Abstract:Objective To study the antimicrobial resistance and virulence mechanism of two foodborne CTX-M-55 type extended-spectrum β-lactamase (ESBL)-producing Escherichia coli strains based on whole genome sequences. MethodsThe antimicrobial susceptibility testing of two CTX-M-55 type ESBL-producing Escherichia coli isolates (EC001 and EC002) that were collected from foodborne pathogen surveillance system in 2011 was conducted by antimicrobial susceptibility test and PCR. Then two strains were sequenced using the Illunima Hiseq 2000 platform. Based on the assembled genome sequences of two strains, the annotation of sequence type, plasmid replicon type, serotype, and antimicrobial resistance/virulence genes was performed using BioNumerics software. Results The two strains were identified to be ESBL-producing and fluoroquinolone-resistant. The genomic analysis result showed that strains EC001 and EC002 were ST21 and ST342, respectively, and serotyped to be enteropathogenic Escherichia coli (EPEC) O119∶H8. The plasmid of EC001 belonged to 5 incompatible groups includingIncFII, IncX1, IncY, Col156, and IncI2, and that of EC002 belonged to 2 incompatible groups including IncFII and IncX1. Notably, both strains harbored 2 types of ESBL-encoding genes blaCTX-M-55 and blaTEM-141. Additionally, the multi-antimicrobial resistance genes sul2/3, tet(A)(B), dfrA12, strA/B, aph(3′)-IIa, cml/cmlA1, floR, and oqxA/B were identified on the genome of strain EC001, while fosA and qnrS1 were identified on the genome of strain EC002. Compared with the genome of Escherichia coli K12_1655, two mutations were found at the 83^th (S83L) and 87^th (D87H) codons of gyrA, and one mutation was found at the 80^th (S80I) codon of parC in QRDRs of strain EC001. Noteworthy, 3 mutations were found at the 73^th (D73Y), 185^th (M185T) and 225^th (S225T) codons of pmrE in the chromosome of strain EC001, which might be responsible for its resistance to colistin. The virulence gene prediction result showed that both strains harbored classical locus of enterocyte and effacement (LEE) genes esc, esp, eaeA and tir, while EC001 contained iss gene which could increase serum survival capacity of this bacterium. Conclusion To our best knowledge, we applied whole genome sequencing in annotation of the resistance and virulence mechanism of two CTX-M-55-type ESBL-producing Escherichia coli strains in China. The data in this study will shed light on antimicrobial resistance and virulence mechanisms of Escherichia coli,and finally help prevent and control the contamination of this foodborne pathogen.

Abstract:Objective The four pathogens isolated from two outbreaks caused by fermented corn flour products in Yunnan Province were identified by recA partial sequence analysis. Methods The four isolates were already identified as Burkholderia spp. on the basis of 16S rRNA sequence analysis. They were amplified by recA specific primers in polymerase chain reaction together with Burkholderia gladioli (CICC 10574). The products were sequenced. The sequences were blasted with 73 species in Burkholderia genus and a phylogenetic tree was constructed. Results Comparative analysis of genetic relationship of recA gene could identify and classify the 73 species of Burkholderia, even subspecies of B.gladioli. Conclusion The four isolates from food poisoning cases could be identified as B.gladioli by recA sequence analysis. Their sequences were different from those of plant pathogens of B.gladioli with specific single nucleotide polymorphism(SNP), and was identified as Burkholderia gladioli pv.cocovenenans.

Abstract:Objective To investigate the distribution of Salmonella serotypes in food and feed from the import and export of Beijing port during 2004 to 2012. Methods In this study, 65 Salmonella strains isolated from food and feed were identified. The serotyping was performed with 13 reference strains. Results Four Salmonella isolate strains could not be identified to the serovar. The rest of 61 Salmonella isolated strains belonged to 9 serovars and 38 serotypes. The group B and group C1 were the major serovas. The ratio was 29.2%(19/65) and 26.2%(17/65) respectively. Salmonella agona and Salmonella enteritidis took the proportion of 10.8%(7/65)and 3.1%(2/65)respectively. It was the first time a strain of Salmonella stratford was detected in this laboratory. Conclusion There was a variety of serogroups and serotypes of Salmonella in the import and export food and feed from Beijing port. Salmonella serotypes surveillance was important for control and prevention of the foodborne disease in the region.

