Abstract:Objective To explore the effects of sodium chloride and tryptone in the components of mannitol salt agar on the quality of mannitol salt agar， and investigate the product quality of 5 domestic brands and 1 imported brand of mannitol salt agar sold on the market.Methods The effects of sodium chloride and tryptone with different brands and concentrations of sodium chloride and tryptone on the quality of mannitol salt agar were investigated using plate coating counting and semi quantitative scoring method. Quantitative determination of the growth of different types of Staphylococcus aureus and Escherichia coli on 5 domestic brands and 1 imported brand of mannitol salt agar. Referring to GB 4789.28—2013， the growth rate， growth index， and colony size of different brands of culture media for different strains were compared， and the quality of each brand of culture media was evaluated.Results There were significant differences in the growth rate and growth index of experimental strains on mannitol salt agar prepared with different types and concentrations of sodium chloride or tryptone. The growth index of non target bacteria in different brands of mannitol salt agar was qualified， but there were significant differences in the growth rate and colony size of the target bacteria.Conclusion Sodium chloride and tryptone have a significant impact on the quality of mannitol salt agar， which directly determines whether the medium is qualified. There are significant differences in the quality of different brands of mannitol salt agar sold domestically and internationally， and the quality of domestic mannitol salt agar is better than that of imported medium.

Abstract:Objective To study the effect and possible mechanism of Panax ginseng fructus juice concentrate on immune injury induced by cyclophosphamide in mice.Methods Seventy-two specific pathogen-free （SPF） C57BL/6J male mice were randomly divided into six groups （12 per group）， including blank group， cyclophosphamide group， positive drug group， low-， middle- and high-dose Panax ginseng fructus juice concentrate groups （83， 166， 249 mg/kg）. From day 1 to day 14， mice in three groups of Panax ginseng fructus juice concentrate were intragastrically administrated with concentrate at volumes of corresponding dosage， and mice in blank group and cyclophosphamide group were gavaged with the same amount of distilled water. Mice in positive drug group were also intragastrically administrated with the same amount of water from day 1 to day 7， and then from day 8 to day 14， gavaged with 20 mg/kg levamisole hydrochloride （LH）. From day 12 to day 14， mice in cyclophosphamide group， positive drug group and three Panax ginseng fructus juice concentrate groups were intraperitoneally injected with 80 mg/kg cyclophosphamide， while those in blank group were injected with the same amount of normal saline. At the end of the experiment， the spleen index was calculated， leukocyte （WBC）， lymphocyte （LYM） and LYM% in peripheral blood were measured， and the activities of lactate dehydrogenase （LDH） and acid phosphatase （ACP） in serum and spleen， activities of superoxide dismutase （SOD）， catalase （CAT） and malondialdehyde （MDA） content in spleen homogenate were measured.Results There was no significant difference in body weight among groups （P>0.05）. Compared with blank group， the spleen index of mice decreased （P<0.01）， WBC， LYM and LYM% decreased， the activity of ACP in serum and spleen of mice decreased or showed a downward trend， the activity of SOD and CAT in spleen decreased and the content of MDA increased in cyclophosphamide group（P<0.05）. Compared with cyclophosphamide group， spleen index of mice in the panax ginseng fructus juice concentrate groups increased （P<0.05， P<0.01）， LYM% in the low- and high-dose panax ginseng fruit juice concentrate groups increased， activity of ACP increased or showed an upward trend in the panax ginseng fructus juice concentrate groups， activities of SOD and CAT showed an increasing trend in the low-dose group of panax ginseng fructus juice concentrate， and contents of MDA decreased in all three groups of panax ginseng fructus juice concentrate （P<0.05， P<0.01）.Conclusion To some extent， panax ginseng fructus juice concentrate can improve the immune injury induced by cyclophosphamide in mice， which may be related to its effect of reducing oxidative damage of the immune organs in mice.

