Insights into the complete genomes of carbapenem-resistant Acinetobacter baumannii harbouring bla (OXA-23, ) bla (OXA-420) and bla (NDM-1) genes using a hybrid-assembly approach

Carbapenem resistance in Acinetobacter baumannii is due to bla (OXA-23), which is endemic in India. Recently, the sporadic presence of bla (OXA-58) as well as the occurrence of dual carbapenemases were observed. The mobility as well as the dissemination of these resistance genes were mainly mediated by various mobile genetic elements. The present study was aimed at characterizing the genetic arrangement of bla (OXA-23, ) bla (NDM-1) and bla (OXA-58) identified in two complete genomes of carbapenem-resistant A. baumannii (CRAB). Complete genomes obtained using a hybrid-assembly approach revealed the accurate arrangement of Tn2006 with bla (OXA-23,) ISAba125 with bla (NDM) and ISAba3 with bla (OXA-58.) In addition, the association of IntI1 integrase with the bla (CARB-2) gene and several virulence factors required for type-IV pili assembly, motility and biofilm formation have been identified. The current study provided deeper insight into the complete characterization of insertion sequences and transposons associated with the carbapenem-resistant genes using short reads of IonTorrent PGM and long reads of MinIon in A. baumannii .