Abstract:Objective To study the molecular biological characteristics of food poisoning Salmonella isolates, and analyze the homology and resistance relationship between strains, which could provide scientific basis for prevention and control of foodborne disease and clinical treatment. Methods Totally 40 strains of Salmonella isolates were tested for susceptibility and molecular typing by pulsed field electrophoresis (PFGE). BioNumeries software was used to analyze the epidemiological relationships between strains. Results All the strains could be divided into 11 types by Xba I enzyme digestion, and drug sensitivity showed multiple drug resistance. Conclusion Foodborne Salmonella was highly sporadic and multidrug resistant was found in this region. The resistance of Salmonella was obvious, especially predominance serum enteritis, which suggested that it was necessary to strengthen the surveillance of Salmonella resistance.

Abstract:Objective To prepare the quality control materials (QCMs) of mercury, arsenic in marine fish and implement the proficiency test in the centers for disease control and prevention that are responsible for national food safety risk monitoring. Methods Sixteen species of marine fish were collected from Guangdong Province and the total mercury and arsenic in these samples were determined using direct mercury analyzer (DMA) and inductively coupled plasma mass spectrometry (ICP-MS) respectively. Epinephelus lanceolatus was selected to prepare the QCMs, which was cultivated in deep sea cages. The procedure of preparing QCMs included freeze mincing the muscle, drying, degreasing, comminution and seal package. One way ANOVA was used for evaluating the homogeneity of QCMs, and t test for the stability. ResultsThe experimental result showed that the Epinephelus oanceolutus QCMs remained well homogeneous and stable. The QCMs were used for proficiency testing which 193 laboratories had taken part in, the satisfactory performance rates of total mercury and arsenic were 81.1% and 80.2% respectively. DMA for mercury determination and ICP-MS for arsenic determination were the most efficient method. Conclusion The fish powder QCMs were suitable for total mercury, arsenic in food proficiency testing. This research provide method ology reference for both preparation of seafood based QCMs and edition of national food safety standard.

Abstract:Objective To suggest the further studies on complementary food supplements interventions in China on infants aged 6-24 months. Methods By review of studies on complementary food supplements intervention and comparison of nutrient composition in these studies with recommendation by WHO/FAO. Results Complementary food fortification in China such as food supplements is composed of protein, calcium, zinc, vitamin A, D, B₁,B₂ with its amount within WHO/FAO recommendation limit. Conclusion Program of complementary food fortification in China is effective for nutrition promotion in high-risk regions of China, but a comprehensive strategy incorporating with epidemiology and statistics is essential to reduce undernutrition.

Abstract:Objective To establish a method for the determination of pesticide residues in health food made from Chinese herbal medicines by dispersive solid phase extraction and dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry. Methods The samples were ultrasonic extracted by acetonitrile containing 0.5% formic acid. The supernatant was purified by dispersive solid phase extraction (d-SPE) extraction tube with anhydrous magnesium sulfate, N-propyl ethylenediamine (PSA) and C18, and then the target compounds were extracted and concentrated by the method of dispersive liquid-liquid microextraction (DLLME). Results Under optimal conditions, the linear range was 0.05-1.00 μg/ml, the linear correlation coefficient was above 0.999, the limit of detection was 0.3-3.0 μg/kg, the average recoveries of 29 kinds of pesticides were between 70.3% and 107.5%, and the relative standard deviation was less than 10%. Conclusion The method was simple, rapid, accurate and sensitive, and it could be used for the detection of organophosphorus pesticide residues in health food made from Chinese herbal medicines.

Abstract:Objective To establish a method for the determination of 4-chlorophenoxyacetic acid, 2,4-dichlor-ophenoxyacetic acid, naphthylacetic acid, indole acetic acid and indolybutyric acid in fruits by QuEChERS with gas chromatography-tandem mass spectrometry (GC-MS/MS). Methods Five plant growth regulators in fruits were extracted by methylene chloride, purified by QuEChERS, and were identified and quantified by GC-MS/MS after derivatization from the purified samples. Results The linear correlation coefficients of each linear regression equation for the five plant growth regulators were over 0.999 and the relative standard deviations (n=6) were between 0.480% and 14.8%. The recoveries of the method were between 63.4% and 107% at the spiked levels of 10.0-200 μg/kg. Conclusion The method was rapid and accurate, and could meet the requirement for the detection of the five kinds of plant growth regulators in fruits.