Abstract:Objective To ensure the accuracy of the results in such products， the uncertainty of the aerobic plate count in the plant-derived foods was evaluated.Methods In accordance with the national standards for food safety GB 4789.2—2022， the aerobic plate count in plant-derived foods was determined by plate count agar medium and test sheets. The introduced uncertainty components in the experiments were evaluated until the synthetic uncertainties of the aerobic plate count in the plant-derived foods on plate count agar medium and test sheets were calculated respectively.Results As the confidence probability was 95%， the extended uncertainties of the aerobic plate count in the plant-derived foods on plate counte agar medium and test sheets were 0.045 863 and 0.049 436， respectively. And the confidence intervals of the measurement result were 7.0×10³-1.1×10⁴ and 7.0×10³-1.2×10⁴ CFU/g.Conclusion The uncertainties of the aerobic plate count in the plant-derived foods on plate count agar medium and test sheets have no significant difference between them. According to the evaluation data， the results of the test samples can be judged and analyzed. It is suggested to improve in-house detection ability to reduce the introduction of uncertainty. It will provide strong technical support to production， inspection and supervision of the plant-derived foods.

Abstract:Objective To lay the foundation of quickly and effectively response to such epidemics for laboratories， the detection of the real-time PCR and culture test results of stool and anal swab samples from 3 outbreaks caused by Campylobacter was compared.Methods Biological samples from the 3 outbreaks of Campylobacter were collected. Bacterial culture was performed on the samples using filter culture method. DNA was extracted from the original samples， 24 h enriched samples and 48 h enriched samples. Kappa test was used to analyze the results of real-time PCR and culture method.Results The real-time PCR detection sensitivity of original samples， 24 h enriched samples and 48 h enriched samples were 90.91%， 97.22% and 100%. And the detection specificity were 75.00%， 84.00%和78.95%， respectively. Kappa value for the consistency analysis in culture method with real-time PCR based on original samples， 24 h enriched culture samples and 48 h enriched samples were 0.643， 0.813 and 0.785， respectively.Conclusion The combination of real-time PCR detection and culture detection is an effective laboratory testing method for the respond of Campylobacter outbreaks.

Abstract:Objective A method for the detection of cyanide in vegetables and edible fungi by distillation-flow injection method was established.Methods Innovative pretreatment method， the use of water vapor distillation technology to process the sample to effectively remove interfering impurities， and then the use of continuous flow syringe to detect the cyanide content in the distillate.Results 20 samples were tested for cyanide， the detection limit of the method was 0.012 5 mg/kg，the lowest quantitative concentration was 0.037 5 mg/kg；The recovery rate was between 97.0%-103.6%；The relative standard deviation RSD （n=6） was 3.74%-4.56%.The method was compared with isonicotinic acid-pyrazolone Spectrophotometer and isonicotinic acid-barbituric acid Spectrophotometer.Conclusion The results of distillation-flow injection method was accurate and reliable，with good repeatability and the test time was shortened. It was suitable for rapid and accurate detection of cyanide in large quantities of vegetables and edible fungi.

Abstract:Objective To understand the situation of Gardenia consumption in Chinese residents and to assess the geniposide exposure level and health risk of the Gardenia consumption population in China.Methods Data on geniposide content in Gardenia jasminoides in China were collected through literature search and special monitoring， incorporating data from the 2019-2022 survey on consumption of food and drug substances in China， and the simple distribution method and probability assessment method were used to obtain the geniposide exposure level and health risk of different populations in China through the consumption of Gardenia jasminoides.Results The consumption rate of gardenia in 9 provinces of China was 10.32%， and the mean value of consumption was 0.36 g，and daily Geniposide consumption of 1.48 g for high consumers Simple distribution assessment showed that the mean exposure of geniposide of the edible population of Gardenia in 9 provinces was 0.29 mg/kg·BW， Exposure to geniposide in high consumers （P95） was 1.28 mg/kg·BW， Among the Gardenia consuming population in 9 provinces， 17.20% of the residents were exposed to geniposide through Gardenia consumption exceeding their tolerable daily intake （TDI， 0.386 mg/kg·BW） of Gardenia glycosides. The daily average exposure of the edible population in He’nan Province was the highest 0.54 mg/kg·BW. The results of the probabilistic assessment showed that 14.70 % of the Gardenia consuming population in China had geniposide exposure exceeding the TDI， posing a potential health risk.Conclusion The risk of exposure to geniposide in China’s Gardenia consuming population is generally low， but there is a health risk in some high consuming population （P95）.

