Antimicrobial resistance in coastal waters of Latin America: current knowledge and challenges

Antimicrobial resistance (AMR) is one of the most critical threats to global public health, and in aquatic ecosystems, coastal environments act as reservoirs and transmission routes that remain underexplored. In Latin America, these ecosystems are subject to strong anthropogenic pressures from urban and hospital discharges, agricultural and aquaculture activities, and tourism, within a context of limited wastewater treatment coverage. To synthesize the available evidence, we reviewed studies published between 1991 and 2025 addressing the occurrence of resistant bacteria and resistance genes in coastal waters of the region. A total of 48 articles were analyzed, with research concentrated in Brazil, while extensive areas of Central America and the Caribbean lack data. Most studies relied on phenotypic approaches, although in recent years the use of molecular tools and, to a lesser extent, metagenomics has increased. Multidrug-resistant bacteria of clinical importance, such as Escherichia coli, Enterococcus, Vibrio, and Staphylococcus, including pan-resistant strains, have been reported, along with resistance genes related to extended-spectrum β-lactamases, sulfonamides, tetracyclines, and mcr variants of colistin. These findings reflect the influence of multiple contamination sources and highlight potential risks to human health, particularly in recreational and productive environments. Despite growing interest, important knowledge gaps remain, including limited geographic coverage, uneven methodological approaches, and the lack of standardized protocols that would enable regional comparisons. Strengthening environmental surveillance, integrating genomic tools, and promoting cooperation under the One Health framework are urgent steps to reduce the spread of antimicrobial resistance in Latin American coastal ecosystems and to safeguard both environmental and human health.