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ObjectiveThe pathogenic potential of Shiga toxin-producing Escherichia coli （STEC） isolated from different sources in China was classified to provide reference for risk management of STEC.MethodsThis study used hazard classification method，porposed by the Food and Agriculture Organization of the United Nations and the World Health Organization’s report， what name is Shiga toxin-producing Escherichia coli （STEC） and food： attribution， characterization and monitoring. We used to classify and analyze the published STEC data in China from 2018 to 2022.ResultsSTEC isolates were classified as low-risk （72.9%）， high-hazard （26.0%） and highest-hazard （1.1%） strains. The high-hazard strains were mainly from cattle or beef food （95.3%）， only 8 highest hazard strains were from cattle and patients.ConclusionThe serotypes of STEC strains are not enough to evaluate the virulence of STEC strains. The virulence gene combination is a more reliable method to classify the risk of STEC infection. This method could provide reference for STEC surveillance and risk assessment in China.

ObjectiveTo investigate the impact of edible vegetable varieties， temperatures， and inoculation sites on the survival of Listeria monocytogenes （L. monocytogenes）， providing a theoretical foundation for risk assessment and key control measures of L. monocytogenes in edible vegetables.MethodsFreeze-dried quantitative L. monocytogenes served as the strain source， with the surfaces and sections of five edible vegetables （colored pepper， onion， cucumber， virgin fruit and lettuce） used as inoculation sites. The strain was cultured at both 4 ℃ and 25 ℃ for 7 days. Regular monitoring of the L. monocytogenes quantity in each sample was conducted， and growth was analyzed.ResultsThe quantity of L. monocytogenes freeze-dried in different bottles was uniform （F=1.923， P

ObjectiveThe aim of this study was to detect botulinum toxin and Clostridium botulinum （C.botulinum） in 30 batches of infant formula milk powder obtained from an enterprise and to analyze the whole genome of the strain of C. botulinum type B isolated from the samples.MethodsThe samples were subjected to C. botulinum isolation and botulinum toxin typing experiments according to the “National standard for food safety microbiological examination of C. botulinum and botulinum toxin” （GB 4789.12—2016）. The whole genomes of the isolated strains were sequenced and their genetic characteristics were analyzed.ResultsBotulinum toxin was not detected in any of the 30 batches of samples. After intraperitoneal injection of the enrichment solution into mice， four batches of milk powder samples induced symptoms of botulism， but C. botulinum was isolated from only one batch of milk powder samples. Genome sequencing revealed that the bacterium was C. botulinum group Ⅰ， type B， the toxin gene cluster was type Ha， and the toxin gene was subtype B2.ConclusionThe detection of C. botulinum in infant formula milk powder with a complex background of microorganisms should not be based on the isolation of bacteria as the gold standard but should be confirmed by a mouse toxicity test of the enrichment solution combined with a botulinum toxin antiserum protection test. Whole genome sequencing can accurately identify strains and analyze relevant genetic characteristics， providing reliable technical support for handling poisoning events.

ObjectiveThis study aimed to develop ready-to-use standard strains of Salmonella typhimurium （S. typhimurium） TA97， TA98， TA100， and TA102 for mutagenicity testing.MethodsFreeze-dried strains of S. typhimurium TA97， TA98， TA100， and TA102 at both high and low concentrations were quantified. The spontaneous reversion rate of the freeze-dried strains after 3， 5， 7， and 18 h was measured. Homogeneity， storage and transportation stability， spontaneous revertant frequency， and mutagenic agent mutation rate of the ready-to-use standard strains were evaluated following the CNAS-GL003 2018 “Guidelines for the Evaluation of Homogeneity and Stability of Proficiency Testing Samples” and GB 15193.4—2014 “National Food Safety Standard - Bacterial Reverse Mutation Test.” Standard deviations of spontaneous revertant frequency and mutagenic agent mutation rate test results between 20 ready-to-use standard strains and fresh strains were compared.ResultsHigh-concentration lyophilized samples had concentrations ranging from 107-108 CFU/sample， while low-concentration samples had concentrations ranging from 105-106 CFU/sample. The spontaneous reversion rate results after 18 h of incubation met the requirements of GB 15193.4—2014. Homogeneity results for the four ready-to-use standard strains showed F-values of 1.12， 1.05， 1.68， and 1.38， with F < F0.05 （19，20）， meeting CNAS-GL003 requirements. The detection results for the four freeze-dried strains stored at 25 ℃ for 5 d， 4 ℃ for 14 d， and -20 ℃ for 6 months met storage and transportation stability requirements. The standard deviation of spontaneous revertant frequency in the 20 ready-to-use freeze-dried standard strains was smaller than that of fresh strains.ConclusionThe ready-to-use standard strains developed in this study exhibit excellent homogeneity， storage， and transportation stability. Moreover， the stability of spontaneous revertant frequency in the ready-to-use freeze-dried standard strains surpasses that of fresh strains.