Abstract:Objective To provide scientific basis for the safety of vegetables in Qingdao， the pollution level of pesticide residues in vegetables in Qingdao was understood.Methods Six hundred and eighty vegetable samples of 7 categories were randomly collected from 10 districts and cities in Qingdao from 2020 to 2022. The characteristics of 28 pesticide residues in vegetable samples were detected and analyzed， and the acute and chronic dietary exposure risks of detected pesticides were assessed.Results In 680 vegetable samples， the detection rate was 9.71% （66/680）. The over-standard rate was 2.79% （19/680）. A total of 10 pesticides were detected， and the highest detection rate was bifenthrin with （4.50%， 27/600）. A total of 6 pesticides exceeded the standard， and the highest rate was chlorpyrifos （1.18%， 8/680）. The difference between the detection rate and the over-standard rate of all kinds of pesticides was statistically significant （P<0.001）. There was significant difference in the detection rate among the 7 types of vegetables （P<0.001）， and the detection rate of pesticide residues was the highest （27.68%， 31/112）， and the number of pesticide residues was the highest （8 kinds）. The distribution of prohibited pesticides was found in all the 7 types of vegetables. Agricultural residues were detected in 10 districts and cities， except Huangdao district， Jiaozhou city and Pingdu city. The detection rate was 19.44% （7/36） in Chengyang district and 7.02% （4/57） in Licang district. The number of pesticide residues detected in Shibei district was up to 7. After acute and chronic dietary exposure risk assessment， aHQ and cHQ were all less than 1.Conclusion Some prohibited pesticides were still detected in vegetable samples sold in Qingdao， but the pesticide residue level was low， and the health risk of agricultural residue in vegetables ingested by residents through dietary channels is small. It was necessary to continue to strengthen the supervision and management of prohibited pesticides to minimize the risk of pesticide residues in edible vegetables to human health.

Abstract:Objective To analyze the pollution status and exposure risks of heavy metals by three edible traditional Chinese herbal medicine， such as ganoderma lucidum， dendrobium officinale， and American ginseng in Guangdong Province.Methods Fresh and dried raw materials of Ganoderma lucidum， Dendrobium officinale， and Panax quinquefolium， as well as food products， were collected from 10 cities in Guangdong Province. Among them， 33 samples were collected in Guangzhou， and 30 samples were collected in each of the other 9 cities. The concentrations of lead， cadmium， total mercury， and total arsenic in the three substances were determined and analyzed using inductively coupled plasma method. Based on the point assessment model， we calculated the average concentrations of heavy metals in fresh （converted at a dry rate） and dried raw materials， and evaluated the health risks according to the medicinal and dietary consumption patterns.Results As the dietary consumption pattern， the exposure levels were higher than the medical consumption pattern， and the cadmium exposure levels of Ganoderma lucidum， Dendrobium officinale and American ginseng accounted for 8.51%， 8.72% and 8.56% of PTMI. The exposure levels of total mercury accounted for 3.51%， 0.91%， and 1.08% of PTWI. The MOE values of lead exposure were 11.56， 7.14， and 20.94， respectively， while the MOE values of total arsenic exposure were 68.34， 102.39， and 152.28， respectively. After considering the dietary exposure pathway， the risks of heavy metal caused by the three edible traditional Chinese herbal medicine were still within an acceptable range.Conclusion Residents in Guangdong Province had a lower risks of exposure to lead， cadmium， total mercury， and total arsenic through the dietary exposure pattern of ganoderma lucidum， dendrobium officinale， and panax quinquefolium.

