Abstract:Objective The aim of this study was to determine the effects of elaidic acid on mitochondrial function and autophagy in the human neuroblastoma cell line SH-SY5Y. Methods SH-SY5Y cells were cultured in vitro and treated with different concentrations (0,0, 20,0 and 100 μmol/L) of elaidic acid for 24 hours. The morphology of cells and intracellular autophagosomes were observed by transmission electron microscope. The cell viability was detected by using CCK-8 detection kit. Real-time polymerase chain reaction(PCR)and western blot were used to measure the autophagy-related genes and proteins expression. Results Observation of cell structures found that intracellular autophagosomes formed with 50 and 100 μmol/L of elaidic acid. 50 and 100 μmol/L of elaidic acid might result in a decline in cell viability (P＜0.01). 100 μmol/L of elaidic acid significantly decreased cell viability both after 24 and 48 h (P＜0.05). 100 μmol/L of elaidic acid significantly decreased the cytochrome c (cyt-c) gene mRNA expression in SH-SY5Y cells (P＜0.05). The expression level of cyt-c protein in the cytoplasm was gradually elevated with the increase of elaidic acid concentrations (P＜0.05). But the differences with regard to the LC3B, Beclin1, p62, atg5 and atg12 genes mRNA expression levels of SH-SY5Y cells were not significant across different doses(P＞0.05). 50 and 100 μmol/L of elaidic acid gave rise to the expression of LC3B and Beclin1 proteins up-regulated compared with the normal group (P＜0.05). Conclusion Elaidic acid contributes to the decrease of SH-SY5Y cells viability, which may be associated with the formation of autophagosomes, up-regulating autophagy protein expression, promoting the changes of mitochondrial permeability and releasing mitochondrial cyt-c protein into cytoplasm.

Abstract:Objective To evaluate antimicrobial resistance, virulence and genetic characteristics of Vibrio parahaemolyticus isolated from aquatic products in China. Methods The susceptibility of 1 137 isolates of Vibrio parahaemolyticus from 26 provinces was determined, and virulence genes including tlh, tdh and trh were detected. The genetic characteristics of Vibrio parahaemolyticus were analyzed by pulsed field gel electrophoresis method. Results Two hundred and fifty-four strains (22.3%) were susceptible to all the antibiotics tested and 883 strains (77.7%) presented resistance to single or multiple antibiotics. All strains were susceptible to gentamicin and levofloxacin. The highest resistance rates were ampicillin (53.7%,611/1 137), amoxicillin/clavulanic acid (46.3%,526/1 137) and cefazolin (24.2%,275/1 137). All the 1 137 isolates were positive for tlh gene, including 3 isolates were positive for tdh gene and 19 isolates were positive for trh gene. Twenty strains with virulence genes were resistance to mainly penicillins and cephalosporin and 4 strains of them were snsceptible to all the antibiotics tested. There was no certain relation between the source and drug-resistant spectrum in these strains with virulence genes, and they displayed different genetic characteristics. Conclusion Vibrio parahaemolyticus isolated from aquatic products were resistant to penicillins widely in China, but the rate of virulence genes of strains isolated from food was lower than clinical. The genetic characteristics of virulent strains were varied.

Abstract:Objective To investigate the majority molecular typing characteristics of Cronobacter contamination in powdered infant formula (PIF), analyze the genetic correlation of strains from different provinces, and provide technical support to track diseases of Cronobacter infection in China. Methods Pulsed field gel electrophoresis(PFGE)and multilocus sequence typing(MLST)were used to analysis 49 strains isolated from PIF from 19 provinces in China. Results Totally 49 strains of Cronobacter were divided into 38 clusters, no obvious dominant cluster and aggregation were found. There were 15 ST types and 2 new ST types in 49 strains, ST4, ST1 and ST64 were the dominant types, accounted for 20.4% (10/49), 18.4% (9/49), 10.2% (5/49), respectively. The result of PFGE and MLST showed that strains with the same PFGE type also had the same MLST type, however, the same MLST type was not necessarily related. Conclusion Cronobacter isolated from PIF in China showed highly polymorphism and discreteness, it could predict that the infant infected by Cronobacter contamination in PIF in China was mainly sporadic, the incidence of outbreak of multiple people was low.