ObjectiveTo provide technical support for combating adulteration of plant-derived ingredients， the detection application of non-directional screening of plant-derived ingredients in food was realized.MethodsModified CTAB， SDS， and kit methods were used to extract genomic DNA from various plant-derived foods. Quality， concentration， and purity of the obtained DNA were compared. Using the RbcL gene in the chloroplast genome of plants as a barcode， 30 plant species were selected to verify the universality and specificity of this primer. Combining the second-generation high-throughput sequencing with DNA barcode technology， species identification of four mixed plant samples sold in Shandong Province was performed.ResultsDNA extraction using the improved CTAB and kit methods removed the interference of polysaccharides and polyphenols， which was an ideal effect， whereas that of the SDS method was poor. The DNA concentration obtained by CTAB method was higher than that obtained using the kit method. This method had a good performance in universality and specificity of 30 selected plant species. At the genus and species level， the identification rate of plant species in mixed samples was high. The detection rate at the species level was 98%， and resulted in non-target matching.ConclusionThe RbcL gene can be used as a barcode for plant species identification. The discrimination rate is high at the genus level. At the species level， detection rate was high and discrimination rate was low. To provide a foundation for the advancement of DNA metabarcoding method in the field of identification for plant-derived components in food， the method can be further improved by increasing the barcode length.

ObjectiveTo explore the maximum allowable concentration of six chemical reagents and three enzyme lysates in a polymerase chain reaction （PCR） amplification system and the differences of IGEPAL CA-630 cleaving different species.MethodsPrepare different kinds of working solutions， including six chemical reagents （IGEPAL CA-630， CTAB， SDS， EDTA， guanidine isothiocyanate， and NaOH） and three enzymes （lysozyme， lysostaphin， and protease K） with different concentrations. Add the working solutions to the fluorescent quantitative PCR system and then analyze the differences in Ct values. Streptococcus thermophilus， Staphylococcus aureus， and Escherichia coli were lysed with IGEPAL CA-630 solutions （1% and 0.1% with TE buffer）， TE buffer and deionized water， respectively， and the differences in PCR results were analyzed.ResultsIn the PCR system， the maximum allowable final concentrations of IGEPAL CA-630， CTAB， SDS， EDTA， guanidine isothiocyanate， and NaOH were 0.800‰， 0.256‰， 0.012 8‰， 0.8 mmol/L， 0.012 8 mol/L， and 0.64 mmol/L respectively. The maximum allowable concentrations of lysozyme， lysostaphin， and protease K were 0.512， 1.28， and 0.512 μg/mL. In the lysing of S. thermophilus and S. aureus with IGEPAL CA-630， the Ct values of TE solution， 0.1% and 1% IGEPAL CA-630 decreased successively， with no significant difference between the TE solution and deionized water. There was no significant difference in Ct values of E. coli treated with deionized water， TE solution， 0.1% and 1% IGEPAL CA-630.ConclusionThis study established the maximum allowable concentration of the above nine components in the PCR amplification solution. Additionally， it was found that increasing the concentration of IGEPAL CA-630 could enhance DNA extraction from gram-positive bacteria.

ObjectiveTo prepare proficiency testing samples of Vibrio parahemolyticus （V. parahemolyticus）and apply to laboratory test.MethodsThe five background strains and V. parahemolyticus were identified by biochemical reaction and matrix-assisted laser desorption ionization time of flight mass spectrometry（MALDI-TOF MS）. The V. parahemolyticus positive samples and negative samples were prepared by freeze-drying. The negative samples contained background bacteria only and the V. parahemolyticus were added in positive samples with background strains. Twenty samples were selected randomly for uniformity test. The samples were stored respectively at -20 ℃ and 4 ℃ to evaluate the storage stability， meanwhile the transport stability were evaluated by storing samples at 25 ℃ and 37 ℃ for 7 d. Samples were distributed to laboratories participating in the proficiency test with operation instruction， and the feedback results from laboratories were analyzed.ResultsThe results of all the related strains were consistent with the expectations. Both of the positive samples and negative samples could meet the requirements of the uniformity and stabilit. The satisfaction rates of assessment results were 87.5% and 90% in 2019 and 2020 respectively.ConclusionThe V. parahemolyticus samples could meet the requirements of the proficiency test. By organization proficiency test， the difference of laboratories can be discovered which is helpful to further improve the laboratory test capacity.

