# Mangrove Ecosystems as Reservoirs of Antibiotic Resistance Genes: A Narrative Review

## TL;DR

Mangrove ecosystems are important reservoirs of antibiotic resistance genes, especially near aquaculture and urban areas, and they play a role in spreading these genes through horizontal transfer.

## Contribution

This review synthesizes global findings on antibiotic resistance genes in mangroves, emphasizing their role as reservoirs and the influence of environmental factors.

## Key findings

- ARGs like tetracycline, sulfonamide, and multidrug resistance genes are widespread in mangroves near aquaculture and urban areas.
- Metagenomic studies show diverse resistomes with mobile genetic elements, suggesting high potential for horizontal gene transfer.
- Environmental factors such as sediment type, organic matter, and salinity influence ARG abundance and distribution.

## Abstract

Background: Mangrove ecosystems are critical coastal environments providing ecological services and acting as buffers between terrestrial and marine systems. Rising antibiotic use in aquaculture and coastal agriculture has led to the dissemination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in these habitats. Aim: This narrative review aims to synthesize current knowledge on the prevalence, diversity, and environmental drivers of ARGs in mangrove ecosystems, highlighting their role as reservoirs and the potential for horizontal gene transfer. Methods: Studies published up to September 2024 were identified through PubMed, Scopus, Web of Science, and Google Scholar. Inclusion criteria focused on ARGs and ARB in mangrove sediments, water, and associated biota. Data on ARG prevalence, microbial community composition, detection methods, and environmental factors were extracted and narratively synthesized. Results: Seventeen studies from Asia, South America, and Africa were included. ARGs conferring resistance to tetracyclines, sulfonamides, β-lactams, and multidrug resistance were found to be widespread, particularly near aquaculture and urban-influenced areas. Metagenomic analyses revealed diverse resistomes with frequent mobile genetic elements, indicating high potential for horizontal gene transfer. Environmental factors, including sediment type, organic matter, and salinity, influenced ARG abundance and distribution. Conclusions: Mangrove ecosystems act as both reservoirs and natural buffers for ARGs. Sustainable aquaculture practices, continuous environmental monitoring, and integrated One Health approaches are essential to mitigate ARG dissemination in these sensitive coastal habitats.