Abstract:Objective To assess the prevalence of β-lactam resistance among nontyphoidal Salmonella (NTS) isolates including ampcillin and third-generation cephalosporins, detect the production of ESBL and analyzing their molecular mechanisms, and to provide data basis for relevant diseases control and treatment. Methods NTS isolates were collected from patients, food and river water in Ningbo from 2005 to 2016 and were tested for resistance to ampicillin, cefotaxime and cefotaxime/clavulanate using the disc diffusion method specified in Clinical and Laboratory Standards Institute (CLSI). Among isolates resistant to β-lactam anbiotics, β-lactamase genes (blaCTX-M, blaTEM, and blaOXA) and two types of integrons, class 1 and class 2, were amplified. Results Overall, 893 NTS isolates were obtained from patients, food and river water with resistance rates to ampicillin and cefotaxime, and ESBL-production rate of 37.8%(338/893), 7.7%(69/893)and 7.3%(65/893), respectively. The top three β-lactam-resistant serotypes were Salmonella indiana (100.0%,11/11), Salmonella derby (69.7%,23/33) and Salmonella typhimurium (57.4%,148/258). Other serotypes that were tested positive for cefotaxime resistance and ESBL production were Salmonella agona (4 isolates), Salmonella kentucky (2 isolates) and Salmonella muenster (2 isolates). Ampicillin-resistant isolates mainly contained blaTEM gene. Cefotaxime-resistant isolates often contained blaCTX-M and blaOXA gene. Most β-lactam-resistant isolates were found to have class 1 integron with complete structure. Conclusion High prevalence of ampicillin resistance and moderate prevalence of third-generation cephalosporins resistance existed in NTS isolates from patients, food and river water. High level of β-lactam resistance was found in several NTS serotypes such as Salmonella indiana, Salmonella derby and Salmonella typhimurium. Complicated molecular mechanisms existed in β-lactam-resistant NTS isolates, which might pose great risk to the spread of antibiotic resistance. Strengthened surveillance on β-lactam resistance and exploration of relevant molecular mechanisms were required.

Abstract:Objective To investigate the impact of the Food Safety Law on the epidemiological characteristics of food poisoning and put forward regulatory measures. Methods Descriptive analysis and comparative analysis were carried out based on the data from the public notice of food poisoning incidents from the national health administrative departments for the basic characteristics of food poisoning before and after the implementation of the Food Safety Law in China with the end of 2009 as the dividing line. Results The number of reported food poisoning and the number of poisoned people dropped significantly, and showed a steady trend at a relatively low overall level after the Food Safety Law was implemented. The attribution of food poisoning changed from microbial, toxic animals and plants, chemical and unknown causes to toxic animals and plants, microbial, chemical and unknown causes. The proportion of food poisoning at collective canteens dropped from 32.8% to 22.4%, the proportion of families rise from 38.4% to 49.7%. Families became the most important places where food poisoning occurred. Conclusion After the implementation of the Food Safety Law, the food poisoning situation in China significantly improved; the changes of the causes and places of food poisoning provided the basis for formulating the corresponding prevention measures of food poisoning and the policy of supervision and management.

