Antibiotic and heavy metal resistance co-selection in environmental bacteria is a critical area of research due to the increasing prevalence of antibiotic resistance genes (ARGs) and the role of heavy metals in their dissemination. This review summarizes recent evidence on the mechanisms of co-selection between metals and antibiotics, highlighting the genetic models of co-resistance, cross-resistance, and co-regulation. Heavy metals, such as cadmium, copper, and zinc, are prevalent in environmental niches and often co-occur with antibiotics, leading to the co-selection of resistance genes. These genes are frequently found on mobile genetic elements (MGEs) like plasmids, transposons, and integrons, which facilitate horizontal gene transfer (HGT). The co-selection of resistance genes is influenced by factors such as the concentration of metals, their bioavailability, and environmental conditions. The review discusses the mechanisms of resistance, including efflux, chemical modification, and sequestration, and highlights the role of MGEs in the mobilization of resistance genes. The review also emphasizes the importance of understanding the molecular aspects of co-selection to develop effective strategies for mitigating the spread of antibiotic resistance. Key findings include the correlation between heavy metals and ARGs, the role of MGEs in resistance gene transfer, and the need for further research to clarify the mechanisms of co-selection. The review concludes with a discussion of the current understanding of co-selection and the gaps that remain in knowledge.Antibiotic and heavy metal resistance co-selection in environmental bacteria is a critical area of research due to the increasing prevalence of antibiotic resistance genes (ARGs) and the role of heavy metals in their dissemination. This review summarizes recent evidence on the mechanisms of co-selection between metals and antibiotics, highlighting the genetic models of co-resistance, cross-resistance, and co-regulation. Heavy metals, such as cadmium, copper, and zinc, are prevalent in environmental niches and often co-occur with antibiotics, leading to the co-selection of resistance genes. These genes are frequently found on mobile genetic elements (MGEs) like plasmids, transposons, and integrons, which facilitate horizontal gene transfer (HGT). The co-selection of resistance genes is influenced by factors such as the concentration of metals, their bioavailability, and environmental conditions. The review discusses the mechanisms of resistance, including efflux, chemical modification, and sequestration, and highlights the role of MGEs in the mobilization of resistance genes. The review also emphasizes the importance of understanding the molecular aspects of co-selection to develop effective strategies for mitigating the spread of antibiotic resistance. Key findings include the correlation between heavy metals and ARGs, the role of MGEs in resistance gene transfer, and the need for further research to clarify the mechanisms of co-selection. The review concludes with a discussion of the current understanding of co-selection and the gaps that remain in knowledge.