [ 86 ], as well as in Colombia [ 87 ], Poland and Portugal [ 9 , 88 ], Belgium [ 89 ], the US [ 90 ], and Africa [ 91 ]. Another significant group representing the KPC family encoded by bla KPC genes was detected in numerous WWTPs from European [ 65 , 69 , 89 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ], as well as from American [ 90 , 102 , 103 , 104 ], African [ 72 , 91 , 105 ], and Asian countries [ 106 , 107 ]. Moreover, analysis of reviewed articles, especially those using developed techniques as high-throughput qPCR, whole-genome sequencing, or metagenomics, shows a high variety of detected genes of the discussed β-lactamases, not only representing bla CTX-M , bla SHV , bla TEM , and bla KPC families, but also others less frequently associated with public health, i.e., BEL, cfxA, GES, PER, SME, VEB, and others [ 65 , 92 , 96 , 102 , 107 , 108 , 109 , 110 , 111 ].…”