Abstract:Objective Two sample pretreatment method for the effective extraction and purification of rhodamine B in chili oil were investigated in detail. Valuable information for the accurate assay of rhodamine B by ultra-high performance liquid chromatography with fluorescence detection (UPLC-FLR) was provided. Methods The chili oil was extracted with acidified acetonitrile and then purified by a mixed type cation exchange solid phase extraction (SPE) column in the first method. In the second method, n-hexane containing 20% acetone was used to extract rhodamine B. The extraction was then purified by a neutral alumina SPE column. Both of the purified sample solution was blown to nearly dryness, re-dissolved in 50% methanol-water, filtrated and then analyzed by UPLC-FLR. Results The recoveries at three spiked levels (5.0,0.0,0.0 μg/kg, respectively) were in the ranges of 82.8%-101.9% and 80.8%-93.6%, with relative standard deviations ranging from 1.5%-2.9% (n=6) and 1.0%-2.1% (n=6), respectively. Conclusion Both of the two pretreatment method could meet the requirements of accurate determination of rhodamine B in chili oil. However, the recoveries at spiked levels (5.0 and 50.0 μg/kg) of the first method were higher than those of the second method. Furthermore, no large capacity SPE column was needed. There was no significant difference between recoveries of the two method at high spiked level (200.0 μg/kg).

Abstract:Objective To extract paralytic shellfish poisoning (PSP) with Supelco ENVI-Carb cartridge, develop a high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method for determination of PSP in bivalves aquatic products, and provide proof for the detection of PSP in aquatic products. Methods PSP was extracted by 1% acetic acid solution, supernatant added with ammonia (pH=4.0) was loaded on Supelco ENVI-Carb cartridge, and the eluent was dried up. Then the sample was separated on a TSK-GEL Amide column (2.0 mm×250 mm, 5 μm) with water contained 2 mmol/L ammonium formate-50 mmol/L formic acid and 95% acetonitrile contained 2 mmol/L ammonium formate-50 mmol/L formic acid was mobile phase for gradient elution. Detection was carried out by multiple reaction monitoring. Results PSP had a good linear result in the range of 8.1-705.0 μg/kg with detection limit of 10-35 μg/kg in bivalves aquatic products. The recovery was 47.0%-91.3%. Conclusion This method had good performance of extraction and with low matrix inhibition effect. The assay was suitable for trace detection of paralytic shellfish poisoning in bivalves aquatic products.

Abstract:Objective For implementation of labeling regulations, an event-specific real-time polymerase chain reaction(PCR) method for the detection of genetically modified AquAdvantage salmon was established in this study. Methods Primers and TaqMan probe were designed based on the event-specific sequence of AquAdvantage salmon. The specificity, sensitivity and repeatability of the developed method were examined, respectively. Results The specificity test of this method showed it was specific to AquAdvantage salmon. The 600 000-60 copies range showed a good linear relationship with Ct values, and its linear regression equation was y=-3.2194x+40.805(R²=0.997). The limit of quantification(LOQ) was 60 copies and the repeatability was good. Conclusion This event-specific real-time PCR method was suitable for the identification of genetically modified AquAdvantage salmon.

Abstract:Objective To establish a method for the determination of three mercury speciation in fish samples by liquid chromatogram-inductively coupled plasma mass spectrometry (LC-ICP-MS) with ultrasound-assisted acid extraction procedure. Methods The sample was extracted with acid under ultrasonic condition. The extraction efficiency of different hydrochloric acid concentration was tested and compared. The chromatographic separation conditions and the operation parameters of ICP-MS were optimized. Results The content of three species in fish samples was determined. Relative standard deviations were less than 5%. The recoveries were in the range of 82%-99%. The detection limit was 6.2 μg/kg. Conclusion The result indicated that the method was accurate, sensitive, simple, stable and was suitable for the determination of trace mercury speciation in fish.

