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

Abstract

Wastewater sampling could be a low-cost strategy for assessing patterns of antibacterial resistance across urban populations. We aimed to quantify fluoroquinolone-resistant (FQ-R) Enterobacterales, third-generation cephalosporin-resistant (3GC-R) Enterobacterales, carbapenem-resistant Enterobacterales, and theblaCTX-M-15andblaKPCgenes in influent wastewater from 12 diverse sewersheds across metro Atlanta over 2 seasons; examine associations between culture- and digital PCR-based outcomes; and investigate relationships between sewersheds’ sociodemographic characteristics and concentrations of AR bacteria in wastewater. FQ-R Enterobacterales, 3GC-REscherichia coli, and 3GC-RKlebsiella,Enterobacter, orCitrobacterspp. (KEC) were detected in 79-94% of samples (n=34), with concentrations differing among sewersheds. Carbapenem-resistantE. coliand KEC were not reliably detected. TheblaCTX-M-15gene was detected in every sample, and we detected trends towards an association with 3GC-RE. coliand KEC, suggesting potential utility of this gene as a monitoring target. TheblaKPCgene was detected in every sample despite carbapenem-resistantE. coliand KEC not reliably being detected, suggesting it is not an appropriate indicator for these bacteria. After accounting for season, repeated measures, and potential healthcare inputs, we found that sewersheds with higher proportions of crowded households, Hispanic, non-Hispanic Asian, and individuals speaking a language other than English at home had higher flow-normalized concentrations of FQ-R Enterobacterales, 3GC-RE. coliand/or KEC in their wastewater. Comparisons with human data are needed to determine how well sociodemographic patterns observed through wastewater mirror trends in the human population.ImportanceWastewater sampling is a popular tool for the surveillance of health-related targets. Previous studies have demonstrated increases in antibiotic resistance among wastewater-derived fecal pathogens that match temporal trends in geographically-matched patient populations, indicating utility for assessing population-level patterns. Few studies have studied wastewater to examine antibiotic resistance patterns within a city, or to identify sociodemographic characteristics associated with higher concentrations of antibiotic-resistant bacteria in wastewater from certain neighborhoods. We tested municipal wastewater from 12 diverse sewersheds across metro Atlanta across two seasons. We identified significant differences in antibiotic-resistant bacterial concentrations across sewersheds, and after accounting for season, repeated sampling, and potential inputs from healthcare facilities, we found these differences were associated with community characteristics like living conditions and language. Overall, given that clinical surveillance is unlikely to be representative of the US population due to unequal healthcare access, wastewater sampling merits consideration as a novel approach for antibiotic resistance surveillance.