Abstract:Objective To investigate the pollution status of heavy metal contamination in commercially available grains in Wuxi， and to access the potential risk to humans.Methods The grains such as rice， flour and coarse cereals sold in Wuxi were collected， and the contents of Pb、Cd、Hg、As were detected according to the national standard method. The single factor pollution index and Nemero multi-pollution index were used to evaluate the pollution status of heavy metals in grains， and the environmental health risk assessment model recommended by the U.S. Environmental Protection Agency （US EPA） was used to evaluate the health risk caused by heavy metals through diet.Results The single factor Pollution Indexs of rice， flour and coarse cereals were all less than 0.6， which is within the safe range. The carcinogenic risk value of grains is 1.71×10^-4， which is within the acceptable risk level recommended by US EPA， and rice is the major exposure media. The non carcinogenic hazard quotient （HQ） of all four metals were all less than 1，which were decreased in the order of As>Cd>Hg>Pb. All the non carcinogenic hazard index （HI） was less than 1 too， which were decreased in the order of rice> flour>coarse cereals.Conclusion The heavy metal contamination of grains in Wuxi is within the acceptable range， and the health risk assessment showed that carcinogenic risk value of grains was within the acceptable risk level recommended by US EPA. The main carcinogenic and noncarcinogenic risk all come from rice， and the attribution factor is arsenic.

Abstract:Objective In order to find out the contamination situation and potential risk of Listeria monocytogenes in refrigerated ready-to-eat prepackaged foods. This study carried out a quantitative contamination risk survey of L. monocytogenes for ready-to-eat cooked meat products with short shelf life.Methods We collected 64 samples of ready-to-eat cooked meat from Chengdu， and carried out qualitative and quantitative detection of L. monocytogenes according to traditional culture method and RT-PCR molecular detection method. Additionally， the second generation of the whole genome sequencing was performed after DNA extraction of the isolated strains， and relevant epidemiological characteristics were analyzed.Results The results showed that L. monocytogenes were isolated from 6 samples of cooked meat （6/64）. All 6 L. monocytogenes positive samples were produced by the same manufactory， of which 5 were three platters of marinated meat. The results of quantitative detection showed that the contamination level of L. monocytogenes in three platters of marinated meat was 30-200 CFU/g， and the contamination level of cooked pork samples with positive L. monocytogenes was lower as <10 CFU/g. Six isolates were identified as L. monocytogenes harboring LIPI-3 virulence island related genes by whole genome sequencing analysis. In silico MLST analysis found that the main ST types were ST3 （n=2） and ST121 （n=2）， followed by ST8 and ST9. Single nucleotide polymorphisms （SNP） results showed that 23 SNP difference was detected between L. monocytogenes strains LM22071911 and LM22080802， and 13 SNP differences were detected between L. monocytogenes strains LM22062706 and LM22080806. All four strains above were isolated from the same factory， indicating that there was a risk of direct transmission of two clonal groups of L. monocytogenes in the processing of the factory.Conclusion Some refrigerated ready-to-eat prepackaged foods sold in Chengdu are facing the contamination by L. monocytogenes， and it is necessary to strengthen the control in processing.

Abstract:Objective Clostridium sp. isolation， identification and analysis and toxin gene detection were carried out on 57 pieces of commercially available infant formula milk powder and 50 pieces of commercially available infant rice noodles sold in Beijing. The data of Clostridium sp. contamination level was obtained， and the identification methods were evaluated.Methods The isolates were comprehensively identified by their growth characteristics， Gram staining， morphological characteristics under ordinary microscopy， combined with the results of mass spectrometry identification， 16S rRNA gene sequencing and whole-genome sequencing （WGS）. The botulinum toxin genes of isolated Clostridium sp. were detected by PCR. Then， sequencing and comparative analysis of PCR positive fragments were carried out.Results Thirty-eight Clostridium sp. in 26 samples of the 57 commercially available infant formula milk powder samples were detected. More than two types of isolates were detected in 9 samples. Five Clostridium sp. were detected in 5 samples of 50 commercially available infant rice flour. PCR amplification of the Clostridium botulinum type E toxin gene of a Clostridium sphenoides was positive， the amplified fragment sequencing comparison results showed that this sequence was not an E-type Clostridium botulinum toxin gene， and the WGS results also confirmed it. There were no toxin genes of Clostridium botulinum in all the 43 isolates.Conclusion Identification of Clostridium sp. requires comprehensive analysis by multiple methods. The contamination of Clostridium sp. exists in commercial infant formula milk powder and infant formula rice flour. It is necessary to strengthen the monitoring of important Clostridium sp. in infant formula food to provide data support for risk assessment.

