Abstract:

Objective

To interpret the phenotype， genotype and evolutionary model of Vibrio vulnificus （V. vulnificus） based on acute sepsis cases， and to improve the diagnosis and treatment of emerging zoonoses.

Methods

A 48-hour blood culture of a patient （male， 71 years old） with sepsis secondary to acute gastroenteritis admitted to the emergency department of Renji Hospital， Shanghai Jiao Tong University School of Medicine on June 21st， 2016 was isolated， the strain was identified by MALDI-TOF-MS， biochemical and drug resistance phenotype， and whole genome sequencing （WGS） was used to predict multi-site sequence type （MLST）， annotation of drug resistance genes， mobile elements and virulence factors. The phylogenetic tree of gene cluster （C1-C4） analysis was constructed based on single nucleotide polymorphism （SNPs）. The characteristics of V. vulnificus cases in different regions of China （including Hong Kong and Taiwan） from 2012 to 2023 were analyzed by literature， then characteristics of V. vulnificus cases in China， the United States and South Korea in different periods were compared.

Results

The patient had a history of seafood consumption and chronic renal insufficiency， and was clinically diagnosed with sepsis and acute gastroenteritis. The patient was cured through anti-infection and symptomatic treatment with levofloxacin and cefepime for 14 days. The isolated strain was identified as V. vulnificus biotype 1 by biochemical and MALDI-TOF-MS. It was sensitive to all drugs except polymyxin. WGS predicted a new sequence type ST14514， and the phylogenetic tree suggested cluster type 1 （clinical type C1）， carrying hypervirulence genes wza， vvhA， rtxA， vvp and luxS. The top five provinces among 15 provinces which reported 148 cases with V. vulnificus infection in China were Guangdong， Zhejiang， Fujian， Shanghai and Jiangsu， and the ratio of male to female was about 4∶1. Total of 132 cases and 16 cases were confirmed by culture and mNGS， respectively. Fifty-five cases （37.16%） died，and 99 cases （66.89%） were exposed to seawater， fish and shrimp injuries， or eating seafood. The mortality of V. vulnificus infection in China mainland was lower than that in the United States and South Korea. The main route of infection was direct or indirect contact with seawater （sea-products）. The high mortality was characterized by male liver disease （hepatitis， alcoholic liver disease， cirrhosis）.

Conclusions

ST14514 is a new C1 clinical strain type， with high toxicity and low resistance. Sepsis patients secondary to gastroenteritis caused by V. vulnificus are often occult， rare， and Propaganda and education of V. vulnificus diagnosis and ecotype and exposure risk to professional organizations and the mass should be strengthened， in order to enhance the capacity of treatment and reduce the mortality.

Key words: Vibrio vulnificus, Emerging, Virulence factor, Genomics, Cluster analysis, Mortality