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

Wastewater surveillance could be a low-cost strategy for assessing patterns of antibiotic resistance across urban populations. We quantified fluoroquinolone-resistant (FQ-R) Enterobacterales, third-generation cephalosporin-resistant (3GC-R) Enterobacterales, carbapenem-resistant Enterobacterales, and the blaCTX-M-group 1 and blaKPC genes in influent wastewater from 12 diverse sewersheds across metro Atlanta over two seasons; examined associations between culture- and digital PCR-based outcomes; and investigated relationships between sewersheds' sociodemographic characteristics and concentrations of antibiotic-resistant bacteria in wastewater. FQ-R Enterobacterales, 3GC-R Escherichia coli, and 3GC-R Klebsiella, Enterobacter, or Citrobacter spp. (KEC) were detected in 79%-94% of samples (n = 34), with concentrations differing among sewersheds. Carbapenem-resistant E. coli and KEC were not reliably detected. The blaCTX-M-group 1 gene was detected in every sample, and we detected trends toward an association with 3GC-R E. coli and KEC, suggesting potential utility of this gene as a monitoring target. The blaKPC gene was detected in every sample despite carbapenem-resistant E. coli and KEC not being reliably 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-R E. coli and/or KEC in their wastewater. Given the potential for confounding, comparisons with human data are needed to determine how well sociodemographic patterns observed through wastewater mirror trends in the population.IMPORTANCEWastewater surveillance is a popular tool for the monitoring 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. We tested municipal wastewater from 12 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 surveillance merits consideration as a novel approach for antibiotic resistance surveillance.