RESEARCH ARTICLE Open Access

Full list of author information is available at the end of the articleBackground Carbapenems are recommended antibiotics for the treat-ment of nearly all Enterobacteriaceae in the past but now becoming increasingly ineffective to extended-spectrum β-lactamase (ESBL)-producing multidrug resistant bacter-ial infections [1,2]. Metallo-β-lactamases (MBLs) that hydrolyze all β-lactams including carbapenems are found with increasing frequency among the Enterobacteriaceae and non-Enterobacteriaceae from human, animals and the environment [3,4], limiting the effectiveness of antimicro-bial therapy. The plasmid-located carbapenem resistance gene blaNDM-1 was first detected in Klebsiella pneumoniae [5]. The gene, often flanked by mobile genetic elements, is now one of the most widespread carbapenemases genes and has been detected worldwide in multiple Gram-negative bacterial species including Acinetobacter spp., Escherichia coli and Klebsiella spp. [6]. Globalization and international travel accelerates the rapid dissemination o