Integrative and conjugative elements of <i>Pasteurella multocida</i>: Prevalence and signatures in population evolution

<i>Pasteurella multocida</i> (<i>P. multocida</i>) is a bacterial pathogen responsible for a range of infections in humans and various animal hosts, causing significant economic losses in farming. Integrative and conjugative elements (ICEs) are important horizontal gene transfer elements, potentially enabling host bacteria to enhance adaptability by acquiring multiple functional genes. However, the understanding of ICEs in <i>P. multocida</i> and their impact on the transmission of this pathogen remains limited. In this study, 42 poultry-sourced <i>P. multocida</i> genomes obtained by high-throughput sequencing together with 393 publicly available <i>P. multocida</i> genomes were used to analyse the horizontal transfer of ICEs. Eighty-two ICEs were identified in <i>P. multocida</i>, including SXT/R391 and Tn916 subtypes, as well as three subtypes of ICE<i>Hin</i>1056 family, with the latter being widely prevalent in <i>P. multocida</i> and carrying multiple resistance genes. The correlations between insertion sequences and resistant genes in ICEs were also identified, and some ICEs introduced the carbapenem gene <i>bla</i>_OXA-2 and the bleomycin gene <i>bleO</i> to <i>P. multocida</i>. Phylogenetic and collinearity analyses of these bioinformatics found that ICEs in <i>P. multocida</i> were transmitted vertically and horizontally and have evolved with host specialization. These findings provide insight into the transmission and evolution mode of ICEs in <i>P. multocida</i> and highlight the importance of understanding these elements for controlling the spread of antibiotic resistance.