Abstract:Objective To investigate Staphylococcus aureus contamination in food in Wenzhou, and to analyze the drug resistance, enterotoxin genes distribution and pulsed-field gel electophroresis(PFGE) patterns. Methods According to GB 4789.10-2010 National Food Safety Standard Food Microbiological Examination:Staphylococcus aureus, the strains were isolated and identified. The Kirby-Bauer method was used in drug sensitivity test. Mini-VIDAS and polymerase chain reaction(PCR)were used to detect the Staphylococcus aureus enterotoxin and its genes. All strains were subtyped by PFGE. Results Four categories of 388 samples were collected. Sixteen Staphylococcus aureus strains were isolated with a positive rate of 4.12% and livestock meat and poultry meat got the highest detection rate as 13.89%(5/36)and 11.11%(4/36), respectively. All strains were antibiotic-resistant to at least one drug, and the resistant rate to penicillin was the highest(100.00%,16/16), followed by erythromycin(56.25%,9/16), and 18.75%(3/16)strains displayed multi-drug resistance. No methicillin-resistant Staphylococcus aureus(MRSA) was detected. The prevalence rates were 56.25%(9/16)in enterotoxin and its genes, among which seb and seg gene were more frequently found 37.50%(6/16). The 16 isolates were divided into 12 PFGE patterns. Conclusion The food was contaminated by Staphylococcus aureus to some degree in Wenzhou. Foodborne Staphylococcus aureus isolated in Wenzhou showed molecular polymorphism and strong enterotoxin-producing ability. The prevalence rates of enterotoxin gene was high, which may result in potential risks to food safety.

Abstract:Objective The 3MTM PetrifilmTM rapid yeast and mold count plate (RYM) method and the national standard method (GB 4789.15-2016) were compared for the consistency in yoghourt detection, and the specificity of the PetrifilmTM RYM was assessed. Methods Two quality control samples, 78 reference strains and isolated strains of yeast and mold, 50 yoghourt samples and 50 artificially contaminated yoghourt samples were detected by both method. Then the data of the two method were analyzed by the paired t test and the log difference (|dlog|); and PetrifilmTM RYM method was used to detect non-mold-yeast strains for specificity. Results There was no significant difference (P>0.05) among different samples in paired t test, and the ratio of |dlog|≤0.50 were 100.0%. There was no significant difference between the two method. The result of the yeast and mold count in non-mold-yeast strains were blank, indicating that the PetrifilmTM RYM had good specificity. Conclusion There was no significant difference between the result of the PetrifilmTM RYM method and the GB 4789.15-2016 method in detecting quality control samples, strains of yeast and mold, yoghourt samples and artificially contaminated yogurt samples, and the PetrifilmTM RYM had good specificity.

Abstract:Objective To investigate the aerobic plate count and somatic cell count of raw milk in China, and analyze how the factors of breeding patterns and breeding areas influence the aerobic plate count and somatic cell count of raw milk. Methods Statistic of aerobic plate count of 17 527 raw milk samples and somatic cell count of 6 633 raw milk samples were collected, during 12 consecutive months from 2014 to 2015 in 17 provinces (municipalities and autonomous regions). The Kruskal-Wallis rank sum test was applied to analyze how the factors of breeding patterns and breeding areas influence aerobic plate count and somatic cell count by SPSS 19.0 software. Results The average aerobic plate count of raw milk in China was 3.27×10⁵ CFU/ml.The average somatic cell count of raw milk in China was 4.60×10⁵/ml.The median of aerobic plate count of raw milk produced in large-scale dairy farms, farming communities and household farmers were 1.00×10⁵, 1.85×10⁵ and 2.37×10⁵ CFU/ml respectively. The medians of somatic cell count of raw milk produced in large-scale dairy farms, farming communities and household farmers were 3.50×10⁵,7.30×10⁵ and 5.91×10⁵ /ml respectively. The medians of aerobic plate count of raw milk produced in the northeast China and Inner Mongolia, the north, the south, periphery of big cities, the west were 2.40×10⁵,1.43×10⁵,1.50×10⁵,1.60×10⁵ and 2.14×10⁵ CFU/ml respectively, and the median of somatic cell count were 5.72×10⁵,3.30×10⁵,3.82×10⁵,5.60×10⁵ and 4.00×10⁵/ml respectively. Conclusion The aerobic plate count of over 99% of raw milk in China met the requirement of the national standards.There was room for improvement of aerobic plate count limit in safety standards. The aerobic plate count and somatic cell count of raw milk produced in large-scale dairy farms were lower than those of other breeding patterns.

