Abstract:Objective To investigate the serotype distribution and antimicrobial resistance characteristics of Salmonella isolated from retail chicken in Beijing City.Methods A total of 135 Salmonella strains were isolated from retail chicken meat collected from three large wholesale markets in Fengtai District in Beijing City from 2014 to 2015. The serotype of these Salmonella strains was identified using both a Luminex serotyping kit and a traditional serum agglutination method. Multilocus sequence typing was performed according to the recommended conditions of the Enterobase database. Antimicrobial susceptibility testing plates were used to determine the susceptibility of the isolates against 12 classes of drugs representing 25 antimicrobial agents. PCR was used to detect the prevalence of the 10 mobile colistin resistance genes （mcr） and three NDM-type carbapenemases genes （bla_NDM）.Results Among the 135 Salmonella strains， 6 serogroups were detected， with D1 and B being the main serogroups； 20 serotypes were detected， in which Enteritidis， Indiana， and Thompson were the dominant ones with percentages of 50.4%， 15.6%， and 8.1%， respectively； 21 ST types were obtained， and a good correspondence was observed between serotypes and ST types. 91.9% of all tested isolates showed resistance to the tested drugs and showed the highest resistance to nalidixic acid， ampicillin， ampicillin-sulbactam， tetracycline. Multi-drug resistant strains accounted for 71.1% of all strains and were resistant to as many as 18 kinds of antimicrobial compounds belonging to 10 categories. Among the 17 strains co-resistant to 8 or more classes of drugs， 16 were of the Indiana serotype. The proportion of strains with high multi-drug resistance was different in different packaging methods， different seasons， and different wholesale markets. All strains were negative for the mcr and bla_NDM genes.Conclusion The serotypes of Salmonella isolates from chicken meat in wholesale markets in Beijing City from 2014 to 2015 were complex， with the dominant serotype of Salmonella Enterititis， and the overall antimicrobial resistance level of all isolates was high. To assess the possible food safety risks， continuous monitoring for Salmonella Indiana with high levels of antimicrobial resistance must be carried out and their drug resistance and transmission mechanisms must be studied to help develop first-line and ultimate drugs for clinical treatment of Salmonella diseases.

Abstract:Objective To study the migration rule of melamine and formaldehyde under acidic conditions in bamboo fiber-melamine resin （BM） tableware， discuss the main factors affecting the migration level and safety risks， and provide suggestions for the safety management of such products.Methods A total of 14 brands of BM tableware （including baby and infant tableware） with clear identification of bamboo fiber in the market were collected. Ethanol （10%， V/V）and acetic acid （4%， V/V）were selected， and the tableware were soaked in according to GB 5009.156—2016， and then conduct migration tests under acidic conditions according to the national food safety standards GB 31604.15—2016 and GB 31604.48—2016.Results When BM tableware was exposed to 4% （V/V） acetic acid， the migration level of melamine and formaldehyde was much higher than that of 10% （V/V） ethanol. For a single sample， the migration trend of melamine and formaldehyde was positively correlated， and long-term repeated exposure to more acidic food may have caused a higher chance of excessive migration. With increased frequency of use， the migration level of melamine and formaldehyde increased gradually， which was more obvious in the products with higher bamboo fiber addition.Conclusion The migration rules of melamine and formaldehyde in BM tableware were basically the same after long term repeated use. The migration level of melamine better reflected the decomposition of resin. BM tableware had a higher chance of excessive migration when repeatedly contacting acidic food for a long time， especially for infant products. The guidance on labels and consumer education should be strengthened and the use of non-conforming raw materials should be eliminated to promote the development of the industry within safety standards.

