Etiologic characteristics analysis of a case of food poisoning caused by O10∶K4 Vibrio parahaemolyticus
Objective To analyze the etiological characteristics of O10∶K4 serotype Vibrio parahaemolyticus in a food poisoning case discovered in Fengtai district,Beijing.Methods On October 10 2021,a total of 4 fecal samples of food poisoning cases were went from Sentinel Hospital of Fengtai District,Beijing,with the specimen number FTSY1-4.A total of 30 samples were collected and disposed by CDC,including 13 food samples,15 environmental samples and 2 restaurant water samples.The pathogen was identified by the combination of real-time fluorescent PCR and traditional bacterial isolation.The Vibrio parahaemolyticus strains isolated were serotyped by slide agglutination method,tested for virulence gene tlh/tdh/trh by PCR,tested for antibiotic sensitivity by the method of micro-broth dilution.A pulsed-field gel electrophoresis(PFGE)molecular typing was performed using SfiI enzyme and cluster analysis was performed using BioNumerics v6.0 software.Whole genome single nucleotide polymorphism analysis(wgSNP)was performed using whole genome sequencing(WGS)technique and CSIPhylogeny software.Results There were 4 strains of O10∶K4 serotype Vibrio parahaemolyticus were isolated;all of them were clinical isolates.The 4 strains were all toxin-producing strains,carrying virulence genes tdh,T3SS1 and T3SS2,but not trh.They were all susceptible to 17 antibiotics(Ampicillin,Ampicillin-sulbactam,Cefotaxime,Ceftazidime,Ceftazidime-avibactam,Ertapenem,Meropenem,Azithromycin,Streptomycin,Amikacin,Tetracycline,Tigecycline,Chloramphenicol,Nalidixic acid,Ciprofloxacin,Trimethoprim-sulfamethoxazole,Colistin)and carried blaaRB.22 gene.The results of PFGE showed that the 4 strains had identical banding patterns and 100％homology.The WGS analysis showed that all 4 strains were from the same clone,belonging to ST3 and CC3,and carrying the genes tdh+,trh-,toxRS/new and orf8.Conclusions O10∶K4 serotype Vibrio parahaernolyticus would cause food poisoning outbreak,which has strong pathogenicity and has the possibility of drug resistance and becoming a pandemic strain.Monitoring and analysis should be further strengthened,and preventive propaganda and clinical medication should be strengthened.
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