Gut microbiome and resistome changes during the first wave of the COVID-19 pandemic in comparison with pre-pandemic travel-related changes

COVID-19-associated measures had a greater impact on gut microbiota, antibiotic resistance genes and biocide resistance genes than did pre-pandemic international travel. During the COVID-19 pandemic, Actinobacteria richness decreased, whereas genes conferring resistance to beta-lactam, polystyrene and phthalate increased. Such alterations may affect both colonization resistance and acquisition and spread of antimicrobial resistance in future travels.