Abstract:Objective To understand the epidemiological and clinical characteristics of Norovirus in foodborne diarrhea cases in Jinan. Methods Fecal specimens, data of clinical symptoms and epidemiologic records were collected from two active monitoring sentinel hospital from January 2014 to December 2016 in Jinan. Results Totally 1 292 specimens of cases were collected. The positive rate was 18.58% (240/1 292), of which GII type accounted for 75.42%(181/240). There were no gender difference in the positive rate of positive cases, GI and GII cases (P>0.05); There were significant differences between age groups in positive rates of two genotypes (χ²=27.912,P<0.001；χ²=42.285, P<0.001). The detection rate of Norovirus in the first and fourth quarters were higher than the other quarters, with seasonal distribution characteristics. The main symptom was simple diarrhea in 240 positive cases (54.17%,130/240), followed by diarrhea + vomiting symptoms (18.75%,45/240). The intensity of diarrhea was normally moderate, and the average frequency of diarrhea was 5.82 times/day. The fecal were mainly water samples, which accounted for 93.75%(225/240). The radio of vomiting symptoms was about 30.00%(72/240)in virus-positive cases, and the vomiting frequency was mainly 1-2 times/day. The most frequent suspected exposure food was meat products, followed by sea food and dairy products. Conclusion The main type of Norovirus was GII genotype in foodborne diarrhea cases in Jinan. Norovirus was popular throughout the year with seasonal distribution characteristics. Infants were the most susceptible group. And simple diarrhea and diarrhea + vomiting symptoms were the main clinical symptoms of Norovirus infection. The monitoring, identification and prevention of foodborne diarrhea cases should be improved according to the seasonal characteristics, the different susceptible population and the different characteristics of the suspected food.

Abstract:Objective To understand the prevalence and epidemiological characteristics of poisonous mushroom poisoning in Zhejiang Province, and to provide scientific basis for the early warning and prevention and control of mushroom poisoning. Methods The epidemiological characteristics of mushroom poisoning outbreaks in Zhejiang Province reported by the Foodborne Illness Outbreak Monitoring System during 2010-2016 were analyzed by descriptive analysis. Results A total of 42 mushroom poisoning outbreaks were reported in these 7 years. There were 192 cases of poisoning and 13 cases of death. The number of deaths accounted for 76.5% (13/17) of the total deaths from foodborne illness in the province. The year with the most incidence was 2016, accounting for 40.5% (17/42) of the total. June to October was the peak time of mushrooms poisoning, accounting for 95.2% (40/42) of outbreaks and 97.9% (188/192) of cases of poisoning respectively. The cases of death were all reported during June to August. The majority of mushroom poisonings occurred in family setting, accounting for 83.3% (35/42) of the total incidence. Hangzhou, Jinhua and Shaoxing were the top three cities with the most outbreaks, while Ninghai County, Tonglu County and Shengzhou City were the top three counties (cities, districts). The main symptom was gastroenteritis, accounting for 72.4% (139/192) of all cases of poisoning. The incubation period varied from 18 min up to 15 h, with the median of 2 h. In two outbreaks involving severe organ damage cases, the peptide toxins of Amanita mushrooms were detected. Conclusion Poisonous mushroom poisoning was the main cause of death from foodborne illness in Zhejiang Province. Countermeasures should be taken to monitor and intervene in high-incidence seasons, high-incidence areas and high-risk populations, and to improve the general public's capability of self-protection.

Abstract:Objective To investigate an acute gastroenteritis outbreak and discuss the methodology of etiology screening. Methods Cases were identified according to the definition. Descriptive epidemiological approaches and case-control study designs were employed in the analysis. All the samples were tested for common pathogens by isolation. Results A total of 43 cases were found. Epidemiological curve suggested that it was a point source outbreak and the major symptoms were diarrhea (100.0%,43/43),abdominal pains (93.0%,40/43),nauseous (32.6%,14/43) and so on. Results From the case-control study revealed that the roast duck served at lunch on September 12 was suspectable. A total of 36 samples, including rectal swabs from patients, hand swabs from kitchen workers, leftover food and environmental swabs, were collected.Five samples (collected from 13 patients) were positive. Conclusion This was a suspected foodborne outbreak of Clostridium perfringens. The possible cause was that the roast duck was contaminated by Clostridium perfringens when stored in the external environment at room temperature for about 5-6 h and was directly ate by patients without reheating. It is necessary to strengthen the supervision and administration of chefs, and improve health consciousness of the public to prevent such case. Investigators should abandon the “lab-dependent” way and strengthen the summary of symptoms-based epidemiology related to a variety of agents so as to decreases the rate of erroneous diagnosis and misdiagnosis dued to the unfamiliar of symptoms of various foodborne diseases.

