Aircraft Wastewater as a Sentinel for Transboundary Antimicrobial Resistance: An Integrated Genomic Approach.

Aircraft wastewater (AWW) provides a composite environmental matrix reflecting passengers from diverse geographic origins and may serve as a surveillance tool for AMR monitoring. To characterize microbial community composition, antimicrobial resistance genes (ARGs), virulence factor genes (VFGs), and genome-resolved features of AWW. Samples (N = 10) were collected from long-haul flights arriving in the UAE between October 2024 and February 2025. Shotgun metagenomic sequencing and high-throughput quantitative PCR (HT-qPCR) were performed. Metagenome-assembled genomes (MAGs) were reconstructed. Shotgun metagenomics identified 752 bacterial species dominated by gut-associated families, including Lachnospiraceae and Ruminococcaceae. A total of 345 ARGs were detected, with tetracycline resistance genes being most abundant. Regional variation in resistome composition was supported by permutational multivariate analysis of variance (PERMANOVA, p = 0.010), and principal coordinate analysis indicated separation by flight-origin region. MAG reconstruction recovered 1012 genomes, with 85.4% resolved to species level. MAG-based annotation identified 280 VFGs corresponding to 116 non-redundant virulence genes. HT-qPCR confirmed the widespread presence of key ARG classes and mobile genetic elements across samples, in keeping with metagenomic findings. AWW contains diverse microbial communities and AMR determinants. Genome-resolved analysis provided organism-level context for resistome and virulome characterization, confirming AWW as an environmental matrix for monitoring transboundary AMR dynamics.