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Background An attenuated mutant (designated NY303) of Vibrio vulnificus, which causes serious wound infection and septicemia in humans, was isolated fortuitously from a clinical strain YJ016. This mutant was defective in cytotoxicity, migration on soft agar and virulence in the mouse. The purpose of this study was to map the mutation in this attenuated mutant and further explore how the gene thus identified is involved in virulence. Methods The whole genome sequence of mutant NY303 determined by next-generation sequencing was compared with that of strain YJ016 to map the mutations. By isolating and characterizing the specific gene-knockout mutants, the gene associated with the phenotype of mutant NY303 was identified. This gene encodes a global regulator, Lrp. A mutant, YH01, deficient in Lrp was isolated and examined in vitro, in vivo and ex vivo to find the affected virulence mechanisms. The target genes of Lrp were further identified by comparing the transcriptomes, which were determined by RNA-seq, of strain YJ016 and mutant YH01. The promoters bound by Lrp were identified by genome footprinting-sequencing, and those related with virulence were further examined by electrophoretic mobility shift assay. Results A mutation in lrp was shown to be associated with the reduced cytotoxicity, chemotaxis and virulence of mutant NY303. Mutant YH01 exhibited a phenotype resembling that of mutant NY303, and was defective in colonization in the mouse and growth in mouse serum, but not the antiphagocytosis ability. 596 and 95 genes were down- and up-regulated, respectively, in mutant YH01. Many of the genes involved in secretion of the MARTX cytotoxin, chemotaxis and iron-acquisition were down-regulated in mutant YH01. The lrp gene, which was shown to be negatively autoregulated, and 7 down-regulated virulence-associated genes were bound by Lrp in their promoters. A 14-bp consensus sequence, mkCrTTkwAyTsTG, putatively recognized by Lrp was identified in the promoters of these genes. Conclusions Lrp is a global regulator involved in regulation of cytotoxicity, chemotaxis and iron-acquisition in V. vulnificus. Down-regulation of many of the genes associated with these properties may be responsible, at least partly, for loss of virulence in mutant NY303. Electronic supplementary material The online version of this article (doi:10.1186/s12929-017-0361-9) contains supplementary material, which is available to authorized users.

The distribution of Lrp target genes in different functional categories. (DOCX 334Â kb)

Location of point mutation in lrp of V. vulnificus mutant NY303. (DOCX 72Â kb)

The mRNA levels of genes predicted to be involved in iron-acquisition and chemotaxis in the wild-type strain and Î lrp mutant. (DOCX 219Â kb)

Phagocytosis of various V. vulnificus strains by RAW 264.7 cells after mixed infection. (DOCX 55Â kb)

The mRNA levels of lrp in the wild-type strain incubated in various media. (DOCX 158Â kb)

Given the limited studies on emergency care management, this study aimed to explore the relationships of emergency department (ED) culture values to certain dimensions of ED physicians’ and nurses’ work satisfaction and intent to leave. Four hundred and forty-two emergency medical professionals completed the employee satisfaction questionnaire across 119 hospital-based EDs, which had culture value evaluations filed, were used as unit of analysis in this study. Adjusting the personal and employment backgrounds, and the surrounded EDs’ unit characteristics and environmental factors, multiple regression analyses revealed that clan and market cultures were related to emergency physicians’ work satisfaction and intent to leave. On the other hand, adhocracy, market and hierarchical cultures were related to emergency nurses’ work satisfaction. There do exist different patterns among various culture types on various work satisfaction dimensions and intent to leave of emergency physicians and nurses. The findings could offer hospital and ED leaders insights for changes or for building a better atmosphere to enhance the work life of emergency physicians and nurses.