# Antimicrobial Resistance Elements in Coastal Water of Llanquihue Lake, Chile

## TL;DR

This study explores antimicrobial resistance in Chile's Llanquihue Lake, finding diverse bacteria and resistance genes linked to human antibiotic use.

## Contribution

The first report of potential health-threatening genomic elements in Chile's coastal waters, emphasizing the One Health concept.

## Key findings

- A high diversity of microorganisms, including human and animal pathogens, was found in Llanquihue Lake.
- Antimicrobial resistance genes (ARGs) conferring resistance to macrolides, beta-lactams, and tetracyclines were detected.
- ARGs were identified in mobile DNA elements, suggesting potential for gene transfer between microorganisms.

## Abstract

Antimicrobial resistance has been stated to be a global health problem. In Chile, the use of antibiotics should be declared by medical prescription, but it is unknown what happens to the drugs once the treatment ends. Among the possibilities for their disposal are the trash or the drain; regardless of which scenario arises, antibiotics could accumulate in the environment, stimulating the emergence of antimicrobial resistance mechanisms and their transfer between microorganisms. Unfortunately, sometimes wastewater ends up in bodies of water, due to the dragging of elements by rain, or by the presence of illegal water discharges. In this work, shotgun metagenomics was used to elucidate the functional and microbial composition of biohazard elements in the bay of Puerto Varas City, Chile. As expected, a high diversity of microorganisms was found, including bacterial elements described as human or animal pathogens. Also, a diverse repertory of antimicrobial resistant genes (ARGs) was detected, which confers mainly resistance to macrolides, beta-lactams, and tetracyclines, consistent with the families of antibiotics most used in Chile. Similar ARGs were identified in DNA mobile elements. In addition, we tested the antimicrobial susceptibility in 14 bacterial strains isolated from Llanquihue Lake. This is the first report of the presence of genomic elements that could constitute a health problem, considering the importance of the interconnection between environmental, animal, and human health, a concept known as One Health.