Draft Genome Sequence of Acinetobacter johnsonii MB44, Exhibiting Nematicidal Activity against Caenorhabditis elegans

Complete genetic characterization of carbapenem-resistant Acinetobacter johnsonii, co-producing NDM-1, OXA-58, and PER-1 in a patient source

The emergence of carbapenemase-producing Acinetobacter spp. has been widely reported and become a global threat. However, carbapenem-resistant A. johnsonii strains are relatively rare and without comprehensive genetic structure analysis, especially for isolates collected from human specimen. Here, one A. johnsonii AYTCM strain, co-producing NDM-1, OXA-58, and PER-1 enzymes, was isolated from sputum in China in 2018. Antimicrobial susceptibility testing showed that it was resistant to meropenem, imipenem, ceftazidime, ciprofloxacin, and cefoperazone/sulbactam. Whole-genome sequencing and bioinformatic analysis revealed that it possessed 11 plasmids. bla OXA-58 and bla PER-1 genes were located in the pAYTCM-1 plasmid. Especially, a complex class 1 integron consisted of a 5' conserved segment (5' CS) and 3' CS, which was found to carry sul1, arr-3, qnrVC6, and bla PER-1 cassettes. Moreover, the bla NDM-1 gene was located in 41,087 conjugative plasmids and was quite stable even after 70 passages under antibiotics-free conditions. In addition, six prophage regions were identified. Tracking of closely related plasmids in the public database showed that pAYTCM-1 was similar to pXBB1-9, pOXA23_010062, pOXA58_010030, and pAcsw19-2 plasmids, which were collected from the strains of sewage in China. Concerning the pAYTCM-3 plasmids, results showed that strains were collected from different sources and their hosts were isolated from various countries, such as China, USA, Japan, Brazil, and Mexico, suggesting that a wide spread occurred all over the world. In conclusion, early surveillance is warranted to avoid the extensive spread of this high-risk clone in the healthcare setting.

Complete Genome Sequence of a Rare Pigment-Producing Strain of Acinetobacter johnsonii, Isolated from the Bile of a Patient in Hangzhou, China

Here, we report the complete genome sequence of a rare pigment-producing strain of Acinetobacter johnsonii. The genome consists of a 3,360,823-bp circular chromosome (G+C content, 41.56%) and an 8,887-bp plasmid (G+C content, 33.71%). It possesses 3,038 coding gene sequences, 19 rRNA genes, 87 tRNA genes, and 4 noncoding RNA (ncRNA) genes.

Genome-sequence analysis of Acinetobacter johnsonii MB44 reveals potential nematode-virulent factors

Acinetobacter johnsonii is generally recognized as a nonpathogenic bacterium although it is often found in hospital environments. However, a newly identified isolate of this species from a frost-plant-tissue sample, namely, A. johnsonii MB44, showed significant nematicidal activity against the model organism Caenorhabditis elegans. To expand our understanding of this bacterial species, we generated a draft genome sequence of MB44 and analyzed its genomic features related to nematicidal attributes. The 3.36 Mb long genome contains 3636 predicted protein-coding genes and 95 RNA genes (including 14 rRNA genes), with a G + C content of 41.37 %. Genomic analysis of the prediction of nematicidal proteins using the software MP3 revealed a total of 108 potential virulence proteins. Some of these proteins were homologous to the known virulent proteins identified from Acinetobacter baumannii, a pathogenic species of the genus Acinetobacter. These virulent proteins included the outer membrane protein A, the phospholipase D, and penicillin-binding protein 7/8. Moreover, one siderophore biosynthesis gene cluster and one capsular polysaccharide gene cluster, which were predicted to be important virulence factors for C. elegans, were identified in the MB44 genome. The current study demonstrated that A. johnsonii MB44, with its nematicidal activity, could be an opportunistic pathogen to animals.