Background/Objectives: Hospital wastewater is a complex effluent containing a wide range of biological and chemical contaminants, including pharmaceuticals, pathogens, and antimicrobial resistance determinants. These discharges pose a growing threat to aquatic ecosystems and public health, particularly in regions where wastewater treatment is insufficient. This study aimed to characterize the chemical and microbiological composition of untreated effluent from a tertiary care hospital in southern Chile, focusing on contaminants of emerging concern. Methods: Wastewater samples were collected at the hospital outlet before any treatment. The presence of two commonly used pharmaceutical compounds, paracetamol and amoxicillin, was quantified using high-performance liquid chromatography (HPLC). Bacterial isolation was performed using selective media, and antibiotic susceptibility testing was conducted via the disk diffusion method following CLSI guidelines. In addition, metagenomic DNA was extracted and sequenced to assess microbial community composition and functional gene content, focusing on the identification of resistance genes and potential pathogens. Results: A total of 42 bacterial isolates were recovered, including genera with known pathogenic potential such as Aeromonas, Klebsiella, and Enterococcus. Antibiotic susceptibility tests revealed a high prevalence of multidrug-resistant strains. Metagenomic analysis identified the dominance of Bacillota and Bacteroidota, together with 56 antimicrobial-resistance gene (ARG) families and 38 virulence-factor families. Functional gene analysis indicated the presence of efflux-pump systems, β-lactamases, and mobile genetic elements, suggesting that untreated hospital effluents serve as potential sources of resistance and virulence determinants entering the environment. Paracetamol was detected in all samples, with an average concentration of 277.4 ± 10.7 µg/L; amoxicillin was not detected, likely due to its instability and rapid degradation in the wastewater matrix. Conclusions: These findings highlight the complex microbiological and chemical burden of untreated hospital wastewater and reinforce the need for continuous monitoring and improved treatment strategies to mitigate environmental dissemination of antibiotic resistance.

Wetlands are ecosystems that are essential to ecological balance and biodiversity; nevertheless, human activity is a constant threat to them. Excess nutrients are caused by intensive livestock and agricultural operations, pollution, and population growth, which in turn leads to uncontrolled microbiological development. This impairment in water quality can constitute a risk to animal, human, and environmental health. To thoroughly characterize the microbial communities, shotgun metagenomics was used to characterize the taxonomic and functional pattern of microorganisms that inhabit urban wetlands in the Los Lagos Region of Chile. The main objective was to identify microorganisms of veterinary relevance, assess their potential antibiotic resistance, and characterize the main virulence mechanism. As expected, a high diversity of microorganisms was identified, including bacteria described as animal or human pathogens, such as Pasteurella multocida, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Also, a diverse repertory of antimicrobial-resistant genes (ARGs) was detected in metagenomic assembled sequences and inside the sequence of mobile genetic elements, genes that confer mainly resistance to beta-lactams, consistent with the families of antibiotics most used in Chile. In addition, a diverse collection of virulence mechanisms was also identified. Given the significance of the relationship between environmental, animal, and human health—a concept known as One Health—there is a need to establish molecular surveillance programs that monitor the environmental biohazard elements using molecular tools. This work is the first report of the presence of these harmful biological elements in urban wetlands subjected to anthropogenic pressure, located in the south of Chile.

Wetlands are ecosystems that are essential to ecological balance and biodiversity, never-theless human activity is a constant threat to them. Excess nutrients are caused by inten-sive livestock and agricultural operations, pollution, and population growth, which in turn leads to uncontrolled microbiological development. This impairment in water quality can constitute a risk to animal, human, and environmental health. To thoroughly charac-terize the microbial communities, shotgun metagenomics was used to characterize the taxonomic and functional pattern of microorganisms that inhabit urban wetlands in the Los Lagos Region of Chile. The main objective was to identify microorganisms of veteri-nary relevance, assess their potential antibiotic resistance, and characterize the main vir-ulence mechanism. As expected, a high diversity of microorganisms was identified, in-cluding bacteria described as animal or human pathogens. Also, a diverse repertory of an-timicrobial-resistant genes (ARGs) was detected, which confers mainly resistance to be-ta-lactams, consistent with the families of antibiotics most used in Chile. Besides, a di-verse collection of virulence mechanisms was also identified. Given the significance of the relationship between environmental, animal, and human health—a concept known as One Health—there is a need to establish molecular surveillance programs. This work is the first report of the presence of these harmful biological elements in urban wetlands subjected to anthropogenic pressure, located in the south of Chile.