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

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

ARCHIVES OF VIROLOGY

SPRINGER WIEN

Año: 2021

0304-8608

A reservoir of antibiotic resistance genes (ARGs) is present in pathogenic, commensal and environmental bacteria as well as in mobile genetic elements, including bacteriophages. The wastewater treatment plants (WWTPs) are considered as hotspots for spreading of ARGs. The aim of this work was to analyze the diversity of the highly prevalent ARGs blaCTX-M and blaTEM in bacterial and bacteriophage fractions associated with human and animal environments, through the study of urban wastes and animal residues discharged into WWTPs, to contribute to the knowledge of the composition and maintenance of the current resistome in Buenos Aires, Argentina. According to the results, putative extended-spectrum variant of blaTEM genes were the most frequently detected, being blaTEM-116 the most prevalent, while a recently described type, blaTEM-229, was also found. In the bacteriophage fraction, we detected blaCTX-M genes from 4 out of the 5 clusters described. The detection of blaCTX- M-9-like and blaCTX-M-25-like genes was unexpected according to the regional circulating ARGs from clinical pathogens. The finding of blaCTX-M divergent sequences associated with previous reported environmental genes argues in favor of the natural environments as reservoirs of resistance. ARGs were detected among bacteriophages as frequently as among bacterial communities and even more, the blaCTX-M genes were more diverse in the bacteriophage fraction. The bacteriophages might have a role in the spread of ARGs in the environment, but they might also be used as the ?reporters? of the circulating ARGs.