Isolation of Aureimonas altamirensis from whole blood and whole genome sequence analysis / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To understand the biological characteristics, identification methods, genome structure and clinical significance of a rare strain of Aureimonas altamirensis isolated from clinical blood sample. Methods:The culture and biochemical characteristics of a strain isolated from blood culture were observed. The routine biochemical identification methods, MALDI-TOF mass spectrometer and 16S rRNA gene sequencing were used to identify the isolate. A phylogenetic tree based on the 16S rRNA gene sequences of the isolate and related strains was constructed. The genome of the isolated strain was sequenced and assembled, and gene prediction and functional annotation were made using related software. Phylogenetic analysis based on 31 house-keeping genes and genome-wide average nucleotide identity (ANI) analysis were conducted between the isolate and other Aureimonas sp. strains.Results:The isolated bacteria were gram-negative bacillus positive for catalase, urease and oxidase. It grew slowly on blood plate and could not be reliably identified by automatic bacterial biochemical identification systems or MALDI-TOF mass spectrometry. Results of the 16S rRNA gene sequencing and phylogenetic tree showed that the 16S rRNA gene sequence of the isolated strain was highly homologous to the strains of Aureimonas altamirensis NML070722 and IARI-ABL-26 (GenBank accession number EU442518.1 and KC581669.1) in GenBank, and the gene sequence similarity was 99.93%. The total genome (National Microbiology Data Center genome accession number NMDC60043566) length was 4 332 458 bp and GC content was 65.14%. There were 4 088 protein-coding genes and functional gene annotation showed that functional genes were mainly enriched in protein, amino acid, carbohydrate transport and metabolic functional regions. Pathogenic gene analysis predicted two high reliable virulence factor genes, but no drug resistance genes. House-keeping gene phylogenetic tree analysis showed that this strain was highly homologous to Aureimonas altamirensis strains of DSM21988 and C2P003 (GenBank accession number GCF 001463885.1 and GCF 000800175.1), but ANI analysis showed that its genome was significantly different from those of the two strains. Conclusions:A rare strain of Aureimonas altamirensis was isolated from clinical specimen in China. As the biological and genomic characteristics of Aureimonas altamirensis had not been fully recognized, it was difficult to be correctly identified by conventional methods. The pathogenicity of Aureimonas altamirensis to immunocompromised patients and the significance of isolation in clinical specimens might need more case studies.