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Objective To investigate the etiological characteristics of food poisoning isolates of Vibrio parahaemolyticus (VP) from 2019 to 2021 in Zhongshan City. Methods A total of 37 strains of Vibrio parahaemolyticus isolated from 8 food poisoning incidents in Zhongshan City from 2019 to 2021 were collected, including 1 residual food isolate and 36 human isolates. The genetic correlation of Vibrio parahaemolyticus food poisoning isolates in this region was analyzed by serological typing, virulence gene detection (TLH, TDH, and TRH), drug sensitivity test, pulsed field gel electrophoresis (PFGE) and multipoint sequence typing (MLST). Results The 37 strains of Vibrio parahaemolyticus were divided into 4 serotypes: O3:K6, O10:K4, O4:K8, and O4:KUT. The tdh+ and trh- were the main virulence genotypes, accounting for 97.30% (36/37). The drug resistance rate of cefazolin was 40.54% (15 strains R, 22 strains I), and no multidrug-resistant strains were found. The 37 VP strains were divided into 23 PFGE types and 6 cluster groups, with correlation coefficients ranging from 60.4%-100%. The multipoint sequencing typing showed that the 37 VP strains were divided into 9 ST types and 3 complex groups, of which ST3 type was the main type (23 strains, 62.1%). Conclusion This study has found that the dominant virulence types of Vibrio parahaemolyticus food poisoning isolates in Zhongshan City from 2019 to 2021 are tdh+ and trh-, and 37 representative strains can be divided into 6 PFGE clusters and 9 ST types with MLST type being mainly ST3. This study has identified the rare serotype O10:K4 which has caused an increase in the proportion of food poisoning events, suggesting that we should strengthen detection and be alert to the risk of continued local epidemics of new rare serotype strains.
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Objective To study the biological characteristics of clinical isolates of human infected Streptococcus suis type 2 in Zhongshan City from 2016 to 2019 and classify the strains using pulse-field gel electrophoresis (PFGE), and to provide a scientific basis for clinical prevention and treatment of porcine streptococcus suis disease. Methods Twelve strains of Streptococcus suis type 2 were collected from 2016 to 2019 and identified by automatic bacterial identification instrument. The carrying status of five major virulence genes of Streptococcus suis was detected by nucleic acid and protein analyzer, including capsular polysaccharide (cps2J), lysozyme-releasing protein (mrp), hemolysin (sly), glutamate dehydrogenase (gdh), and extracellular factor (ef). The susceptibility of Streptococcus suis to 12 kinds of commonly used antibiotics was determined by the broth microdilution method, and the homology analysis was carried out by PFGE method. Results Twelve strains of Streptococcus suis type 2 were divided into four virulence genotypes, mainly mrp-/sly+/ef+/cps2J+/gdh+ (6strains) and mrp-/sly-/ef+/cps2J+/gdh+(4strains). Drug susceptibility test results showed that 12 strains of Streptococcus suis type 2 were resistant to erythromycin, tetracycline and clindamycin, and they all were multi-resistant strains. According to the classification results of PFGE, the 12 strains were classified into 7 PFGE types based on 100% similarity coefficient. The PFGE band types of Streptococcus suis in the same year had high homology. Conclusion The virulence genotypes of 12 clinical isolates of human infected type 2 Streptococcus suis in Zhongshan from 2016 to 2019 are diverse, and the strains are resistant to multiple antibiotics. Most strains in the same year are the same clone strains. PFGE genotypes are not correlated with virulence genotypes and drug resistance spectrum.
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Objective@#To investigate the sensitivity and specificity of commercial nonstructural protein 1 (NS1) testing kits for Dengue fever diagnose, and provide the evidence for diagnostic criteria revision.@*Methods@#300 PCR or virus isolation positive blood samples for dengue virus were collected from sentinel hospitals for dengue surveillance in Guangzhou, Dongguang and Zhongshang from May 2015 to Nov. 2016. At the same time, 308 PCR negative samples for Dengue virus were collected as control group. The information of the sample was collected using questionnaires. These samples were tested using imported and domestic ELISA and the colloidal gold-labeled kits that were widely used for detecting dengue NS1. Sensitivity, specificity and coincidence were calculated and analyzed, and Z hongshan's result was regarded as the reslut of the third part.@*Results@#The positive group includes 133 males and 167 females, average ages are 47.2±13.3, 179, 110 and 11 of them is Dengue Ⅰ, Ⅱ and Ⅲ respectively. The negative group includes 154 males and 154 females, average ages are (40.1±11.6) years old. The sensitivity of domestic ELISA Kits (94.5%) is less than imported (99.5%), and the result has statistical significance (χ2=8.59, P=0.030), the specificity is 99.7% and 97.7% respectively; The sensitivity of imported and domestic the colloidal gold-labeled Kits is 97.5% and 96.5% respectively, both of specificities are 100%. The sensitivity and specificity of Dengue Ⅰ for NS1 test are more than 97.0%. The sensitivity of domestic ELISA and gold-labeled Kits is 90.0% and 95.0%, and the specificity is 96.8% and 100% respectively for Dengue Ⅱ test. The sensitivity of imported ELISA and gold-labeled Kits is 100% and 98.0%, and the specificity is 99.4% and 100% respectively for Dengue Ⅱ test. The result of the third party show the sensitivity and specificity of domestic ELISA and gold-labeled Kits are 90.0% and 98.0%, the differences has statistical significance (χ2=5.67, P=0.020).@*Conclusion@#NS1 testing can be used as early dengue fever diagnose for higher sensitivity and specificity.
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Objective: To study the relationship between vitamin A (VA) supplementation and the level of IgG antibody to measles strengthened vaccination. Method: Fifty-three school children aged 5-13 years were selected as the test group of VA supplementation, and fifty-two school children as the control group whose ages and sex matched with the test group. The test group was supplicd po the VA pills (2 500IU) at the same time with measles strengthened vaccination for one month. The level of serum VA was analyzed by HPLC. Measles antibody IgG was detected by ELISA. Results: One month after VA supplementation, sernm VA in test group was 376.5?74.2 ?g/L, showing statistical increase over before. The positive rates of measles antibody in the test group were increased from 69.8% to 100%, and the protective rate from 5.6% to 60.4%. The positive rates of measles antibody in the control group were increased from 71.2% to 100%, and the protective rates from 0% to 17.4%. The protective rate in the test group was statistically higher than the control. Conclusion: Simultaneous VA supplementation (especially for the children of VA deficiency) and measles strengthened vaccination contribute to the increase of measles antibody IgG in school children.