Abstract:Objective To analyze the contamination and drug resistance characteristics of Bacillus cereus isolated from raw vegetable.Methods One hundred and twenty raw vegetable samples were collected in this study in Beijing City， Shuiyi District from May to September in 2021. Plate counting， bacterial culture， real-time PCR for the ces vomiting toxin gene and the 16S rDNA gene of B. cereus were performed. Drug resistance to 14 antibiotics in B. cereus strains were determined.Results The positive ratios of B. cereus in raw vegetable samples was 84.17% （101/120）. Significant differences were observed in the positive ratio of B. cereus between rhizome and leaf vegetables （χ²=14.181， P=0.000 correction）， in the positive ratio of B. cereus （χ²=11.050， P=0.004） in supermarkets， agricultural markets， and farmland， and also in the positive ratio of ces on enriched samples （P=0.001 Fisher）. Average Ct values of 16S rDNA and ces by real-time PCR in 12 ces+ enriched samples were 19.96 and 31.80， respectively； however， ces⁺ B. cereus was not isolated. The drug resistance ratios of B. cereus isolates to AMP， PEN， and SXT were 100%， 99.01%， and 61.39%， respectively. Five patterns of drug resistance distribution were observed and the dominant pattern was AMP+PEN+SXT （59.41%）； the multidrug resistance ratio （resistant to three or more classes of antibiotics） was 0.99% （1/101）.Conclusion B. cereus and the ces gene were widely distributed in local raw vegetable samples with a low level of multiple drug resistance in the isolates. ces⁺ B. cereus was present in low proportions in the B. cereus flora in s single sample of raw vegetable.

Abstract:Objective To study test time and temperature of specific migration tests for hot drink cup through a questionnaire and a laboratory real temperature measurement method.Methods The consumption habits of consumers were investigated by means of questionnaires， the estimated time of contact with food during the general actual use of the hot drink cup was obtained， and the migration time required for the specific migration quantity test of the hot drink cup was obtained. Using real food to reproduce the actual use of the hot drink cup in a simulated consumption environment， and using an automatic temperature recorder to record the temperature changes during the test， the migration temperature required for the specific migration test of the hot drink cup was obtained.Results According to the survey results of consumers’ consumption habits in a restaurant， most consumers， in the process of eating in the restaurant， had an actual contact time with a hot drink cup of 1 h. According to the temperature measurement results during the actual use of the hot drink cup， its average temperature in different conditions within 1 h was 60 ℃-66 ℃.Conclusion According to a questionnaire and measured temperatures， it is recommended that a specific migration test condition of 70 ℃ for 1 h is selected. This study on specified migration conditions， including duration and temperature， was conducted through investigation and measurements and can be used as a reference to relevant testing institutions and laboratories when testing dine-in hot drink cups.

Abstract:Objective To detect enterohemorrhagic Escherichia coli （EHEC） O157：H7， visualization recombinant enzyme polymerase amplification （RPA） detection and real-time fluorescence RPA detection methods were established based on RPA technology.Methods Primers and probes were designed based on the rfbE gene of EHEC O157：H7， and specificity and sensitivity were determined. A real-time fluorescent RPA method was established. Combined with the color change characteristics of SYBR Green I in nucleic acid reactions， a visualization RPA method for the detection of EHEC O157：H7 was established.Results The established real-time fluorescence RPA detection and visual RPA detection methods both detected EHEC O157：H7 in 25 min at a reaction temperature of 35 ℃. The designed primers and probes showed specific results only for EHEC O157：H7. The detection limits of the two methods were lower than 10^-5 ng/μL.Conclusion The visual RPA detection and real-time fluorescence RPA detection methods of EHEC O157：H7 were easy to operate with strong specificity and high sensitivity. This study provides novel methods for the rapid detection of EHEC O157：H7 in the field and laboratory.

