Genome contamination may lead to an overestimation of horizontal gene transfer inferences

Horizontal gene transfer (HGT) through mobile genetic elements (MGEs) is the main driver of the dissemination of antibiotic resistance genes (ARGs) between bacterial species 1 . In 2021, Ellabaan et al. proposed an in silico approach to predict new bacterial hosts for currently known ARGs, which could help in defining ARG-specific risk assessment of future dissemination 2 . They used publicly available genomic data to confirm their predictions, but 30 of their 34 proposed transfer events were incorrectly assigned due to contamination in the sequence data, raising major concerns about the reliability of their results.