Since New Delhi metallo-β-lactamase-1 (NDM-1) was first detected , several variants have been further identified that differ by one or two amino acid substitutions. In 2014, a novel NDM-9 metallo-β-lactamase was first identified from a sequence type 107 (ST107) Klebsiella pneumoniae strain . Like the other NDM variants, NDM-9 confers high levels of resistance and compromises the effectiveness of most antibiotics, including carbapenems [2–4]. Although polymyxin B and colistin (polymyxin E) offer limited treatment options for multidrug-resistant (MDR) organisms carrying NDM-9, the emergence of the plasmid-mediated colistin resistance gene mcr-1 (for mobilised colistin resistance gene) conferring resistance to colistin (polymyxin E) may attenuate the utility of colistin.
International Journal of Antimicrobial Agents, v.49, n.4, pp.517-518