Abstract:Objective To investigate the contamination levels of indicator polychlorinated biphenyls （PCBs） in pork in China and the dietary exposure and risks of Chinese residents.Methods The concentration of seven indicator PCBs （PCB 28， PCB 52， PCB 101， PCB 118， PCB 138， PCB 153， and PCB 180） in 203 pork samples from 13 provinces （autonomous regions， centrally administered municipality） in China in 2020 as monitoring sites were analyzed by combined isotope dilution-gas chromatography-high resolution mass spectrometry. The health risk of the population exposure of indicator PCBs through pork was assessed in conjunction with date on pork consumption in each province.Results The mean concentrations of the seven indicator PCBs （∑₇PCBs） in pork ranged from 0.053 （Guangxi） to 0.826 ng/g fat （Zhejiang）， and P₉₅ concentrations ranged from 0.091 （Guangxi） to 2.702 ng/g fat （Zhejiang）. PCB 28 and PCB 52 were the main fingerprint features. The mean and P₉₅ levels of ∑₇PCBs ingested daily by Chinese residents through pork consumption were 0.062±0.076 （ng/kg·BW） and 0.158±0.207 （ng/kg·BW）， respectively， and the exposure risk index （ERI） was less than 1.Conclusion The contamination level of ∑₇PCBs in pork in China， as well as the health risk of residents exposed to indicator PCBs through a pork diet was low.

Abstract:Objective To understand the consumption of dendrobium officinale， by residents in nine Chinese provinces， and assess the cumulative levels of exposure related to four heavy metals （lead， cadmium， mercury， and arsenic） in dendrobium officinale consumers.Methods Consumption data from nine Chinese provinces from 2019 and 2022 and a literature review were used based on a simple distribution model and the hazard index （HI） method to assess the health risk of four heavy metals .Results Consumers mainly preferred dried dendrobium officinale （37.3%） and commonly consumed it by brewing tea or cooking soup. The average value of a single consumption amount was 8.2 g/person. Fresh dendrobium officinale was consumed by 12.9% of the surveyed population， primarily through juicing with an average single serving size of 30.8 g/person. The exposure assessment results indicate that in the case of dendrobium officinale （dried/fresh）， the exposure levels of four heavy metals exposure in dried products were consistently higher than in fresh ones. Additionally， the average exposure level of lead （dried/fresh） was the highest； arsenic exposure levels for different gender-age groups were above the health guidance value or 5% reference dose ［Margin of exposure （MOE>1）］. Average lead exposure exceeded the standard （MOE>1）， whereas the 95th percentile （P95） values exposure were below 1 （MOE<1）. Cadmium and mercury exposure levels are below the 5% health guidance value.The assessment results of heavy metal exposure in residents consuming dendrobium officinale in different provinces indicate that residents in Jiangxi Province have the highest levels of exposure to four types of heavy metals. The MOE values for high-end exposure to lead in both Jiangxi Province and Zhejiang Province are less than 1. The cumulative assessment of 4 elements indicates that the HI values for consumers of dendrobium officinale are all less than 1.Conclusion Consumers of dendrobium officinale in China have low health risks associated with arsenic， cadmium， and mercury exposure. However， individuals with high food intake individuals should pay attention to the health risks associated with lead exposure.

Abstract:Objective To analyze the contamination of aquatic products with pathogens in Yunnan Province and provide a basis for the prevention and control of foodborne diseases.Methods From 2014 to 2021， aquatic products obtained from 16 cities in Yunnan Province were randomly used for pathogen detection， and statistical methods were used to analyze the differences in product type， regional and seasonal distribution， and contamination source between varied aquatic products.Results A total of 3 540 samples were collected in the four categories of aquatic food， fresh aquatic animals， cold aquatic animals， frozen surimi products， and ready-to-eat products. Nine pathogenic microorganisms and one parasite were detected， with a total detection rate of 10.8%. Vibrio parahaemolyticus （10.3%）， Listeria monocytogenes （4.2%）， and Salmonella （3.3%） were the most common pathogenic microorganisms. Angiostrongylus cantonensis was commonly present in intermediate hosts （9.0%）， whereas the detection rate of other pathogens was low. The detection rates of pathogens in different aquatic products were statistically different （χ²=34.077，P<0.001）， mainly in fresh and cold aquatic animals. The chi-square test showed differences in the regional distribution， origin， and environments of some pathogens. The detection rates of V. parahaemolyticus （χ²=15.850， P=0.001） and Vibrio alginolyticus （χ²=8.400， P=0.029） were statistically different in a seasonal distribution.Conclusion The contamination of aquatic products by pathogens was common in Yunnan Province， and this is a risk factor for foodborne illness. Changing dietary habits， improving aquatic product storage and transportation conditions， and strengthening pathogenic microorganism monitoring are effective ways to reduce the incidence of related food-borne diseases.

