Abstract
OBJECTIVE: The aim of this study was to investigate the genomic features of carbapenem-resistant Citrobacter spp. carrying bla(NDM-4) on a novel IncFII-116 plasmid. METHODS: Carbapenem-resistant Citrobacter spp. isolates were collected from diarrheal inpatients. Antibiotic susceptibility testing was routinely performed. Whole-genome sequencing and bioinformatic analyses were conducted on the isolates with bla(NDM-4) gene. RESULTS: Whole- genome sequencing was performed on the two C. amalonaticus isolates carrying bla(NDM-4). Whole-genome analysis revealed that pL5091_bla(NDM-4) and pL5094_bla(NDM-4)belong to a new type of plasmid (IncFII-116) with lengths of 87124 bp and 87952 bp in two C. amalonaticus, respectively. Moreover, bla(NDM-4) was encoded in the trpF-ble-bla(NDM-4)-IS15 cassette array. CONCLUSION: We identified a novel IncFII-116 plasmid carrying bla(NDM-4) in C. amalonaticus for the first time, raising concerns about the emergence of carbapenem-resistant Citrobacter spp.