Abstract:Objective To investigate the migration of 2,4,6-triamino-1,3,5-triazine and formaldehyde from melamine food container. Methods Samples which were collected from markets in Shanghai were identified and categorized using infrared spectroscopy. Then the migration of2,4,6-triamino-1,3,5-triazine and formaldehyde were tested referring to GB 4806.7-2016 and GB 31604.1-2015. Results Labelling of some samples were absent, incomplete or even incorrect. The migration amounts of formaldehyde from food container made of urea-formaldehyde resin were much higher than that of melamine. Conclusion Due to the high risk caused by migration of formaldehyde from urea-formaldehyde resin, methods should be established to identify different kind of resin of which the food containers were made.

Abstract:China is promoting the modern state governance system and governance capability comprehensively. The governance of food safety is changing profoundly. The idea of cooperative governance will embedded in all social participants related with food safety. Only by enhancing the functional transformation of the governments, strengthening self-discipline of enterprises, mobilizing the participation and supervision of the society and establishing effective institutional safeguards, the cooperative governance could be achieved.

Abstract:Objective To monitor the contamination rate and concentration of Norovirus in mussels sold in Beijing seafood market and to provide basic data for risk assessment of Norovirus in mussels. Methods The visceral mass of mussels were dissected and homogenized, Norovirus were extracted from visceral mass by adding PBS buffer and shaking 60 min. The Norovirus RNA was extracted and detected using commercial kit. Results Two hundred and ninety-three mussels samples were detected. The total positive rate was 9.22%(27/293). In all the positive samples, the gene group I accounted for 37.04% (10/27) and gene group II accounted for 62.96% (17/27). The range of the quantity of Norovirus in positive mussels was 6.20×10³-3.15×10⁵ gene copies/g (visceral mass). Conclusion The mussels sold in Beijing were contaminated by Norovirus.

Abstract:Objective To investigate the current situation of aerobic plate count, Staphylococcus aureus and β-lactamas in raw milk in Xinxiang. Methods Twenty-nine samples and 1 mixed sample of raw milk from 2 of 3 large-scale diary farms were separately collected once a month lasting for a year. The aerobic plate count and S.aureus were determined according to the current national food safety standard, meanwhile β-lactamas was identified by colloidal gold method. Results The median of aerobic plate count (CFU/ml) of raw milk from 3 farms was 13 000,4 450 and 130 000 respectively, all significantly lower than the limit of 2×10⁶CFU/ml in GB 19301-2010 (P＜0.01). Significant difference existed between the 3 farms(P＜0.05). When comparing with the mixed sample, the significant difference was only found in one farm (P＜0.05). The aerobic plate count changed seasonally which was higher in July and August. S.aureus contamination rates of the 3 farms were 1.1%(4/360), 16.7%(30/180)and 0.0%(0/180), respectively, with the range of 50-42 000 CFU/ml. β-lactamas could be detected in raw milk from all three farms, and the positive rate was 6.1%-10.6%. Conclusion The limit of aerobic plate count of raw milk in GB 19301-2010 was much higher than the actual level in Xinxiang. It is recommended to revise the standard limit value. There was a certain degree of S.aureus contamination in raw milk in one of the farms, and supervision should be strengthened. Furthermore, identification of the source of β-lactamas was needed, the research on the detection method of β-lactamase should also be strengthened.

Abstract:Objective To investigate the actual production and usage of food contact adhesives in China, review the main safety risks, and provide pertinent suggestions on safety management. Methods The production and usage information of food contact adhesives was investigated by questionnaires through typical enterprises. Relevant standards, regulations and safety management models on adhesives of other countries were collected, and analyzed. Results Materials permitted to use in adhesives couldn't meet the requirement of the industry. High risks of adhesives were occurred from various materials in different adhesives, limited awareness on safety management of some enterprises, and the absence of relevant risk management measures. Conclusion The safety standard of adhesives should be established quickly. An adhesive monomer list, limiting indexes of different adhesives, and safety control measures such as information transfer mechanism and functional barrier were recommended for the standard.