ObjectiveThe purpose of this study was to provide basis for the revision of GB 4789.28—2013 and the quality control of culture media by screening the quality control strains of culture media for salmonella test.MethodsThe strains specified in GB 4789.28 and 9 salmonella strains（Salmonella newport， salmonclla Infantis， Salmonella choleraesuis， Salmonella blegdam， Salmonella kottbus， Salmonella arizona， Salmonella dublin， Salmonella agona， Salmonella. anatis） isolated from real food were used to test the growth rate and selectivity of 10 different brands of media including Rappaport Vassiliadis Salmonella Enrichment， Selenite Cystine Broth， Tetrathionate Broth Base enriched broth， Bismuth Sulfite Agar， Hektoen Enteric Agar， Xylose Lysine Desoxycholate Agar by quantitative and semi-quantitative methods. It was evaluated whether the quality control strain used in GB4789.28—2013 could meet the quality control of salmonella media.ResultsThe results showed that the growth rate and selectivity of different media brands were different when the same strain was used， and Salmonella choleraesuis and Salmonella arizonae had higher requirements on the quality of media.ConclusionIt is suggested that medium production enterprises and microbiology laboratories should use strains isolated from food with higher quality requirement in medium testing， and the quality control methods should be highly standardized to ensure the stability and reliability of test data.

ObjectiveTo study the effects of the kind and concentration of antibiotics in pre-enrichment for the detection of Shiga toxin-producing Escherichia coli （STEC） in the current international standard method.MethodsThe minimal inhibitory concentrations （MICs） of three antimicrobials supplemented in an STEC enrichment broth of four official methods were measured through testing of a panel of STEC and non-STEC isolates.ResultsThere were differences among different antibiotics for the inhibition of STEC. At the recommended concentration， acriflavine and cefsulodin inhibited the growth of stx1a and stx2b subtypes of STEC， while novobiocin inhibited the growth of stx1a， stx1c， stx1d， stx2b， stx2d， stx2e， stx2f and stx2g subtypes of STEC. In addition， there was no significant difference among MICs of STEC and other gram-negative bacteria to acriflavine， cefsulodin and novobiocin （P>0.05）. MICs of gram-positive strains to three tested antimicrobials were significantly lower than those of gram-negative bacteria （P

ObjectiveTo prepare and evaluate Enterotoxigenic Escherichia coli（ETEC） reference.MethodsThe standard strain CMCC（B）43208 was identified by biochemical reaction， matrix-assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF MS） and gene sequencing. 600 ETEC reference samples with 103 CFU/sample were prepared by freeze-drying. 20 samples were selected randomly for uniformity test， and samples were tested transportation stability by simulating 25 and 37 ℃， and storage stability by stroing samples at -20 and 4 ℃. Three laboratories were organized for collaborative calibration. 20 kinds food were chosen as the substrates to evaluate the applicability. The strain CMCC（B）43208 was identified as Escherichia coli by all of biochemical reaction， MALDI-TOF MS and 16 s RNA gene sequencing， and was identified as ETEC by lt，stp and sth gene. The uniformity result was F=1.48

