Insights into the complete genomes of carbapenem-resistant Acinetobacter baumannii harbouring blaOXA-23 blaOXA-420 and blaNDM-1 genes using a hybrid-assembly approach

摘要

Carbapenem resistance in Acinetobacter baumannii is due to blaOXA-23, which is endemic in India. Recently, the sporadic presence of blaOXA-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 blaOXA-23, blaNDM-1 and blaOXA-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 blaOXA-23, ISAba125 with blaNDM and ISAba3 with blaOXA-58. In addition, the association of IntI1 integrase with the blaCARB-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.