In the first part of our work, following two outbreaks that involved K. pneumoniae producing carbapenemases, we defined a clear strategy that allowed us to control and stop the spread of those strains. Similar measures have been applied successfully in other hospitals in France, Israel and the United States. These two outbreaks, linked to the spread of epidemic clones, led us to study the prevalence of virulence factors among an international collection of multidrug-resistant K. pneumoniae strains. We could establish a link between resistance and virulence with, especially a high prevalence (42%) of a pathogenicity island bearing the yersiniabactin, Ybts, which plays an essential role in the expression of hyper-virulent phenotype of Yersinia sp. In the second part of our work, we showed that strains of K. pneumoniae producing CTX-M-15 type ESBL, are associated with plasmids belonging to incompatibility group IncF whereas plasmids carrying blaSHV genes and carbapenemases, are less well characterized by the PCR method. These results lead to the sequencing of plasmids. We report the complete nucleotide sequence of the first IncX plasmid carrying a blaKPC-2 gene from Klebsiella. It consists of the backbone of the IncX plasmid and carries a region encoding both KPC-2 and SHV-12. The transposon Tn4401 is inserted in a part encoding the blaSHV-12
