Resistência aos antimicrobianos em Escherichia coli e Klebsiella pneumoniae isoladas de efluentes hospitalar e municipal: evidências da epidemiologia baseada em esgoto

Abstract

Antimicrobial resistance (AMR) in wastewater is a One Health challenge, as it integrates selective pressures from human, animal, and environmental health, favoring the persistence of multidrug-resistant bacteria and resistance genes. This dissertation is organized into two chapters: Chapter 1 discusses AMR, sewer networks and wastewater treatment plants (WWTPs) as hotspots for selection and horizontal gene transfer, wastewater-based epidemiology (WBE) as a population-level surveillance approach, and the role of whole-genome sequencing (WGS) and the mobilome/plasmidome. Chapter 2 investigated extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and carbapenemase-producing Klebsiella pneumoniae in municipal influent from the Uberabinha WWTP (Dec/2024–Nov/2025; n=18) and hospital wastewater from the Clinical Hospital of the Federal University of Uberlândia (HC-UFU) (Feb/2025–Nov/2025; n=10), using 24-h composite samples, culture on selective chromogenic media, identification and antimicrobial susceptibility testing (VITEK-2), classification as multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR), and WGS-based resistome/plasmidome analyses. The proportion of Enterobacteriaceae under ESBL selection was higher in HC-UFU (median 11.5%) than in the municipal WWTP (median 5.1%; p<0.001), whereas no difference was observed for carbapenemase selection (median 1.1% in both). A total of 280 colonies were recovered: on ESBL medium, E. coli predominated in the WWTP (52/90; 57.8%) but was rare in HC-UFU (2/52; 3.84%), where Citrobacter freundii was most frequent (17/50; 34%); on carbapenemase-selective medium, K. pneumoniae was the most frequent species at both sites (WWTP: 54/90; 60% | HC-UFU: 27/50; 54%). WWTP E. coli were 98.1% MDR and 13.5% XDR, with no PDR, and retained susceptibility to carbapenems and tigecycline. K. pneumoniae showed greater severity in HC-UFU (88.9% XDR) than in the WWTP (61.1% XDR), including 1.9% PDR in municipal wastewater; meropenem/ertapenem resistance reached 92.59% in HC-UFU and 33.33% in the WWTP. WGS confirmed blaCTX-M genes in E. coli (notably blaCTX-M-55) and blaCTX-M-15 in K. pneumoniae, as well as blaKPC-2 and blaNDM; rmtB and mcr-9 were exclusive to hospital wastewater, and IncF and Col-type replicons were frequent. Overall, these findings highlight municipal and hospital wastewaters as reservoirs of MDR/XDR profiles and support WBE as a strategic tool for AMR surveillance and for informing public policies on wastewater treatment.