Frontiers in Microbiology (Dec 2015)

Klebsiella pneumoniae: development of carbapenem resistance due to acquisition of blaNDM-1 during antimicrobial therapy in twin infants with pneumonia

  • Junying eZhu,
  • Baixing eDing,
  • Xiaogang eXu,
  • Demei eZhu,
  • fan eYang,
  • Hong eZhang,
  • Fupin eHu

DOI
https://doi.org/10.3389/fmicb.2015.01399
Journal volume & issue
Vol. 6

Abstract

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Objectives: To identify the mechanism of in vivo development of carbapenem resistance in Klebsiella pneumoniae.Methods: Seven sequential isolates of K. pneumoniae were obtained from twin infants with pneumonia. Antimicrobial susceptibility testing was performed by agar dilution. Carbapenemases including KPC and ML were initially screened using phenotypic methods, and carbapenemase-encoding genes were identified by PCR and amplicon sequencing. Plasmids of all clinical isolates and the conjugants of resistant isolates were estimated by S1 pulsed-field gel electrophoresis (PFGE). Molecular typing were conducted by PFGE of XbaI-digested genomic DNA and multilocus sequence typing (MLST). Results: For old brother, the first and third isolates were susceptible to meropenem, whereas the second and fourth isolates were resistant (MICs 16 mg/L). The first and second isolates from the young brother were susceptible to meropenem whereas the third isolate was resistant. All the resistant isolates produced NDM-1 metallo--lactamase. PFGE of XbaI-digested DNA revealed identical patterns for all the 7 isolates. All the isolates had the same sequence type named sequence type 37 (ST37). Conclusions: To our knowledge, this is the first documented case of development of carbapenem resistance in vivo mediated by NDM-1 metallo-b-lactamase in K. pneumoniae during treatment of pneumonia with meropenem.

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