Abstract:Objective To analyze the distribution of Bacillus cereus （B. cereus） and vomiting toxin gene （ces） in cooked rice samples which simulated contaminated by raw vegetables， and provide basic data for prevention of food poisoning caused by B.cereus.Methods Fifty raw vegetable samples were collected in this study. Simulate method was as contaminated “freshly cooked rice” with 0.85% physiological saline solution from washing raw vegetables， and then place it in a 30 ℃ 70% RH environment for 24 h to prepare a sample of “contaminated rice”. Plate counting， real time PCR and digital PCR were performed for raw vegetable and “contaminated rice” samples. Statistical analysis was performed on the detection rates grouped by different vegetable types for raw vegetable samples and “contaminated rice” contaminated with them.Results The detection ratios of B.cereus， ces gene and Bac16s RNA gene in raw vegetables was 80.00% （40/50）， 0（0/50） and 10.00%（5/50）. The detection ratios of B.cereus， ces gene and Bac16s RNA gene in “contaminated rice” was 94.00% （47/50）， 14.00% （7/50） and 90.00% （45/50）. There was significant difference in the detection ratio of B.cereus between raw vegetables collected from agricultural markets and farmland（χ²=11.063， P=0.000 88 correction）， and the difference in the detection rates of Bac16s RNA gene and ces genes in “contaminated rice” contaminated with the two groups of raw vegetables mentioned above is statistically significant（χ²=3.926， P=0.047 5 correction； χ²=5.444， P=0.019 6 correction）. Seven “contaminated rice” were tested positive for the ces gene using real time PCR， with Ct values ranging from 24.12 to 37.73， and digital PCR results ranging from 6.8 copes/μL-6.2×10⁶ copes/μL.Conclusion Cooked rice samples which simulated contaminated by raw vegetables might be has the etiology characteristics that lead to a risk of food poisoning caused by B.cereus.

Abstract:Objective To analyze the distribution characteristics of virulence genes and drug resistance of foodborne Listeria monocytogenes （Lm） in Liaoning Province， 2020—2021.Methods The 19 virulence genes of Lm including 6 loci （prfA， plcA， plcB， hlyA， mpl and actA） and 10 loci of virulence island Ⅱ （inlA， inlB， inlC， inlD， inlE， inlF， inlG， inlH/C2， inlI and inlJ）， and the other 3 virulence related loci （iap， fbpA， hpt） were detected by PCR.Results Among 91 Lm strains， the detection rate of 19 virulence genes was 39.6%. All 19 virulence genes of 36 Lm strains were detected， and 55 Lm strains showed different deletions of two or more virulence genes. inlG and inlF were the most seriously deficient， with a deletion rate of 41.8%（38/91） and 52.7%（48/91）. According to the virulence gene deletion， 91 strains could be divided into 13 genotypes， and the dominant virulence genotype was type Ⅰ with all 19 virulence genes. The 91 Lm strains were divided into four PCR serotypes， namely， 1/2a （3a）， 1/2b （3b）， 1/2c （3c） and 4b （4d， 4e）， with the proportions of each serum 59.3% （54/91）， 34.1%（31/91）， 3.3% （3/91） and 3.3% （3/91）， respectively. The 3 strains of serotype 4b were all from meat and meat products.Conclusion The virulence gene carrying rate of foodborne Lm in Liaoning Province is high， and the virulence gene deletion has diversity and sample differences.

