An outbreak of a nosocomial NDM-1-producing Klebsiella pneumoniae ST147 at a teaching hospital in mainland China.

A total of 1,870 nonduplicate clinical Enterobacteriaceae from 13 teaching hospitals located in 11 provinces of mainland China from 2011 to 2012 were screened for the presence of the blaNDM gene. The high-throughput MiSeq sequencing method and comparative genomics were used to analyze the genetic environment of blaNDM among these isolates. Three blaNDM-1-carrying Klebsiella pneumoniae (0.16%, 3/1,870), isolated from a teaching hospital in Xi'an, exhibited high levels of resistance to all β-lactams, but remained susceptible to amikacin, tigecycline, and polymyxin B. These three isolates, belonging to ST147, presented an identical pulsed-field gel electrophoresis pattern. The IncX3 plasmid, pNDM-SX04 (KC876051) showed 99% identity with plasmid pNDM-HN380 (JX104760). Comparative analysis of the genetic environment of blaNDM-1 with previously published plasmids revealed the same 7,830-bp basic mobile element, which may have been derived from Acinetobacter spp. Partial ISAba125, ISAba125 promoter, blaNDM-1, and bleMBL could serve as the minimal mobile vehicle facilitating horizontal transfer of the blaNDM-1 gene. To our knowledge, this is the first report of an outbreak of blaNDM-1-carrying ST147 K. pneumoniae. Although the prevalence spread by the blaNDM-1 gene prevalence is at a low frequency in mainland China, a dynamic national surveillance of this gene is needed due to its potential transferability.