Acinetobacter chinensis, a novel Acinetobacter species, carrying bla_NDM-1, recovered from hospital sewage

Two strains of the genus Acinetobacter, named WCHAc010005 and WCHAc010052, were isolated from hospital sewage at West China Hospital in Chengdu, China. The two strains were found to be resistant to carbapenems due to the presence of carbapenemase gene bla_NDM-1. Based on the comparative analysis of the rpoB sequence, the two strains formed a strongly supported and internally coherent cluster (intracluster identity of 98.7%), which was clearly separated from all known Acinetobacter species (≤ 83.4%). The two strains also formed a tight and distinct cluster based on the genuswide comparison of whole-cell mass fingerprints generated by MALDI-TOF mass spectrometry. In addition, the combination of their ability to assimilate malonate but not benzoate, and the inability to grow at 37°C could distinguish the two strains from all known Acinetobacter species. The two strains were subjected to whole genome sequencing using both short-read Illumina HiSeq2500 platform and the longread MinION sequencer. The average nucleotide identity and in silico DNA-DNA hybridization value between the genomes of WCHAc010005 and WCHAc010052 was 96.69% and 74.3% respectively, whereas those between the two genomes and the known Acinetobacter species were < 80% and < 30%, respectively. Therefore, the two strains represent a novel species of the genus Acinetobacter, for which the name Acinetobacter chinensis sp. nov. is proposed, and the type strain is WCHAc- 010005^T (= GDMCC 1.1232^T = KCTC 61813^T).