Genomic Characterization of a Carbapenem-Resistant Acinetobacter pittii Strain Harboring Chromosome-Borne blaNDM-1 from China

New Delhi metallo-beta-lactamase (NDM)-producing <i>Acinetobacter</i> spp. have been reported worldwide and become a global threat to clinics. This study aimed to characterize the genomic features of the carbapenem-resistant <i>Acinetobacter pittii</i> strain AP8900 harboring chromosome-borne <i>bla</i>_NDM-1. The genome of strain AP8900 was fully sequenced using Illumina and PacBio platforms. Genome analyses revealed that the chromosome-borne <i>bla</i>_NDM-1 of strain AP8900 was located on the Tn<i>125</i> bracketed by two copies of IS<i>Aba125</i> in the same orientation. So far, only five strains of <i>A. pittii</i> with complete genomes harboring chromosome-borne <i>bla</i>_NDM-1 were found (four from China and one from the USA), all carrying nearly identical Tn<i>125</i> carried by the strain AP8900. Furthermore, the Tn<i>125</i> of strain AP8900 in this study was also distributed in other species, mainly <i>Acinetobacter</i> spp. Notably, the Tn<i>125</i> carried by AP8900 also found in <i>Proteus mirabilis</i>, <i>Klebsiella pneumoniae</i>, and <i>Morganella morganii</i>. In addition, two antibiotic resistance plasmids were found in strain AP8900, and the configuration "<i>sul2</i>- <i>glmM</i>" was found on both pAP8900-1 (<i>ISAba1</i>-<i>sul2</i>-<i>glmM</i>-IS<i>Vsa3</i>-IS<i>1006</i>) and pAP8900-2 (∆IS<i>Aba2</i>-<i>sul2</i>-<i>glmM</i>-IS<i>17</i>). This study delivers comprehensive insights into the characteristics and diversity of chromosome-borne <i>bla</i>_NDM-1 in <i>A. pittii</i>. The complete genome of <i>A. pittii</i> AP8900 strain from southern China provides important data for the analysis of antimicrobial resistance in this region.