NDM-1-producing Klebsiella pneumoniae isolated in the Sultanate of Oman

To analyse the mechanisms responsible for multidrug resistance in two carbapenem-resistant Klebsiella pneumoniae isolates recovered from patients hospitalized in Oman. PCR and sequencing were used to search for beta-lactamase and 16S RNA methylase genes. Multilocus sequence typing was used to determine the sequence type (ST) of each isolate. Clonal relationships were evaluated by PFGE. Both isolates carried the bla(NDM-1) carbapenemase gene. Isolate 601 was recovered from a patient who was transferred from India, whereas isolate 419 was from an Omani patient who had not travelled abroad. The two isolates were clonally unrelated, and belonged to ST14 (isolate 601) and ST340 (isolate 419). In addition to NDM-1, the ST14 isolate expressed beta-lactamases CTX-M-15, SHV-28, OXA-1, OXA-9 and TEM-1, and the aminoglycoside resistance methylase ArmA. The ST340 isolate expressed beta-lactamases SHV-11, OXA-1 and ArmA. In both isolates, the bla(NDM-1) gene was located on plasmids that were of similar size (170 kb), but of different incompatibility groups. This is the first description of NDM-1 producers in the Arabian peninsula and in the Middle East.