Diversity of β‑lactamase‑encoding genes in wastewater: bacteriophages as reporters

BLANCO FERNÁNDEZ, MARÍA DOLORES; POWER, PABLO; CAMMARATA, ROBERTINA VIVIANA; MBAYED, VIVIANA ANDREA; BARRIOS, MELINA ELIZABETH; TORRES, CAROLINA

ARCHIVES OF VIROLOGY

SPRINGER WIEN

Lugar: Viena; Año: 2021

0304-8608

A reservoir of antibiotic resistance genes (ARGs) is present in pathogenic, commensal, and environmental bacteria as wellas in mobile genetic elements, including bacteriophages. Wastewater treatment plants (WWTPs) are considered hotspots forthe spread of ARGs. The aim of this work was to analyze the diversity of the highly prevalent ARGs blaCTX-M and blaTEMin bacterial and bacteriophage fractions associated with human and animal environments through the study of urban wasteand animal residues discharged into WWTPs to provide information about the composition and maintenance of the currentresistome in Buenos Aires, Argentina. The results showed that a putative extended-spectrum variant of the blaTEM gene wasthe most frequently detected, with blaTEM-116 being the most prevalent, while a recently described type, blaTEM-229, was alsofound. In the bacteriophage fraction, we detected blaCTX-M genes from four out of the five clusters described. The detection ofblaCTX- M-9-like and blaCTX-M-25-like genes was unexpected based on surveys of the ARGs from clinical pathogens circulatingregionally. The finding of divergent blaCTX-M sequences associated with previously reported environmental genes argues infavor of the natural environment as a reservoir of resistance genes. ARGs were detected in bacteriophages as frequently asin bacterial communities, and furthermore, the blaCTX-M genes were more diverse in the bacteriophage fraction. Bacteriophagesmight therefore play a role in the spread of ARGs in the environment, but they might also be used as ?reporters? formonitoring circulating ARGs.