Abstract:Objective To analyze the contamination of Salmonella， Listeria monocytogenes （L. monocytogenes）， and Yersinia enterocolitica （Y. enterocolitica） in raw poultry meat and prepared meat products in Shanghai City.Methods From January to August in 2022， 348 samples were collected from traditional markets， supermarkets， and restaurants in Shanghai City， including 240 raw poultry meat and 108 prepared meat products. The samples were evaluated for the presence of Salmonella， L. monocytogenes and Y. enterocolitica following national standard methods. All suspected isolates were further confirmed with the VITEK2 automatic biochemical identification method， and all Salmonella isolates were serotyped.Results The detection rates of Salmonella， L. monocytogenes and Y. enterocolitica in raw poultry meat were 28.33% （68/240）， 5.00% （12/240）， and 0.83% （2/240）， respectively， and in prepared meat products were 5.56% （6/108）， 28.70% （31/108）， and 1.85% （2/108）， respectively. Serotyping results showed that 68 strains of Salmonella were distributed in 14 different serotypes in raw poultry meat， of which Salmonella Corvallis， Salmonella typhimurium， and Salmonella enteritidis accounted for 35.29%，16.18%， and 13.24%， respectively. Six strains of Salmonella in prepared meat products were distributed in three different serotypes. They were Salmonella enteritidis， Salmonella Kentucky， and Salmonella typhimurium accounted for 66.67%，16.67%， and 16.67%，respectively .Conclusion The contamination rate of Salmonella and L. monocytogenes in raw poultry meat and prepared meat products in Shanghai City was high， which may cause foodborne diseases and more attention should be paid in the follow-up supervision.

Abstract:Objective To provide basis for further improving the standards management of food enterprise in China， the current situation and the “stricter” indicators of food enterprise standard filing in China was analyzed， and the standard management situation of food enterprises in China was systematically understood.Methods Querying the provincial government service network， the official website of the Health Commission， and the food enterprise standard filing information platform were collected， and the food enterprise standard filing work and the “stricter” indicator filing in China were sort out and analyzed.Results There were certain differences in the standard filing system， scope， organization， and handling methods of food enterprises in various provinces. In December 2022， 4 380 food enterprise standards were filed in China， with 91.44% （4 005/4 380） for common food at most. From the category of filling indicators， the highest proportion of pollutant indicators was 93.16% （3 707/3 979）， and the highest proportion of lead in all indicators was 83.66% （3 329/3 979）. 83.55% （3 195/3 824） of food enterprise standard “stricter” indicators was 0%-20%.Conclusion There are significant differences in work modes among different provinces， and the quality of food enterprise standards filing is not high. Most filing standards use lead as a “stricter” indicator， and the majority are stricter than the percentage below 20%. The effect on improving the level of food safety management and product quality is not obvious. It’s suggested to optimize the food enterprise standard filing system and explore the feasibility of building a national enterprise standard filing information platform.

Abstract:Pre-packaged complementary foods for infants and young children are an important part of their diet. The standards of international organizations， some developed countries， and China for infant and young child complementary foods are briefly introduced in this article. Based on investigations and research， the major problems in “National food safety standard Cereal supplementary foods for infants and young children” （GB 10769—2010） and “National food safety standard Canned supplementary foods for infants and young children” （GB 10770—2010） were analyzed， and a preliminary standard revision direction was explored to provide a reference for the revision of national food safety standards for infant and young child complementary food.

