Jones-Dias, DanielaCaniça, ManuelaManageiro, Vera2017-03-062017-03-062016In: Shelton C. (ed). Superbugs - Clostridium difficile and Klebsiella pneumoniae: Recognition, Prevention and Treatment. Hauppauge NY: Nova Science Publishers, 2016. pp. 57-72978-1-63484-412-3http://hdl.handle.net/10400.18/4484Carbapenem-resistant Klebsiella pneumoniae have emerged as a class of pathogens that pose a significant threat to patients admitted to healthcare facilities. This phenotype is mostly due to the production of carbapenemases, which constitute the group of β-lactamases capable of hydrolysing all β-lactam antibiotics, including carbapenems. However, the successful worldwide dissemination of carbapenem resistant K. pneumoniae has been linked to the emergence of a specific type of carbapenemase: KPC (K. pneumoniae carbapenemase). Although this carbapenemase has been identified in several sequence-types (STs), the pandemic seems to be mainly driven by the spread of KPC-producing K. pneumoniae from ST258. Apart from the triumph of the clonal spread, there is a considerable variability in the number of mobile genetic elements that KPC-producing K. pneumoniae might harbour, and that contribute to the mobilization and transference of the KPC-encoding gene (blaKPC). This transmission can be mediated by different molecular mechanisms that include the mobilization of minor genetic elements and the horizontal transfer of different conjugative plasmids. Tn4401 transposon is highly involved in the horizontal dissemination of blaKPC. This transposon can even assume different isoforms that, in turn, may become associated with multiple blaKPC-bearing plasmids. Although many plasmids have been linked to the dissemination of blaKPC gene, the incompatibility groups enclosing Tn4401 seem to be predominant. In K. pneumoniae, other carbapenem resistance determinants have been identified throughout the years but none has disseminated to the extent of KPC. Its spread and success seems to be multifactorial with virulence factors, antibiotic resistance determinants and mobile genetic elements playing major roles. Only the early detection of these factors may ease their establishment worldwide and prevent their emergence in non endemic countries.engAntibiotic ResistanceCarbapenemaseKlebsiella PneumoniaeInfectious DiseasesResistência aos Antimicrobianosbook part