Distribution of β-Lactamase Resistance Genes in the Environment: A Systematic Review

The pervasive antimicrobial resistance (AMR) propagation in the environment constitutes a global concern, with wastewater being identified as a considerable contributor to the dissemination of resistance determinants. Introducing antibiotics and other pollutants into natural ecosystems via human activities has been considered a key factor in exacerbating this issue. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and aims to assess the scientific literature published within the last ten years regarding the presence and diversity of antimicrobial resistance genes, especially β-lactamase-encoding genes, in environmental samples. A synthesis of data from peer-reviewed studies was conducted, investigating different environmental matrices—including water, soil, and sludge—using molecular methods for antibiotic resistance gene (ARG) detection and monitoring. This analysis underscores the commonly utilised molecular methods, such as polymerase chain reaction-based assays and next-generation sequencing. Thus, we show a high prevalence and diversity of β-lactamase genes in different environments, thereby underlining the crucial role of wastewater as an AMR reservoir and vector. Additionally, the analysis identifies crucial gaps in research, including the standardisation of sampling and analysis protocols, as well as limited surveillance. Research has indicated the requirement for the environment to be monitored and for the development of unambiguous techniques to track and prevent the propagation of antibiotic resistance from the environment into human-associated ecosystems. This information contributes to a more nuanced understanding of AMR’s dynamics in the environment and supports the development of improved monitoring and mitigation strategies.