Similarities in Virulence and Extended Spectrum Beta-Lactamase Gene Profiles among Cefotaxime-Resistant Escherichia coli Wastewater and Clinical Isolates.

The World Health Organization has identified antibiotic resistance as one of the largest threats to human health and food security. In this study, we compared antibiotic resistance patterns between ESBL-producing Escherichia coli from human clinical diseases and cefotaxime-resistant environmental strains, as well as their potential to be pathogenic. Antibiotic susceptibility was tested amongst clinical isolates (n = 11), hospital wastewater (n = 22), and urban wastewater (n = 36, both influent and treated effluents). Multi-drug resistance predominated (>70%) among hospitalwastewater and urban wastewater influent isolates. Interestingly, isolates from clinical and urban treated effluents showed similar multi-drug resistance rates (~50%). Most hospital wastewater isolates were Phylogroup A, while clinical isolates were predominately B2, with a more diverse phylogroup population in urban wastewater. ESBL characterization of cefotaxime-resistant populations identified blaCTX-M-1 subgroup as the most common, whereby blaKPC was more associated with ceftazidime and ertapenem resistance. Whole-genome sequencing of a carbapenemase-producing hospital wastewater E. coli strain revealed plasmid-mediated blaKPC-2. Among cefotaxime-resistant populations, over 60% of clinical and 30% of treated effluent E. coli encoded three or more virulence genes exhibiting a pathogenic potential. Together, the similarity among treated effluent E. coli populations and clinical strains suggest effluents could serve as a reservoir for future multi-drug resistant E. coli clinical infections.

Antibiotic resistance patterns of Escherichia coli isolates from the clinic through the wastewater pathway.

Antimicrobial resistance (AMR) remains one of the leading global health threats. This study compared antimicrobial resistance patterns among E. coli isolates from clinical uropathogenic Escherichia coli (UPEC) to hospital wastewater populations and throughout an urban wastewater treatment facility - influent, pre- and post-chlorinated effluents. Antibiotic susceptibility of 201 isolates were analyzed against eleven different antibiotics, and the presence of twelve antibiotic resistant genes and type 1 integrase were identified. AMR exhibited the following pattern: UPEC (46.8%) > hospital wastewater (37.8%) > urban post-chlorinated effluent (27.6%) > pre-chlorinated effluent (21.4%) > urban influent wastewater (13.3%). However, multi-drug resistance against three or more antimicrobial classes was more prevalent among hospital wastewater populations (29.7%) compared to other sources. E. coli from wastewaters disinfected with chlorine were significantly correlated with increased trimethoprim-sulfamethoxazole resistance in E. coli compared to raw and treated wastewater populations. blaCTX-M-1 group was the most common extended spectrum beta-lactamase in E. coli from hospital wastewater (90%), although UPEC strains also encoded blaCTX-M-1 group (50%) and blaTEM (100%) genes. Among tetracycline-resistant populations, tetA and tetB were the only resistance genes identified throughout wastewater populations that were associated with increased phenotypic resistance. Further characterization of the E. coli populations identified phylogroup B2 predominating among clinical UPEC populations and correlated with the highest AMR, whereas the elevated rate of multi-drug resistance among hospital wastewater was mostly phylogroup A. Together, our findings highlight hospital wastewater as a rich source of AMR and multi-drug resistant bacterial populations.