ObjectiveTo develop plasmid DNA reference materials that can be used for polymyxin antibiotic resistance encoding genes rapid detection.MethodsThe reference sequence of mcr­1， mcr­3 and mcr­5 were retrieved from the National Center for Biotechnology Information to construct recombinant plasmids and strains. The recombinant strains were subcultured for 15 generations to detect the genetic stability of the target gene. The recombinant plasmid was extracted and vacuum dried to prepare the standard sample. The limit of detection （LOD） of PCR and RT­qPCR was determined after the standard sample was hydrated and continuously diluted with 10­fold gradient， respectively. Multi­tube plasmid DNA standard samples were randomly selected to qualitatively and quantitatively evaluate the uniformity and storage stability at 4 ℃， 37 ℃ and -20 ℃ by PCR and UV spectrophotometer.ResultsFragments of mcr­1， mcr­3 and mcr­5 that encoding polymyxin resistance mechanism were successfully obtained. Target genes in the recombinant strains could stably inherited after subcultured for 15 generations. The LOD of PCR and RT­qPCR of mcr­1， mcr­3 and mcr­5 standard samples were 1.67×104 and 1.67 copies/μL， 1.31×104 and 13.1 copies/μL， 1.55×105 and 1.55 copies/μL， respectively. The mass F values of 12 standard samples randomly selected for each gene were all less than the F critical value， each gene could be detected by RT­qPCR and indicating that the uniformity of the samples met the requirements. When standard samples were stored at 4 ℃ for 90 d， 37 ℃ for 14 d and -20 ℃ for 360 d， the qualitative and quantitative test result showed it was stable without significant difference.ConclusionIn this study， plasmid DNA standard samples that carrying mcr­1， mcr­3 and mcr­5 were prepared. The target genes could be stably inherited， the standard samples had good uniformity and storage stability， and could be used as a quality control samples for polymyxin antibiotics resistance encoding genes detection and mechanisms prediction.

ObjectiveTo prepare proficiency testing samples of Cronobacter spp. and apply to laboratory test in 2018-2020.MethodsThe background bacteria and Cronobacter spp. were identified by biochemical reaction and MALDI-TOF MS. Cronobacter spp. negative samples (background bacteria only) and positive samples (background bacteria and Cronobacter spp.) were prepared by freeze-drying. 20 samples were selected randomly for uniformity test. The samples were stored respectively at -20 ℃ and 4 ℃ to evaluate the storage stability, at 25 ℃ and 37 ℃ for 7 d to evaluate the transport stability. Samples were distributed to laboratories participating in the proficiency with operation instruction, and the feedback result from laboratories were analyzed.ResultsThe identified result of all the related strains were correct. Both of positive samples and negative samples were uniform and stable. The satisfaction rates of assessment result were 97.1%, 94.7% and 100% respectively in 2018-2020.ConclusionThe samples could meet the requirements of proficiency test. By organization proficiency test, the difference of laboratories can be reflected which is helpful to further improve the laboratory test capability.

ObjectiveBased on the fact that the quality control bacteria used for bacterial drug sensitivity determination are commonly sensitive to antibiotics, while most foodborne pathogens isolated in China are relatively tolerant to these antibiotics, the concentration range of antibiotics used for antimicrobial sensitivity test is very wide, which resulting in antibiotic wastes and inaccurate test result.MethodsIn this study, five standard samples with clear minimum inhibitory concentration (MIC) were successfully developed for sensitivity test of common antibiotics(streptomycin, gentamicin, chloramphenicol, cefoxitin and ampicillin). Agar dilution and microbroth dilution method were respectively used to determine the susceptibility of isolates to the antibiotics, the reference strains were developed via vacuum freeze-drying.ResultsThe reference strains with clear MICs assignment of streptomycin, gentamicin, chloramphenicol, cefoxitin and ampicillin were developed respectively. The antibiotic susceptibility of the reference strains was genetically stable, and the uniform and storage stability of them were good. When stored at 37 ℃ for 13 d, 4 ℃ for 90 d and -80 ℃ for 360 d, respectively, the viable bacteria number basically remained above 105 CFU/vial. All confirmed antibiotic resistance phenotypes could be detected, and the MICs value of the certain antibiotics did not show apparent fluctuation or drift.ConclusionThe development of reference strains that in line with the characteristics of drug resistance of foodborne pathogens in China with clear MICs assignment to certain antibiotics would help to enrich the types of reference strains in China, and further strengthen the monitoring of drug-resistant bacteria to ensure food safety and public health.

