Monitoring Cross-Border Dissemination of Antimicrobial Resistance (AMR) via Air Travel to Saudi Arabia: Formulation of Monitoring Strategies to Mitigate AMR Concerns

Antimicrobial resistance (AMR) is a global health challenge, and its dissemination can be accelerated by international air travel. Aircraft sewage, aggregating microbial material from global travelers, offers a unique surveillance opportunity for AMR at international entry points. However, specific AMR elements detected in aircraft sewage and how their relative abundance and transcriptional activity may be associated with flight characteristics such as flight duration or departure country remain unclear. This study analyzed 130 sewage samples from international flights arriving in Saudi Arabia across 27 countries. Metagenomic analyses revealed distinct AMR profiles in aircraft sewage compared to local municipal sewage, including elevated relative abundances of <i>Enterococcus faecium</i> and <i>Staphylococcus aureus</i>. Aircraft sewage harbored 51 antibiotic resistance genes (ARGs) that were not detected in local municipal sewage, predominantly carbapenem-resistant genes (e.g., <i>bla</i>_NDM, <i>bla</i>_VIM). Additionally, geographical origin of flights shaped AMR composition with lower ARG diversity observed from African-origin flights, whereas Asian and American flights exhibited enriched ARG profiles. Flight length affected AMR expression with long-haul flights (>3500 km) associated with elevated transcription levels. These findings demonstrated how international air travel facilitates the dissemination of AMR across regions and provided actionable insights to devise aircraft sewage surveillance strategies.