Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
To facilitate multisectoral antimicrobial resistance (AMR) surveillance, the World Health Organization (WHO) has proposed an integrated culture-based surveillance methodology for direct quantification of extended-spectrum-β-lactam resistant (ESBL) Escherichia coli (E-Ec) in environmental hotspots and for detection in other ‘One Health’ hotspots. We evaluated six candidate ESBL-selective agar media for E-Ec detection and quantification, quantification of E-Ec as a proportion of total E. coli, and presumptive identification and characterization of E-Ec in raw sewage, poultry waste, and urban surface water analyses. E-Ec quantification used standard membrane filtration (surface water) and spread plating (other samples) methods. MALDI-TOF and VITEK analyses verified isolates’ identity and AMR profiles. Results showed Tryptone Bile Glucoronic (TBX) medium was most sensitive for E-Ec quantification overall (though not significantly so) and significantly more accurate in presumptively identifying and characterizing isolates. These findings support adoption of this AMR indicator system using TBX to provide integrated, accurate AMR surveillance methods globally.