Abstract:Objective To investigate the dietary nutrition status of adolescent cyclists in Jiangsu Province during the training period from 2018 to 2021， and to clarify whether there is a problem of insufficient nutrient intake among adolescent cyclists during the training period， further provide evidence for relevant departments to take timely intervention measures.Methods A total of 1 100 adolescent cyclists in Jiangsu Province from 2018 to 2021 were selected as the survey subjects to investigate and analyze the dietary structure of adolescent athletes during training. A total of 1 086 valid questionnaires were returned.Results The actual energy intake of the 1 086 adolescent athletes basically reached more than 80% of the energy requirement （EER）； the energy provided by fat per day for adolescent athletes was lower than the recommended intake （25%-30%）， and the energy provided by carbohydrates per day was 64.72%， both within the recommended range （55%-65%）. There was insufficient water intake per day， and the average daily dietary fiber intake （10.23 g） was lower than the recommended amount （25-30 g）； except for male athletes， who have higher intake of niacin than the recommended amount， the intake of other vitamins is lower than the recommended amount. In terms of dietary structure， eggs， cereals and their products are well-intake， which can meet the recommended intake requirements， while livestock meat， dairy products， vegetables and beans are all insufficiently ingested， and fruit， potato， aquatic products， poultry and other foods are seriously insufficiently ingested. The energy supply ratio of breakfast and lunch is within the recommended intake range， but the energy supply ratio of dinner is higher.Conclusion There are insufficient intake of energy and nutrients in adolescent cyclists in Jiangsu Province， which cannot meet the needs of athletes during training. There is also an unreasonable dietary structure， with insufficient intake of livestock meat， dairy products， vegetables， beans， fruits， and aquatic products. At the same time， the long-term high intake of dinner is not conducive to the athletes’ own athletic ability and normal training. It is suggested that nutrition education for athletes， managers， and chefs should be strengthened， and the dietary structure of athletes should be appropriately adjusted to improve their dietary behavior and ensure their nutritional and health needs， laying the foundation for improving sports performance.

Abstract:Objective To establish and improve the food composition database of He’nan Province， the nutritional components of fish， shrimp， crab， and shellfish in He’nan province were analyzed.Methods The water， ash， protein， fat， carbohydrate， total nitrogen， carbohydrate， multivitamins， and essential minerals of fish and crab from restaurants and supermarkets from December 2017 to December 2020 were determined.Results The water and ash contents were basically the same. Carbohydrate was not detected except in fried food. The energy content of crab was higher than that of fish and shrimp. The energy， protein， total nitrogen， and fat contents of fried fish were higher than those of fresh fish. The total amount of fatty acids in fish， shrimp， crab， and shellfish was normal； EPA and DHA were the major components. The highest content of DHA was observed in squid （0.209 g/100 g）， pasha （0.181 g/100 g）， and cod （0.153 g/100 g）， and the highest content of EPA was observed in crab roe （1.07 g/100 g）， small yellow croaker （0.38 g/100 g）， and golden carp （0.297 g/100 g）. All the amino acids were detected in fish， 90% in shrimp， crab， and shellfish， and the content of amino acids in crab roe was higher.Conclusion Flavoring and cooking oil influenced the food composition in the cooking process of fish， shrimp， and crab products. The content of monounsaturated fatty acids was positively correlated with the total fat content in fresh fish. Fish and crab had higher contents of monounsaturated fatty acids， and shrimp had the recommended proportion.