Abstract:Objective To obtain the occurrence time and regional distribution characteristics， place of occurrence， high-risk food and risk factors， the epidemiological characteristics of foodborne disease outbreaks caused by Vibrio parahaemolyticus from 2010 to 2020 in China’s Mainland was analyzed.Methods The data of foodborne disease outbreaks caused by Vibrio parahaemolyticus were collected from China disease outbreak surveillance system from 2010 to 2020 were analyzed statistically.Results From 2010 to 2020， a total of 1 772 outbreaks of foodborne diseases caused by Vibrio parahaemolyticus were reported， with a total of 27 212 cases， 5 944 hospitalized cases and 2 deaths. The peak time was from July to September. The incidence in developed areas （28.8 cases/million people） was higher than that in underdeveloped areas （8.2 cases/million people）， and the incidence in coastal areas （31.7 cases/million people） was higher than that in inland areas （9.2 cases/million people）. The main causes were aquatic food （61.2%） and meat （25.3%）. Hotels and restaurants accounted for 49.6% of the total. The main contamination links were incomplete cooking of aquatic food and raw and cooked cross-contamination of ready-to-eat meat and vegetable food.Conclusion In order to reduce the risk of foodborne diseases caused by Vibrio parahaemolyticus， it is important to strengthen the supervision of processing and storage of aquatic food and meat in catering service places.

Abstract:Objective To prevent the recurrence of nitrite poisoning caused by siphonage through a waterpipe siphon， its causes were investigated and analyzed， and prevention and control measures are discussed.Methods A field epidemiological investigation， hygiene investigation， and laboratory testing were used to identify causes and possible sources of contamination in this poisoning event.Results A total of nine cases were found with cyanosis （100.00%）， fatigue （66.67%）， and nausea （55.56%）. The epidemiological curve showed one point source exposure pattern， with an interval of 50 min between the first and last cases and an average incubation period of 20 min. Different concentrations of nitrite were detected in vomit， residual food， and tap water. A negative correlation was observed between nitrite concentration in vomits and diastolic blood pressures （r_s=0.798， P<0.05）. Patient symptoms were significantly relieved after receiving specific treatment for nitrite poisoning.Conclusion This incident was caused by an anticorrosive solution containing nitrite in pickling tanks flowing back into the tap water pipeline through siphonage， which led to tap water contamination and poisoning. The sense of responsibility and standardized management of enterprises are suggested to be strengthened. The water pipe network for production should be separated from that of domestic water and non-return valves should be installed at key locations to avoid similar poisoning events.

Abstract:Objective To provide reference for the disposition and clinical treatment of poisoning incidents， rapid toxin screening and the clinical symptoms and treatment of a case of Gymnopilus dilepis poisoning were conducted and discussed.Methods Ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry was used to detect the remaining poisonous mushroom in the contaminated food. Based on an epidemiological investigation， case data were collected. The results of the epidemiological investigation and the liver and kidney indexes of the patients were analyzed.Results Psilocybin and muscarine were detected in the Gymnopilus dilepis consumed by the patients. The symptoms were similar to those of psilocybin and muscarine poisoning， which included hallucinations， nausea， vomiting， abdominal pain， and diarrhea. The liver and kidney functions were normal.Conclusion The poisoning event was caused by psilocybin and muscarine in Gymnopilus dilepis.

Abstract:Objective To provide the basis for formulating relevant prevention and control measures， the etiological characteristics of foodborne diarrhea cases in Anhui Province from 2017 to 2021 were analyzed.Methods This cross-sectional study method was conducted from 2017 to 2021 and included data from diarrhea cases in 22 foodborne disease etiology-monitoring hospitals， Anhui Province. Anal swabs or feces were taken from all cases of diarrhea and the samples were tested for etiology as required. Data were processed with χ² _trend test or χ² trend test.Results A total of 15 484 specimens were collected from 2017 to 2021， and the total detection rate of pathogens was 23.75% （3 678/15 484）. The detection rate of Norovirus， Salmonella， diarrheagenic Escherichia coli， Vibrio parahaemolyticus， and Shigella were 10.01% （1 550/15 484）， 6.16% （954/15 484）， 6.10% （944/15 484）， 1.66% （257/15 484）， and 1.00% （155/15 484）， respectively. The detection rate of pathogens in different years （χ²_trend=11.249， P<0.05） and different quarters （χ²_trend=146.119， P<0.05） had statistical significance. Among all age groups， the pathogen detection rate of patients under 11 years old was the highest （30.29%， 1 123/3 708）. The pathogen detection rate of students was higher. The top three foods with suspected exposure were meat and its products （17.62%， 648/3 678）， grain and its products （15.17%， 558/3 678）， and multiple foods （13.78%， 507/3 678）. The site with largest number of suspected exposure cases was the household （69.93%， 2 572/3 678）.Conclusion The primary pathogenic bacteria of foodborne diarrhea cases in Anhui province were Norovirus and Salmonella and the total detection rate increased quarter by quarter. The major suspected exposed foods and places were meat and its products and households， respectively. Different foodborne disease prevention and control measures need to be developed for different populations， quarters， exposed foods， and places.

