Isolation And Identification Of Potential Pathogenic Bacteria From Pigs In A Slaughterhouse And Analysis Of Their Biological Characteristics

Food security is a fundamental livelihood issue in our country.As an important part of food,animal-derived food must be strictly quarantined during processing to ensure its quality and safety.During the slaughter process,animals are polluted by environmental pollution or the carcass carrying pathogenic bacteria,which not only pose a threat to food security,but also affect public sanitation.Objective:To investigate the situation of slaughtered pigs contaminated by Escherichia coli,Salmonella,Pasteurella,and Bordetella in a pig slaughterhouse in Xinjiang and analyze and detect the potential threats of pathogenic bacteria to public health,food security and the development of animal husbandry.Scientific and reasonable suggestions are put forward for the problems existing in the slaughtering process of slaughterhouse,and provide a strong guarantee for animality food security.Methods:180 nasopharynx swabs of slaughtered pigs were collected to extract pasteurella and Bordetella,and 180 swabs of slaughtered pigs were collected to extract Escherichia coli and Salmonella.Escherichia coli,Salmonella,Pasteurella multocida and Bordetella were extracted and cultured in selective medium and identified by morphological observation and biochemical test.PCR technique was used to further identify and detect the drug resistance genes and virulence genes of the four pathogenic bacteria.Combined with animal pathogenicity test and drug sensitivity test,drug resistance and virulence were analyzed.Results:22 strains of Escherichia coli were extracted,the extraction rate was12.22%(22/180),7 strains of salmonella were 3.89%(7/180),1 strain of Pasteurella multocida was 0.56%(1/180),and 2 strains of Bordetella were 1.11%(2/180).Escherichia coli and Bordetella have a high proportion of resistance to antibiotics,which is 36.67%and 46.43%respectively,while salmonella and Pasteurella multocida are more sensitive to antibiotics,which are 45.24%and 36.36%respectively.The five drug resistance genes detected in Escherichia coli were tetB,TEM,ermB,Sul2 and floR.The detection rate was 45.46%(5/11);The three drug resistance genes detected in Salmonella were sul II,tetG and aadA1,the detection rate was 27.27%(3/11);The six drug resistance genes detected in Pasteurella multocida were oxA-1,ermA,tetA,dfrA5,sul1 and sul3,the detection rate was 54.55%(6/11);The two drug resistance genes detected by Bordetella were tet B and CTXM,the detection rate was 50.00%(2/4).The two virulence genes detected by Escherichia coli were iutA and fyuA,the detection rate was 22.22%(2/9);The 14 virulence genes detected in Salmonella were spvB,spiA,pagC,msgA,sipB,prgH,spaN,orgA,tolC,sitC,lpfC,sifA,sopB and pefA,the detection rate was 93.33%(14/15);The 13 virulence genes detected by Pasteurella multocida were ptfA,pfhA,sodA,sodC,tbpA,nanB,nanH,ompA,PlpB,PmHAS,exbB,tonB and hgbA,the detection rate was 86.67%(13/15);The two virulence genes detected by Bordetella were DNT and flaB,and its detection rate was66.67%(2/3).The median lethal doses of Escherichia coli,Salmonella,Pasteurella multocida and Bordetella in mice were 10^9.33,10^9.27,10^8.68and 10^9.03,respectively.Conclusion:The detection of Salmonella,Pasteurella and Bordetella from the swabs of live pigs in the slaughterhouse and pig carcass swab after slaughter indicates that there are certain food security hazards in the pork on the market,and the slaughter and processing environment should be improved.It is recommended that slaughterhouses should quarantine pigs sent for slaughter based on"Pig Slaughter and Quarantine Regulations"in our country.