Whole-Genome Analysis of Two Copies of bla NDM-1 Gene Carrying Acinetobacter johnsonii Strain Acsw19 Isolated from Sichuan, China.

Abstract

PurposeTo characterize the genetic feature of the carbapenems resistant Acinetobacter johnsonii strain Acsw19 isolated from municipal sludge. This strain was found to carry two copies of blaNDM-1, cmlB1-like gene, and blaOXA-211-like gene along with other 8 antimicrobial resistance genes, 3 plasmids, 15 genomic islands and 8 prophages.MethodsA carbapenem-resistant Acinetobacter johnsonii strain Acsw19 isolated from municipal sludge was subjected to whole-genome sequencing (WGS) via the PacBio and Illumina MiSeq platforms. Thereafter, the characteristic was analyzed by a series of bioinformatics software.ResultsThe results showed that the genome of Acsw19 was consisted of a 3,433,749 bp circular chromosome and 3 circular plasmids, pAcsw19-1 (11,161 bp), pAcsw19-2 (351,885 bp) and pAcsw19-3 (38,391bp), respectively. Resistome analysis showed that Acsw19 carried 12 antimicrobial resistance genes, including 6 [cmlB1-like, blaNDM-1, blaOXA-58, aph (3ʹ)-VIa, msr(E) and mph(E)] in the plasmid pAcsw19-2 and 6 (blaOXA-211-like, blaNDM-1, aph(3")-Ib, aph(6)-Id, sul2, and floR) in the chromosome genome. Specifically, the cmlB1-like gene shared 86.33%, 71.7% and 71.9% similarities with the cmlB1, cmlA4 and cmlA8 gene, and the blaOXA-211-like gene shared 94.4%, 95.39% and 96.36% similarities with blaOXA-211, blaOXA-643 and blaOXA-652, at the nucleotide level, respectively. Phylogenetic analysis showed that the blaOXA-211-like gene and cmlB1-like gene had the closest evolutionary relationship with blaOXA-643 and cmlB1, respectively. These results indicated that the blaOXA-211-like and cmlB1-like genes identified in the current study should be the novel variant resistance genes.ConclusionCarrying of two copies of blaNDM-1, cmlB1-like, blaOXA-211-like and along with other 8 antimicrobial resistance genes, 3 plasmids, 15 genomic islands and 8 prophages Acinetobacter johnsonii strain might increase the possibility of spreading of resistance genes.