Genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021 / 中华预防医学杂志

Objective: To characterize the prevalence and genomic epidemiology of Vibrio parahaemolyticus from acute diarrheal patients in Shenzhen City from 2013 to 2021. Methods: Based on the Shenzhen Infectious Diarrhea Surveillance System, acute diarrheal patients were actively monitored in sentinel hospitals from 2013 to 2021. Whole-genome sequencing (WGS) of Vibrio parahaemolyticus isolates was performed, and the genomic population structure, serotypes, virulence genes and multilocus sequence typing were analyzed. Outbreak clusters from 2019 to 2021 were explored based on single-nucleotide polymorphism analysis. Results: A total of 48 623 acute diarrhea cases were monitored in 15 sentinel hospitals from 2013 to 2021, and 1 135 Vibrio parahaemolyticus strains were isolated, with a positive isolation rate of 2.3%. Qualified whole-genome sequencing data of 852 isolates were obtained. Eighty-nine serotypes, 21 known ST types and 5 new ST types were identified by sequence analysis, and 93.2% of strains were detected with toxin profile of tdh+trh-. 8 clonal groups (CGs) were captured, with CG3 as the absolute predominance, followed by CG189. The CG3 group was dominated by O3:K6 serotype and ST3 sequence type, while CG189 group was mainly O4:KUT, O4:K8 serotypes and ST189a and ST189 type. A total of 13 clusters were identified, containing 154 cases. About 30 outbreak clusters with 29 outbreak clusters caused by CG3 strains from 2019 to 2021. Conclusion: Vibrio parahaemolyticus is a major pathogen of acute infectious diarrhea in Shenzhen City, with diverse population structures. CG3 and CG189 have been prevalent and predominant in Shenzhen City for a long time. Scattered outbreaks and persistent sources of contamination ignored by traditional methods could be captured by WGS analysis. Tracing the source of epidemic clone groups and taking precise prevention and control measures are expected to significantly reduce the burden of diarrhea diseases caused by Vibrio parahaemolyticus infection in Shenzhen City.

Molecular characterization of Vibrio parahaemolyticus collected from human infections in Shenzhen, between 2002 and 2008 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To determine the occurrence and distribution of specific clones of pathogenic Vibrio parahaemolyticus(VP)isolated in Shenzhen and to assess the relationship between serotype O3:K6 and the globally distributed pandemic clone.</p><p><b>METHODS</b>A total of 1005 VPs isolated from diarrhea patients in 2002-2008 were sero-typed. Real-time PCR was used to detect the virulence genes tlh, toxR, tdh, trh and orf8 in 281 isolates from 68 different serotypes. The main serotypes were typed by pulsed field gel electrophoresis(PFGE). Strains with dominant serotypes and PFGE patterns were assayed by GS-PCR and toxRS sequencing for the identification of pandemic clone. Multilocus sequence typing(MLST)analysis was reserved for exemplary 41 O3 : K6 and O1 : K25 isolates.</p><p><b>RESULTS</b>Seventy-nine serotypes were observed among the 1005 isolates, including O3 : K6(57.9%), O4 : K8(8.16%), O1 : KUT(5.87%), O1 : K25(5.27%), O4 : K68(1.39%), O1 : K56(1.39%) and O9 : K44(0.99%). Most of the strains(99.36%)showed PCR positive to tlh, toxR, and tdh but eleven strains were tdh negative. MLST showed that all the 36 O3 : K6 isolates belonged to ST3 and all the 5 O4 : K8 strains were ST189. These results matched the description of the pandemic VP clone.</p><p><b>CONCLUSION</b>A recognizable burden of diarrheal illness caused by VP had been seen in Shenzhen. Results from serotyping indicated that although there existing a large variety of diversities, the dominant serotype appeared to be O3 : K6. VP isolates identified in Shenzhen mainly showed as tdh positive but trh negative, in consistent with the current pandemic O3 : K6 clone. The pandemic O3 : K6 clone did appear to co-exist with other clones of O3 : K6, as well as O4 : K8,O1 : K25. Potential outbreak of VP could be monitored through the laboratory-based surveillance programs, suggesting that the strategies related to prevention and control of VP should be prioritized in Shenzhen.</p>

Characteristics of Salmonella enterica serovar Senftenberg lacking Salmonella pathogenicity island 1 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the characteristics of the strains of Salmonella enterica (S. enterica) serovar Senftenberg lacking Salmonella pathogenicity island 1 (SPI-1).</p><p><b>METHODS</b>A total of 10 strains of S. enterica serovar Senftenberg were isolated from 10 cases of diarrhea patients. Pulsed field gel electrophoresis (PFGE), PCR, sequencing techniques and cell invasion test were adapted to study the molecular types and invasiveness of the genes and cells; and made a comparison between the 10 strains and the strains (C02013) isolated in Shenzhen in 2002.</p><p><b>RESULTS</b>The 10 Senftenberg isolated (S09007-S09012, S09014-S09017) in Shanghai showed three PFGE patterns, which were significantly different from the strains isolated in Shenzhen. PCR-amplified results indicated the invasion gene (invA), secreted effector protein gene (sipA) and gene fragments as fhlA-hilA, hilA-spaP and spaP-invH in the 10 strains of SPI-1 were all negative. The sequencing results revealed that the 10 strains isolated in Shanghai lacked most parts of SPI-1 genes, as fragments from orgA to invH and parts of orgA gene itself; however, compared with strains isolated in Shenzhen, the sprB-orgC gene existed. The missing parts of genes were replaced by a simple insertion sequence (IS) of 1000 bp in the strains isolated both in Shenzhen in 2002 and in Shanghai in 2006. The invasiveness rates of the 10 strains (S09007-S09012, S09014-S09017) towards Hela cells were (0.0053 ± 0.0024)%, (0.0046 ± 0.0006)%, (0.0047 ± 0.0003)%, (0.0064 ± 0.0012)%, (0.0065 ± 0.0011)%, (0.0070 ± 0.0020)%, (0.0115 ± 0.0030)%, (0.0099 ± 0.0039)%, (0.0180 ± 0.0135)% and (0.0031 ± 0.0012)%, respectively; which were all significantly lower than the rate of invA-positive control strain STM1344 ((5.0800 ± 0.6333)%); lower or close to the rate of invA-lacked artificial-mutated strain STMinvA-((0.0193 ± 0.0045)%).</p><p><b>CONCLUSION</b>SPI-1 genes are not essential for the diarrhea caused by S. enterica serovar Senftenberg.</p>