Abstract:Objective To analyze an acute gastroenteritis outbreak caused by co-infection with Vibrio parahaemolyticus （V. parahaemolyticus） and non-O1/O139 Vibrio cholerae （V. cholerae）.Methods Four anal swabs， 12 food samples， and 8 environmental samples enriched in liquid culture media were subjected to pathogen screening with real-time PCR. V. parahaemolyticus and V. cholerae strains isolated were subjected to whole genome sequencing， and virulence and antibiotic resistance genes were screened. Cladograms were constructed based on core genome single nucleotide polymorphisms.Results V. parahaemolyticus strains were detected in anal swab samples with real-time PCR that were toxR_VP+/tdh+/trh-， and two of them were positive for V. cholerae. The positive rate of V. parahaemolyticus in the anal swab samples was 100% （4/4）， the isolates were toxR_VP+/tdh+/trh-， and their serotype was O4：KUT. The positive rate of V. cholerae culture in the anal swabs of patients was 50% （2/4）. The serogroup of the isolates was non-O1/O139， and one of them was toxR_VC+/ctx/t3ss+. The positive rate of V. parahaemolyticus in the food samples was 66.67% （8/12）， and that in the environment samples was 12.50% （1/8）. The strains isolated from food and environmental samples were toxR_VP+/tdh-/trh-. The positive rate of V. cholerae culture in the food samples was 25.00% （3/12） and the isolated strains were toxR_VC+/ctx/t3ss-. The V. parahaemolyticus strains isolated from patient， food， and environment samples formed 10 distinct lineages. The four patient isolates were highly clonal. The V. cholerae strains isolated from two patients and three food samples formed five distinct lineages.Conclusion The outbreak was caused by co-infection with V. parahaemolyticus and non-O1/O139 V. cholerae. Real-time PCR and whole-genome sequence analysis of strains should be performed in the detection and analysis of outbreaks caused by vibrio co-infection. Additionally， optimization of vibrio culture pathways is recommended.

Abstract:Alternaria toxin， a secondary metabolite produced by Alternaria， is widely found in food products all over the world and poses a crucial threat to human health. Therefore， the analysis of toxicity and the search for prevention and control measures of the toxin， have become the focus of current research. This study mainly summarizes the toxicity， exposure risk， pollution control， and toxicity intervention methods of four common Alternaria toxins. It provides chain spore mold toxin risk assessment， safety evaluation standards， and a reference for the establishment of prevention and control measures to ensure food safety and preserve human health.

Abstract:As a common foodborne pathogen， Escherichia coli （E. coli） O157：H7 can cause serious diseases in human body at low infectious doses. Lateral flow chromatographic assay （LFCA） can meet the requirement of detecting E. coli O157：H7 in food samples rapidly due to its efficient separation property. At present， the widely-used LFCA methods generate weak signal strength and possess low detection sensitivity， which can hardly detect low concentration of E. coli O157：H7. Therefore， this review focuses on the newly published LFCA literature， and a systematic induction is performed concerning the detection efficiency and sensitivity of the above studies. The advantages and disadvantages of each method are compared in this review， which will provide important conclusive guidance for the development of LFCA in E. coli O157：H7 detection.