Emergence of Phytobacter diazotrophicus carrying an IncA/C2 plasmid harboring blaNDM-1 in Tokyo, Japan

Hiroaki Kubota, Tomohiro Nakayama, Tsukasa Ariyoshi, Satomi Uehara, Yumi Uchitani, Sachio Tsuchida, Hiroyuki Nishiyama, Ichiro Morioka, Tsugumichi Koshinaga, Akiko Kusabuka, Naoki Nakatsubo, Takuya Yamagishi, Yuri Tabuchi, Rumi Okuno, Kai Kobayashi, Morika Mitobe, Keiko Yokoyama, Takayuki Shinkai, Jun Suzuki, Kenji Sadamasu

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1 Citation (Scopus)


Phytobacter diazotrophicus is an Enterobacterales species that was originally identifiedas a plant growth-promoting, Gram-negative bacterium. Recently, this species has been recognized as relevant to opportunistic human and nosocomial infections in clinical settings. Its frequent misidentificationas other Enterobacterales species from clinical examination occasionally causes a delay in the identificationof nosocomial outbreaks. Here, we report the emergence of New Delhi metallo-β-lactamase (NDM)-producing P. diazotrophicus isolated from hospitalized pediatric patients and hospital environments in Tokyo, Japan. In our case, these isolates were found during an investigation of carbapenem-resistant Enterobacterales in relation to nosocomial infections. Whole-genome sequencing is useful for overcoming the difficultyof species identification.Furthermore, we found that blaNDM-1 was carried by an IncA/C2 plasmid (approximately 170 kbp), which was transferrable from the clinical isolates to the recipient strain Escherichia coli J53. Our study demonstrated that P. diazotrophicus behaves as a carrier of blaNDM-harboring plasmids, potentially disseminating resistance to carbapenems among Enterobacterales.

Original languageEnglish
Issue number4
Publication statusPublished - Aug 2023


  • Enterobacteriaceae
  • antibiotic resistance
  • genome analysis
  • genotypic identification
  • molecular epidemiology
  • plasmid-mediated resistance


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