Carbapenemases on the move: it’s good to be on ICE
The evolution and spread of antibiotic resistance is often mediated by mobile geneticelements. Integrative and conjugative elements (ICEs) are the most abundant conjugativeelements among prokaryotes. However, the contribution of ICEs to horizontal gene transferof antibiotic resistance has been largely unexplored. Here we report that ICEs belonging tomating-pair formation (MPF) classes G and T are highly prevalent among the opportunisticpathogen Pseudomonas aeruginosa, contributing to the spread of carbapenemase-encodinggenes (CEGs). Most CEGs of the MPFG class were encoded within class I integrons, which co-harbour genes conferring resistance to other antibiotics. The majority of the integrons werelocated within Tn3-like and composite transposons. A conserved attachment site could bepredicted for the MPFGclass ICEs. MPFTclass ICEs carried the CEGs within compositetransposons which were not associated with integrons. The data presented here provides aglobal snapshot of the different CEG-harbouring ICEs and sheds light on the underappreciatedcontribution of these elements for the evolution and dissemination of antibiotic resistanceon P. aeruginosa.