Abstract:Objective To analyze the epidemiological feature of foodborne acute diarrhea among children in Qinghai, and to provide references for foodborne acute diarrhea control and prevention. Methods Suspected foodborne acute diarrhea cases during 2013-2016 were collected from 13 sentinel hospitals of Qinghai among children aged less than 4 years and feces or swab samples were collected for pathogenic analysis. Four kinds of bacteria (Shigella spp., Salmonella spp., diarrheagenic E.coli and Vibrio parahaemolyticus) and one kind of viruses (Norovirus) were detected. Results A total of 3 068 foodborne acute diarrhea among children aged less than 4 years were enrolled. The main character of feces was watery stool, and 54.66% (1 677/3 068) had fever. There were 150 positive cases, and the total positive rate was 4.89% (150/3 068). The highest positive rate was Shigella spp., which was 2.36% (72/3 049), followed by Salmonella spp. of 2.11% (64/3 035), and the positive rate of Norovirus was 1.02% (10/983). The foodborne acute diarrhea among children was mainly occurred during the summer and autumn. The positive rate of infants (<1) was higher than that of infants (1-3). Milk products were the main suspected food. Conclusion The main pathogen was Shigella spp. and Salmonella spp. among children of in Qinghai Province, and Norovirus was also detected. It was necessary to strengthen the surveillance capacity and the publicity of foodborne acute diarrhea knowledge among children,also to carry out more effective preventive and control measures.

Abstract:Objective To study the epidemiological characteristics of foodborne disease outbreaks in China mainland in 2011. Methods The foodborne outbreaks data collected by National Foodborne Disease Outbreaks Surveillance System were analyzed. Results Total 809 foodborne outbreaks were reported from 29 provinces, which caused 14 057 illnesses and 113 deaths. The microbial pathogens caused the largest percentage of outbreaks (26.2%,212/809) and illnesses (37.6%,5 292/14 057). Chemical agents caused the most deaths (39.8%,45/113). Conclusion Microbial foodborne disease remains the first priority of food safety problems in China. Chemical agents are the main cause of death. National foodborne disease network should be strengthened continuously, meanwhile, reporting consciousness should be enhanced

Abstract:Objective To study the epidemiological characteristics of foodborne disease outbreaks in China mainland in 2012. Methods The foodborne outbreaks data collected by National Foodborne Disease Outbreaks Surveillance System were analyzed. Results Total 917 foodborne disease outbreaks were reported in 30 provinces, which caused 13 679 illnesses and 137 deaths. The microbial pathogens caused the largest percentage of outbreaks (27.81%,255/917) and illnesses (50.03%,6 844/13 679). Poisonous mushrooms caused the largest percentage of deaths (55.47%,76/137). 41.77%(383/917)and 34.68%(318/917)outbreaks were associated with food prepared in private home and restaurant, respectively. Conclusion Microbial pathogens were the most common cause of foodborne outbreaks in China. More attention should be paid on education of the poisonous mushrooms.

Abstract:Objective To study the epidemiological characteristics of foodborne disease outbreaks in China mainland in 2013. Methods The foodborne disease data collected by National Foodborne Disease Outbreaks Surveillance System were analyzed. Results Total 1 001 foodborne disease outbreaks were reported in 30 provinces, which caused 14 413 illnesses and 90 deaths. Microbial pathogens caused the largest percentage of outbreaks and illnesses, accounting for 32.0% (320/1 001) and 49.7% (7 162/14 413) respectively, poisonous mushrooms caused the largest percentage of 52.2% (47/90). Conclusion Microbial foodborne disease were the first priority of food safety problems in China. Vibrio parahaemolyticus and Salmonella were the most common foodborne pathogens. Poisonous mushroom poisoning cannot be ignored.

