Enterobacteriaceae co-producing NDM-and OXA-48-type carbapenemases were encountered in higher frequency in the United Arab Emirates (UAE) than in the neighboring countries in our earlier study. The aim of this investigation was to characterize the seven double carbapenemase producer Klebsiella pneumoniae found in the region to assess factors contributing to their emergence. Three K. pneumoniae ST14 isolated in the UAE harboring bla NDM-1 on IncHI1b and bla OXA-232 on IncColE plasmids were

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... ly related. Furthermore, two K. pneumoniae from the UAE, ABC106 and ABC137 belonged to ST307 and ST1318, respectively. ABC106 carried bla NDM-1 on IncHI1b, and bla OXA-162 on IncL/M plasmids, whereas ABC137 possessed bla NDM-1 on IncX3 and bla OXA-48 on IncL/M plasmids. The double carbapenemase-producing K. pneumoniae from Oman (OMABC109) and Saudi Arabia (SA54) belonged to ST11 and ST152, respectively. OMABC109 harbored bla NDM-1 on an IncHI1b plasmid highly similar to the NDM-plasmid of ABC106 and carried a chromosomally coded bla OXA-181 located on Tn2013. SA54 possessed a bla NDM-1 on an IncFIb/FII plasmid and a bla OXA-48 on an IncL/M plasmid. Based on these findings, clonal spread and horizontal transfer of carbapenemase genes located on transposons or self-transmissible plasmids contributed equally to the emergence of double carbapenemase-producing Enterobacteriaceae in the region.