Genome sequence of a tigecycline-resistant Acinetobacter seifertii recovered in human bloodstream infection in China

Abstract

The phylogenetic characteristics of Acinetobacter seifertii clinical strain are not well-studied. Here, we reported one tigecycline-resistant ST1612PasteurA. seifertii isolated from bloodstream infections (BSI) in China. Antimicrobial susceptibility tests were conducted via broth microdilution. Whole-genome sequencing (WGS) was performed and annotation was conducted using rapid annotations subsystems technology (RAST) server. Multilocus sequence typing (MLST), Capsular polysaccharide (KL) and lipoolygosaccharide (OCL) were analyzed using PubMLST and Kaptive. Resistance genes, virulence factors and comparative genomics analysis were performed. Cloning, mutations of efflux pump related genes and expression level were further investigated. The draft genome sequence of A. seifertii ASTCM strain is made up of 109 contigs with a total length of 4,074,640 bp. Based on the RAST results, 3,923 genes that belonged to 310 subsystems were annotated. A. seifertii ASTCM was ST1612Pasteur with KL26 and OCL4, respectively. It was resistant to gentamicin and tigecycline. ASTCM harbored tet(39), sul2 and msr(E)-mph(E) and one amino acid mutation in Tet(39) (T175A) was further identified. Nevertheless, the signal mutation failed to contribute to susceptibility change of tigecycline. Of note, several amino acid substitutions were identified in AdeRS, AdeN, AdeL and Trm, which could lead to overexpression of adeB, adeG, and adeJ efflux pump genes and further possibly lead to tigecycline resistance. Phylogenetic analysis showed a huge diversity was observed among A. seifertii strains based on 27-52,193 SNPs difference. In summary, we reported a tigecycline-resistant ST1612PasteurA. seifertii in China. Early detection is recommended to prevent their further spread in the clinical setting.