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

ABSTRACT: Objectives: The phylogenetic characteristics of Acinetobacter seifertii clinical strain are not well-studied. Here, we reported one tigecycline-resistant ST1612Pasteur A. seifertii isolated from bloodstream infections (BSI) in China. Methods: 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 analysed 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. Results: 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, 3923 genes that belonged to 310 subsystems were annotated. Acinetobacter seifertii ASTCM was ST1612Pasteur with KL26 and OCL4, respectively. It was resistant to gentamicin and tigecycline. ASTCM harboured 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 that a huge diversity was observed among A. seifertii strains based on 27–52,193 SNPs difference. Conclusion: In summary, we reported a tigecycline-resistant ST1612Pasteur A. seifertii in China. Early detection is recommended to prevent their further spread in clinical settings

Mineralogy and geochemistry of the Proterozoic Wafangzi ferromanganese deposit, China

In the Proterozoic Wafangzi deposit, China, sedimentary manganite ores are interstratified with red shale and silty limestone, whereas sedimentary rhodochrosite ores are interbedded with organic-rich black shale. Lateral change in mineralogy of the ores accompanying lateral changes in the host rocks demonstrates a classic example of facies variation in a "zoned" deposit. The manganite ores show a distinct Ce depletion reflecting a hydrothermal contribution in the seawater from which they precipitated. Absence of volcanics in the sequence suggests that the source of the hydrothermal input should be remote. It is likely that manganite precipitated directly from seawater in these deposits above the redox interface, whereas rhodochrosite was possibly early diagenetic formed in an anoxic environment. Manganite has been converted to braunite through a deoxidation-dehydration reaction during late diagenesis. Both types of ores have been thermally metamorphosed at the contact with igneous intrusions. Four distinct mineral assemblages have been identified in the thermally metamorphosed ores which were produced as a result of variations in bulk compositions (including volatiles) of the premetamorphic ores. In the final stage, the ores have been affected by supergene processes to give rise to pyrolusite-vernadite assemblages in the weathering zone