ObjectiveTo satisfy the demands of laboratory quality control and proficiency testing for the detection of enteroinvasive Escherichia coli (EIEC), a stable EIEC reference material was developed with independent intellectual property rights, good stability and clear background genomic information.MethodsNGS Technique was used to sequence the whole genome of enteroinvasive Escherichia coli (CMCC 44840), bioinformatics analysis was performed to identify the species, serotype, MLST type and virulence genes; EIEC lyophilized samples with 103 CFU were prepared by freeze-drying method ; The homogeneity test was performed according to CNAS-GL017, and the result were statistically analyzed by one-way ANOVA; The samples were stored at -20, 4, 25 and 37 ℃, respectively, and their storage stability and transport stability were evaluated; Five kinds of food matrix samples were used to verify the applicability of reference materials, and three laboratories were organized for collaborative calibration.ResultsThe genome size of CMCC 44840 was 4.96 Mb, the GC content was 50.7%, and the genome contained 5424 coding genes. This strain was identified as the species of Escherichia coli, and the serotype and the MLST type were predicted to be O28ac: H7 and ST311, respectively, and it carried ipaH, virB, virF and other virulence genes. The homogeneity test result of the EIEC lyophilized sample was F=1.79, which met the homogeneity requirements of reference materials. The EIEC samples were still 103 CFU when storing at -20 ℃ and 4 ℃ for 60 d and storing at 25 ℃ and 4 ℃ for 7 d, and decreased on the third day at 37 ℃. EIEC were detected in 20 different food matrix samples with EIEC lyophilized samples after enrichment. The samples were 103 CFU determined by three collaborative calibration laboratories, and there were no significant differences among these laboratories (F=0.59).ConclusionThe EIEC reference material prepared in this study has clear genome sequence information. The homogeneity and stability meet the requirements and have good applicability, which can meet the requirements of quality control and capability verification in food testing laboratory.

ObjectiveCombined the traditional isolation culture, ITS sequencing and metagenomics sequencing technology to establish a new method for the analysis of fungal community composition and species diversity in Pu'er tea at retail markets.MethodsPu'er tea samples were collected at retail markets and tested for cultivable fungi in accordance with "National food safety standard Food microbiological examination: Counting of Molds and Yeasts" (GB 4789.15—2016), and the isolated strains were sequenced by ITS and analyzed in the NCBI database; the fungal genomic DNA from Pu'er tea samples was extracted by CTAB method, and performed PCR amplification and amplicon sequencing; high-throughput sequencing data was used to build OTUs clustering, and carried out species composition and diversity analysis.ResultsTwelve fungi were isolated and cultured from Pu'er tea samples, mainly Aspergillus and Lichtheimia, of which Aspergillus niger had the highest proportion (25%, 3/12). The result of species distribution based on metagenomics showed that the diversity and uniformity of fungal species in Pu'er tea samples were low, and there were relatively high number of dominant species; the highest proportion of fungi was Ascomycota (74.03%), and at the genus level, the fungi in Pu'er tea were dominated by Blastobotrys (49.43%) while Aspergillus accounted for a relatively low percentage (14.04%).ConclusionThis study comprehensively applied traditional isolation culture, molecular biology and high-throughput metagenomics sequencing technology to establish a new method for the analysis of fungal community composition and species diversity in Pu'er tea at retail markets. It provided ideas and references for further research on the microbial community structure in Pu'er tea and its impacts on quality and safety.

ObjectiveTo investigate the culture effect of MRS AGAR medium of 5 domestic brands and 2 imported brands on lactic acid bacteria, and to compare the product quality.MethodsUsing spiral coating counting method, the growth of 3 strains of lactobacillus specified in GB 4789.28—2013 and 9 strains of non-national standard Lactobacillus (including standard strains and laboratory isolated strains) on the different MRS AGAR medium were quantitatively determined. By comparing the growth rate of different brands of medium to different strains, the quality of each brand of medium was evaluated.ResultsThere were significant differences in the growth rate of GB 4789.28 standard strain on different brands of MRS AGAR media, and some of the medium had quality problems. Streptococcus thermophilus ST-21 isolated from probiotics powder had good growth ability in reference medium, and there were significant differences in growth rate among different brands of MRS AGAR medium.ConclusionThe result of this study indicated that there are great differences in the quality of MRS AGAR media of different brands at home and abroad; Streptococcus thermophilus S-T21 can effectively evaluate the quality difference of different brands of media, and is suitable for the quality control of MRS AGAR media.

ObjectiveAmino acids, vitamins and inorganic salts were used to replace beef extract and peptone to develop a selective medium with controllable quality for Salmonella.MethodsEffects of 20 kinds of amino acids, 11 kinds of vitamins or 4 kinds of inorganic salts on the growth characteristics of Escherichia coli ATCC 25922 were studied, and the optimal concentration was determined. The beef extract and peptone in bismuth sulfite (BS) agar or Hektoen Enteric (HE) agar were replaced, and the chemically defined BS agar or HE agar was developed.ResultsAdding asparagine, aspartic acid, valine, thiamine hydrochloride or riboflavin to the basic medium was the most favorable for the growth of Escherichia coli ATCC 25922, and the OD595 were all higher than 0.1. However, adding serine, lysine hydrochloride, isoleucine, nicotinic acid, biotin or disodium hydrogen phosphate to the basic medium did not promote the proliferation of Escherichia coli, and the OD595 was almost 0. The chemically defined BS agar or HE agar was prepared by replacing beef extract, peptone with 35 kinds of nutrients according to the optimal concentration. After verification of quality control strains, chemically defined BS agar or HE agar was similar to commercial medium in cell growth index, colony morphology and special color reaction.ConclusionChemically defined BS agar or HE agar meet the quality requirements of national standard.