Abstract:Objective To construct an evaluation index system for foodborne disease surveillance system in Beijing， and to provide reference foodborne disease system evaluation in Beijing.Methods Based on the actual situation of foodborne disease surveillance in Beijing， the evaluation index framework was established through literature search， and the Delphi method was applied to the index system for two rounds of expert consultation， and finally the three-level evaluation index system of foodborne disease surveillance system was established.Results The evaluation index system of foodborne disease surveillance system was divided into three levels， including 3 primary indexes， 24 secondary indexes and 94 tertiary indexes. The indexes are sorted by weight， and the primary indexes are the monitoring system structure and function （0.402 3）， the monitoring system operation guarantee （0.321 5）， and the monitoring system performance （0.276 2）. The top 3 secondary indexes were monitoring definition （0.065 0）， monitoring purpose （0.063 1） and monitoring content （0.059 3）. The top 3 third-level indexes were food-borne disease case definition （0.032 7）， food-borne cluster case definition （0.032 3） and active surveillance case definition （0.031 0）. The average score of importance of each index was 7.68 （5.62-9.18）， and the average coefficient of variation was 0.21 （0.11-0.39）.Conclusion The index system established in this study covers the structure and function of the surveillance system， monitoring performance and operation guarantee， etc. The research method is appropriate and the results are reliable， which has reference significance for the evaluation of foodborne disease surveillance system in other regions in the future.

Abstract:Objective To provide scientific basis for rational clinical use and traceability of outbreaks of foodborne Salmonellosis， the drug resistance and molecular typing characteristics of foodborne Salmonella in Ganzhou City was understood， and a database of drug resistance and molecular fingerprinting of foodborne Salmonella in Ganzhou City was established.Methods Serotyping， drug susceptibility testing， whole genome sequencing （WGS） and pulsed field gel electrophoresis （PFGE） were performed on 136 strains of Salmonella isolated from the active surveillance of foodborne diseases in Ganzhou City from 2020 to 2022. And drug resistance gene annotation and graphical clustering analysis were performed.Results The highest rate of foodborne Salmonella in Ganzhou City was found for STR resistance （83.09%）， followed by TET （78.68%） and AMP （76.47%）. Multi-drug resistant strains accounted for 76.47%， with a wide range of resistance spectrum types， and the main prevalent resistance spectrum type was AMP-TET-CHL-STR-SXT. WGS predicted a total of 61 resistance genes in 7 categories， with the highest rate of aminoglycoside resistance genes （99.19%） and the lowest rate of macrolides （8.87%）. 136 strains of Salmonella with S. typhimurium variant and S. typhimurium as the dominant serotype were classified into 98 band types by PFGE molecular typing.Conclusion Foodborne Salmonella in Ganzhou City has a serious drug resistance status， with a high rate of drug resistance gene carriage and diverse genotypes. The PFGE molecular type is polymorphic. The dominant serotype may cause outbreaks and epidemics， and surveillance and research should be strengthened.

Abstract:Objective To provide a genetic basis for scientific prevention and control of food poisoning caused by Bacillus cereus， the pathogenic characteristics of foodborne Bacillus cereus strains isolated in Yueyang City Hu’nan Province from 2014 to 2019 were understood.Methods The virulence genes hemolysin A （hblA） and phospholipase C （plc） were sequenced and amplified from 26 Bacillus cereus strains isolated from catering stores in Yueyang City from 2014 to 2019. Seqman and MEGA X software were used to analyze the nucleotide sequences of hblA and plc genes of Bacillus cereus.Results The homology between the coding product of genes hblA and plc of Bacillus cereus isolated from Yueyang City and corresponding Bacillus cereus protein sequences in GenBank were greater than 93.0%.Conclusion The hblA and plc genes of Bacillus cereus isolated from Yueyang City have high homology with Bacillus cereus gene sequences in GenBank， indicating relatively closer genetic relationship. This study lays the research foundation for further understanding and scientific prevention and control of food poisoning events caused by Bacillus cereus.

