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bioRxiv · 10.1101/678748

Integrative and conjugative elements, the neglected drivers of carbapenemase-encoding genes

Botelho, J.·Mourao, J.·Roberts, A. P.·Peixe, L. V.
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Abstract

Carbapenemases inactivate most {beta}-lactam antibiotics, including carbapenems and have been frequently reported among Enterobacteriaceae, Acinetobacter spp. and Pseudomonas spp. Traditionally, the horizontal gene transfer of carbapenemase encoding genes (CEGs) has been linked to plasmids. However, given that integrative and conjugative elements (ICEs) are possibly the most abundant conjugative elements among prokaryotes, we conducted an in-silico analysis to ascertain the likely role of ICEs in the spread of CEGs among all bacterial genomes (n=182,663). We detected 17,520 CEGs, of which 66 were located within putative ICEs among several bacterial species (including clinically-relevant bacteria as Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli). Most CEGs detected within ICEs belong to the IMP, NDM and SPM metallo-beta-lactamase families, and the serine beta-lactamase KPC and GES families. Different mechanisms were likely responsible for acquisition of these genes. The majority of CEG-bearing ICEs belong to the MPFG, MPFT and MPFF classes and often encode resistance to other antibiotics (e.g., aminoglycosides and fluoroquinolones). This study provides a snapshot of the different CEGs associated with ICEs among available bacterial genomes and sheds light on the underappreciated contribution of ICEs to the spread of carbapenem resistance globally. Author NotesAll supporting data has been provided within the article or through supplementary data files. Supplementary material is available with the online version of this article. Impact StatementCarbapenems are commonly used to treat severe infections in humans. Resistance is often mediated by carbapenemases. These enzymes degrade carbapenems and are frequently present in plasmids. Here, we demonstrate that common carbapenemase-encoding genes (CEGs) found in clinical isolates (e.g. blaKPC, blaGES, blaIMP, blaNDM, blaVIM) can also be located within integrative and conjugative elements (ICEs). CEG-bearing ICEs belong to three mating-pair formation families. These mobile elements may be particularly important in bacteria where plasmids do not seem to play a significant role in the spread of antibiotic resistance genes, as Pseudomonas spp. This study considerably expands the knowledge of the repertoire of CEGs-bearing ICEs among clinically-relevant bacterial pathogens, such as Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli. Data SummaryAll the bacterial genomes scanned in this study have been deposited previously in the National Center for Biotechnology Information genome database and are listed on the supplementary tables. The extracted 66 ICEs in fasta format and the outputs for the profile HMMs scanned on the 386 putative MGEs identified in this study are deposited on figshare at https://figshare.com/projects/_Comprehensive_genome_data_analysis_establishes_a_triple_whammy_of_carbapenemases_ICEs_and_multiple_clinically-relevant_bacteria/78369.

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Botelho, J., Mourao, J., Roberts, A. P., Peixe, L. V.. 2019-06-21. Integrative and conjugative elements, the neglected drivers of carbapenemase-encoding genes. https://doi.org/10.1101/678748

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