Abstract:Objective To find out the cause and risk factors of the outbreak of food poisoning, and to provide evidence for the prevention and control of food poisoning. Methods Field epidemiological investigate method and case-control study method were used to analyze the suspicious meals of exposure. Field hygienic investigation was carried out. Samples were collected for laboratory testing. Results Totally 156 cases were found in the survey. The attack rate was 8.30%(156/1 879)and the main clinical symptoms were diarrhea (99.4%,155/156), stomachache (81.4%,127/156), nausea (16.7%,26/156) and vomiting (3.8%,6/156). The result of case-control study demonstrated that the dinner of October 24th was the suspected meal (OR=49.91,5%CI=12.93～192.63). The attack rate showed statistical significance in different classes(χ²=115.56,P＜0.01). A total of 107 samples were detected in the laboratory, and Enterobacter sakazakii were detected in the patient's anal swab, the delivery car, the delivery containers and the cooked meat with bean curd in the sample food. Conclusion The epidemic situation was a foodborne disease outbreak caused by suspected Enterobacter sakazakii infection. The poisoning might be caused by the cooked meat with bean curd during dinner on 24th October. It was recommended to strengthen supervision of foodservice industry to prevent such incidents from happening again.

Abstract:Objective To analyze the pathogenic substance, cause of pollution, cause of unidentified food contamination of 278 outbreaks of unexplained foodborne disease, offer suggestions and provide reference for identifying the pathogenic substances. Methods The data of unexplained foodborne disease outbreaks between 2010-2016 from Foodborne Disease Outbreak Surveillance System was collected, and then sorted and analyzed with Microsoft Excel software. Results A total of 436 foodborne disease outbreaks were reported in Shanxi province from 2010-2016, among which 278(63.76%) were unexplained foodborne disease. These 278 events, with less than 100 patients each, all were general food safety accidents. 40.65%(113/278)of the events occurred in the third quarter. The symptoms of digestive system were the major clinical situation, and 74.76%(1 303/1 743)cases had with abdominal pain. The most common setting was catering service establishment (49.64%,138/278). 30.51%(83/272)of the events collected samples, while only 2.90%(4/138)collected all four types of samples(including food samples, patients' biological specimens, employees' biological specimens and environmental samples) in catering service establishment.There were 137 events occurring after people eating together many times, among which only 18.25%(25/137)investigated the multiple meals,16.79%(23/137)investigated unaffected person after sharing the same suspicious meals, and only one event carried on the analytical research. There were 138 events occurring in catering service establishment, among which only 54.35%(75/138)carried out investigations of food hygiene, but not comprehensive. Conclusion There were many events with unidentified pathogenic substance, unidentified cause of pollution, unidentified contaminated food as well as unidentified triggering link. The reasons for this included imperfect investigation mechanism, outdated diagnostic criteria, insufficient inspection equipment and ability, absent of qualification of food inspection, nonstandard sample collection, inadequate epidemiological investigation, administrative intervention as well as the influence of social factors.