Abstract:Objective To provided reference for the disposal of similar incidents in the future， a food poisoning incident at a school in Changsha City was analyzed.Methods The epidemiologic characteristics of the incident was described， the suspicious food through case-control study was analyzed， food hygiene investigation and laboratory test to find pathogenic factors and contaminated food were conducted.Results A total of 54 suspected cases were found， and the clinical manifestations were mainly diarrhea （100%）， abdominal pain （92.59%） and fever （88.89%）. The incubation period of the disease was 2.5-51 h， with a median of 13 h. The case-control analysis showed that food sets of the Salt Crispy Chicken Shop between May 1 and 3， 2022 were suspected high-risk foods. Salmonella was detected in anal swab samples of 14 cases and 3 batches of food samples. The molecular typing analysis of the positive strains isolated by pulse gel electrophoresis showed that they came from the same source of infection and were all Braenderup type.Conclusion The incident was a food poisoning incident caused by Salmonella Braenderup infection， and the suspected food was boiled eggs. It is suggested that the Market Supervision Bureau should strengthen the supervision of restaurants， the restaurants should improve food hygienic knowledge and standardize the operation process.

Abstract:Objective To provide a basis for preventing and controlling such incidents， an investigation of a foodborne disease outbreak caused by Vibrio parahaemolyticus during a wedding banquet was conducted to identify pathogenic food，the pathogenic factors and the source of contamination.Methods An epidemiological investigation， on-site food hygiene investigation， and laboratory testing were used to analyze the cause of this event and take corresponding prevention and control measures.Results Twenty suspected cases were found. The main clinical manifestations were diarrhea， abdominal pain， fever and vomiting. The shortest incubation period was 4 h， the longest incubation period was 35.5 h， and the average incubation period was 16 h. Vibrio parahaemolyticus was detected in the samples of anal swab from 3 cases. Molecular typing analysis of the positive strains of Vibrio parahaemolyticus by pulsed field gel electrophoresis indicated that they were from the same source of infection. The case-control analysis found that the crispy salted hoof was the suspected poisoning food. Hygienic investigation showed that the crispy salted hoof after cooking shared the cutting board for rough processing raw seafood when they were cut into small pieces.Conclusion This incident is a foodborne disease outbreak of Vibrio parahaemolyticus caused by raw and cooked cooking utensils. It is suggested that catering units should strengthen food hygiene education， and label the raw and cooked tools to prevent cross contamination， and actively implement other food safety measures.

Abstract:Objective Since the global pandemic of coronavirus disease 2019 （COVID-19） broken， a series of local outbreaks caused by the contamination of imported cold chain food by SARS-CoV-2 had been reported in China’s Mainland. To provide corresponding suggestions for the prevention and control of similar epidemics in the future， the characteristics and spread of such epidemics was analyzed.Methods All the literature， official news reports and other materials on the local COVID-19 outbreak caused by SARS-CoV-2 contaminated imported cold chain food was collected， and the corresponding data was sort out and analyzed.Results From June 2020 to November 2022， a total of 20 local COVID-19 outbreaks related to imported cold chain products were reported， with a total of 1 646 cases， involving 9 provinces. Among the 20 outbreaks， there were 10 outbreaks in 2020， 3 outbreaks in 2021， and seven outbreaks in 2022， and 3 outbreaks had 200 or more cases.Conclusion Since the global pandemic of COVID-19 broken， the 20 local outbreaks related to imported cold-chain food traced domestically were caused by cold-chain workers who were infected by contact with imported cold-chain food or their overpacks， and most of local outbreaks （75%） caused subsequent community transmission. But under various effective control measures such as the construction of centralized supervision warehouses in China， the number and duration of local outbreaks related to imported cold chain food have shown a downward trend.

Abstract:In recent years， food poisoning caused by Listeria monocytogenes contamination in meat products at home and abroad has occurred frequently. Diseases caused by Listeria monocytogenes contamination have become a hidden danger to people’s health. As a traditional country in the production and consumption of meat products， China should be vigilant. Meat product manufacturers need to develop monitoring programs to prevent Listeria monocytogenes contamination and control potential risks. Based on the microbial characteristics of Listeria monocytogenes， the possible ways of contamination by Listeria monocytogenes in the production process of meat products are analyzed， and the monitoring and disinfection plan of Listeria monocytogenes in the production process of meat products is put forward， which provides direction and help for the risk control measures of meat product manufacturers.