ABSTRACT
We report the first confirmed cases of NDM-1-producing Klebsiella pneumoniae infections in two hospitals in Bulgaria. The isolates were diverse in terms of plasmid and co-resistance gene content. K. pneumoniae PR2682, causing sepsis in patient with polytrauma due to traffic accident, harbored blaNDM-1,blaCMY-4, blaCTX-M-15, blaSHV-1, blaTEM-1b, qnrB, and aac(6')-Ib. blaNDM-1 was transferable by conjugation and located on an IncA/C plasmid of 176-kb, which also carried blaCMY-4, blaCTX-M-15, blaTEM-1b, and qnrB. K. pneumoniae PR2830, causing urinary tract infection in prostate cancer patient, harbored blaNDM-1,blaSHV-1, blaTEM-1, and aac(6')-Ib. blaNDM-1 was carried on an 86-kb IncA/C plasmid transferable by conjugation together with blaTEM-1, and aac(6')-Ib. Multilocus sequence typing indicated that the two isolates belonged to sequence type ST11. The emergence of NDM-1-producing K. pneumoniae indicates that blaNDM-1-mediated resistance is already disseminated among Enterobacteriaceae in Bulgaria. Our results further confirm the role of the Balkans as a secondary reservoir where NDM-encoding genes originate.