ObjectiveTo prepare Cronobacter spp. (Enterobacter sakazakii) proficiency test samples which meet the requirements of uniformity and stability, and use them for proficiency test.MethodsThe background strains and Cronobacter. spp were identified by biochemical and matrix-assisted laser desorption ionization time of flight mass spectrometry method. Freeze-drying was used to prepare the samples with 104CFU/bottle. According to Guidance on Evaluating the Homogeneity and Stability of Samples Used for Proficiency Testing, 20 samples were selected randomly for uniformity test. The samples were stored at -20 and 4 ℃ respectively to evaluate the storage stability, and at 25 and 37 ℃ to evaluate the transport stability. According to GB 4789.40—2016, samples were distributed to participating laboratories with operation instruction, and then the feedback result were analyzed.ResultsThe identified result of all the related strains were correct and consistent with expectations. The result of uniformity and stability tests met relevant requirements. All of the experiment result submitted by 25 laboratories within the required time were correct, and the satisfaction rate was 100%.ConclusionThe samples of Cronobacter spp. Enterobacter sakazakii in milk powder proficiency test can meet the relevant requirements, and this proficiency test provides external quality control assessment result for the participating labratories simultaneously.

Coastal cities are vulnerable to increasing flood risks caused by the combination of sea-level rise (SLR) and storm tides (STs), due to their low-lying topography and densely distributed assets. Faced with this challenge, comprehensive and integrated flood risk information is vital and fundamental for the planning, implementation and optimization of coastal risk adaptation and management. The goal of this study is to propose an integrated assessment approach to sea-level rise- and storm tide-induced flood risks on a coastal urban system by employing a wide range of indicators across ecological, physical and socio-economic dimensions. To demonstrate its applicability, a case study of Xiamen City, China was performed. The results show that this approach is applicable for assessing the specific flood risks on urban ecological, physical and socio-economic system, respectively. Under 4.75 ∼ 5.86 m extreme sea-level, 11 600 ∼ 17 100 ha land and 440 000 ∼ 720 000 population will be flooded in Xiamen City, with flood risks—measured by monetary—of 858 ∼ 1134 million, 4744 ∼ 10 590 million and 2537 ∼ 4175 million RMB of ecological, physical and economic systems, respectively. Coastal ecosystem will suffer flood risks on ecological services, mainly regulation service; and wetland is the dominant ecosystem that will be affected, which imply urgent needs to wetland conservation. Indirect risk on economy accounts for a large proportion of total risks, and should be given adequate weight in the decision-making process.

Objective Campylobacter species are the main causes of foodborne illness worldwide, posing significant threats to public health. This study aimed to investigate the antibiotic resistance and genomic characterization of C. jejuni/C.coli from retail chickens in Beijing. Methods Antimicrobial susceptibility testing was conducted on 126 C. jejuni/C. coli isolated from retail chickens in Beijing, following CLSI protocols. Whole genomes of all isolates were sequenced using the Illumina platform. Results More C. coli (83.82%) showed multi-drug resistance than C. jejuni (8.62%). Genomic analysis demonstrated 42 sequence types (STs) and 12 clonal complexes (CCs), from which CC828 and CC52 were dominant. cdtA, cdtB and cdtC encoding cytotoxic protein were present spontaneously in most C. jejuni but not found in any C. coli isolates. The abundances of antibiotic resistance genes (ARGs) and virulence genes (VGs) in C. jejuni and C. coli were significantly different, with ARGs numbered in C. coli and VGs in C. jejuni. Conclusions High prevalence of multi-drug resistance C. coli and C. jejuni isolated from Beijing chickens were challenging clinical antibiotic usages in the treatment of Campylobacter infection. The surveillance of particular C. jejuni and C. coli STs correlated with higher resistance and virulence needs to be strengthened in the future. [ABSTRACT FROM AUTHOR]