Abstract:Objective To study the application of different cumulative risk assessment method in evaluating risk of combined exposure of chemicals, based on the exposure data of lead and cadmium in typical beverage consumers. Methods Concentration data of lead and cadmium of beverages and beverage consumption data were used to calculate beverage exposure of lead and cadmium among three groups of beverage consumers. The scientific literature was used to obtain the toxicological data and health guideline values of lead and cadmium, and the control level of heavy metals in beverages was assumed to be less than 5% of the health guideline value. Based on the principle of grading assessment, the cumulative risk assessment method of hazard index(HI),target-organ toxicity dose(TTD) and weight-of-evidence(WOE) were used to assess the combined exposure risk of lead and cadmium, and also compared with the result of single substance exposure. Results In comparison with 5 percent of the health guideline value, middle school students exposed to lead through beverage exceeded this value. The result of HI method showed that the HI values of the middle school and college students' beverage consumers were greater than 1. The result of TTD method showed that the HI values of combined exposure of lead and cadmium to kidney were greater than 1 in three groups. For the cardiovascular and neurological system, only HI value of middle school students was greater than 1. For other endpoints, the HI values of the three groups were less than 1. The result of WOE method showed that the adjusted HI values for the interaction between lead and cadmium exposed to the cardiovascular and nervous system in middle school students were greater than 1. Conclusion Different cumulative risk assessment method could be used to assess the cumulative risk of combined exposures to different chemicals in foodstuffs. The appropriate method could be selected using the principle of grading assessment based on the adequacy of supportive data and management needs.

Abstract:Objective Assessing the risk-benefit of nitrate in vegetables, and to provide the guidance for risk-benefit assessment in food or nutrient. Methods Primary and secondary risk-benefit assessment for nitrate in vegetables was performed on the basis of BRAFO (benefit risk analysis for food) model, combined with intake assessment of nitrate and qualitative comparison of nitrate in vegetables. Results The average vegetable consumption of Chinese resident changed from less than 300 to 300-500 g/d, the benefits were larger than risk, alternative scenario was superior to reference scenario which was recommended. Conclusion The method of grading assessment of risks and benefits of food is scientific and reasonable, which need to further strengthen the research of epidemiology and toxicology, to optimize the model parameters. Combining probabilistic assessment with the risk-benefit assessment studies could reduce the uncertainty.

Abstract:Objective To explore a new way to conduct follow-up evaluation for national food safety standards and build rudimentary indexes to evaluate the quality of national food safety standards. Methods The suggestions for national food safety standards from stakeholders were collected through the ‘tracking evaluation and feedback platform for food safety standards'. The high frequency keywords were selected and the suggestions were classified into different groups depending on the content. The type of suggestions reflected the perspectives of stakeholders. According to the result of classification, the evaluation dimensions for national food safety standards were generalized from the suggestions. Results Totally 873 valid suggestions were collected through internet platform from January to August 2017. The high frequency keywords were ‘inspection & method', ‘index & limit’,‘label & mark’,‘scope & classification’. Four evaluation dimensions, including the ‘relevance’ of standard project or revision, the ‘science’, ‘achievability’ and ‘coordination’ of the standard, and fifteen indexes under the four dimensions were generalized from the suggestions. Conclusion Through analyzing the suggestions, the rudimentary two-level assessment index system was developed. The assessment of national food safety standards should emphasis on the relevance of standard project or revision, the science base of standard text, the achievability of standards and the coordination with related policies and regulations.

Abstract:Objective To investigate the source of a food poisoning case in a rural wedding banquet based on the PFGE analysis of the pathogenic bacterium isolated from the patient anal swabs and polluted external environment samples. Methods Etiological examinations of 20 specimens were performed. Serological typing, pulsed-field gel electrophoresis (PFGE) analysis and tdh, trh, tlh, toxR genes test were carried out on the Vibrio parahaemolyticus (VP) detected. Results Fifteen strains of VP were isolated from 20 samples. Gene tests showed that 11 specimens were tdh, tlh, toxR genes positive, while 4 were tlh, toxR genes positive. Nine out of 12 patient anal swab samples were VP positive, of which 7 were O3∶K6 serotype, while the remaining were O2 group; All 3 chopping block daub samples were VP positive, of which 2 were O3∶K6 serotype, the third one was O1 group; 2 out of 3 remaining foods were VP positive, which were O1, O10 group respectively. The anal swab sample of the chef was O11 group positive. PFGE analysis revealed that the O3∶K6 of the patient anal swabs and chopping block daub samples were highly homologous. Conclusion This was a food poisoning outbreak caused by multiple serotypes of VP mainly by O3∶K6, which might be contaminated through chopping block.