Contribution of horizontal gene transfer to the emergence of VIM-4 carbapenemase producer Enterobacteriaceae in Kuwait Ágnes Sonnevend,1 Nour Yahfoufi,1,2 Akela Ghazawi,1 Wafaa Jamal,3 Vincent Rotimi,3 Tibor Pál1 1Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, UAE; 2Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada; 3Department of Microbiology, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait Abstract: Carbapenem-resistant Enterobacteriaceae encountered in countries of the Arabian Peninsula usually produce OXA-48-like and New Delhi metallo-beta-lactamases (NDM) carbapenemases. However, a temporary increase in VIM-4-producing, clonally unrelated Enterobacteriaceae strains was described earlier in a Kuwaiti hospital. We investigated the genetic support of blaVIM-4 in six Klebsiella pneumoniae strains, one Escherichia coli, and one Enterobacter cloacae strain and compared it to that of VIM-4-producing isolates from other countries of the region. Five K. pneumoniae strains and the E. coli strain from Kuwait carried an ~165 kb IncA/C-type plasmid indistinguishable by restriction fragment length polymorphism. The complete sequence of one of them (pKKp4-VIM) was established. pKKp4-VIM exhibited extensive similarities to episomes pKP-Gr642 carrying blaVIM-19 encountered in Greece and to the partially sequenced pCC416 harboring blaVIM-4 detected in Italy. In other countries of the region, the only similar plasmid was the one detected in the isolate from the UAE. In all Kuwaiti strains, irrespective of the species and their VIM plasmids, the blaVIM-4 gene was located within the same integron structure (In416), different from those of other countries of the region. Our data show that the spread of this IncA/C plasmid and particularly that of the In416 integron caused a considerable, albeit temporary, increase in the rate of mostly clonally unrelated VIM-producing Enterobacteriaceae strains of multiple species. Monitoring of such events is of high importance as the interference with the spread of mobile genetic elements may represent a formidable challenge to infection control. Keywords: Enterobacteriaceae, VIM carbapenemase, horizontal gene transfer, multidrug resistance, Middle East