Abstract:Objective To evaluate the quality of enterprise food safety standards for aquatic products in Zhejiang Province, analyze the problems and reasons, and put forward countermeasures to serve for the government and enterprises. Methods Three hundred and twenty-five pieces of enterprise food safety standards from Zhejiang Province health administrative department were randomly sampled for assessment which covered from June 2009 to December 2015,0 samples each year and 25 samples for 2009. Results A total of 24 839 enterprise standards were received, 6 210 were for aquatic products (25.00%). Zhoushan, Ningbo, Wenzhou and Taizhou accounted for 61.13% (3 796/6 210). It was found that from the quality assessment of safety indicators, the compliance rate of pathogens was generally higher than that of pollutants. The compliance rate was increasing year by year. The compliance rate of lead limit was 83.69% (272/325), that for methyl mercury and inorganic arsenic were >95.00%, and was 79.69% (259/325) for cadmium. Except for benzo[a]pyrene, the compliance rate of different production were different, and the difference was statistically significant (P<0.05), the compliance rate of instant aquatic products in inorganic arsenic, N-dimethylnitrosamine and polychlorinated biphenyls were highest, the prefabricate aquatic and other products in lead, methylmercury, chromium, N-dimethylnitrosamine and polychlorinated biphenyls were the lowest. Conclusion It needs to further improve the awareness of food safety and food standards by the enterprises, strengthen the trainings and improve the knowledge on food standards.

Abstract:Objective To characterize the occurrence of Enterobacteriaceae and Cronobacter spp. in the powdered infant formula factories with dry-mix process, and study the potential contamination routes of Cronobacter spp. Methods Raw materials, intermediate products, end products, and environment samples from four factories were surveyed. Enterobacteriaceae and Cronobacter spp. were detected using traditional culture method. The isolates of Cronobacter spp. were profiled by pulsed-field gel electrophoresis(PFGE). Results The occurrence rate of Enterobacteriaceae was about 20% for the samples from the ground, air conditioning outlet and used cleaning tools. The occurrence rates of Cronobacter spp.were 2.56%(12/468)and 0.27%(6/2 185)from the product related samples and environmental samples in cleaning work area respectively. Clonal analysis using PFGE divided 22 Cronobacter spp. isolates into 13 patterns, each clone was unique to each factory and only four patterns were homologous respectively. The main source of Cronobacter spp. in end products was raw material, followed by environmental colonization strains. Conclusion It would help to get the distribution of Enterobacteriaceae and Cronobacter spp. in the powdered infant formula factories, identify the potential sources of Cronobacter spp. in the end products, develop sanitary control measures of the production process and ensure the end product safety.

Abstract:Objective In order to provide data for the formulation of maximum residue limitsassess (MRL) in wolfberry, the pesticide residues and the cumulative risk of pyrethroid were studied. Methods Three hundred and thirty-two kinds of pesticides including 15 pyrethroids in 40 samples which collected from different place were determined. Acute and chronic cumulative risk assessment were calculated by using hazard index approach. Results This method was appropriate to determine the pyrethroid residues in wolfberry by validation of the method. The result showed that the detecion rate of 4 pyrethroids was over 25%, including cypermethrin, fenvalerate, enpropathrin and cyhalothrin. The acute and chronic cumulative risk of pyrethroids in wolfberry was 0.497 and 0.016. Conclusion The cumulative exposure of 4 pyrethroids in wolfberry was small, but continuous monitoring should be maintained because of its high detection rate, and MRL also should be considered.

Abstract:Objective To investigate a foodborne illness outbreak in S restaurant and identify the pathogenic factors in order to prevent the occurrence of similar incidents. Methods According to established case definition, active case search and interview was implemented. Descriptive epidemiology was used to address epidemiologic characteristics, case-control study was conducted to analyze the risk factors, and samples were collected for testing as well. Results 162 cases was identified from the banquets, with the attack rate of 22.2% (162/730). The major clinic symptoms were diarrhea (100%, 162/162), stomachache (96.3%, 156/162), asthenia (77.2%, 125/162), nausea (68.5%, 111/162) and vomiting (53.1%, 86/162). The average incubation period was 12 hours. According to the result of case-control study, eating scallop (OR=1.74,5%CI:1.00-3.02) and calf ribs (OR=2.87,5%CI:1.38-5.99) was a risk factor. Samples from 34 patients, turtle pieces and cutting board were tested positive for Vibrio parahaemolyticus. Conclusion The main cause of this foodborne illness outbreak accident was due to Vibrio parahaemolyticus contamination, combined with cross contamination and undercooked food. It was necessary to standardize the operation procedures, strengthen the self-regulation of restaurants and consciousness to prevent such cases.