| With the abuse of antibiotics,Escherichia coli,a food-borne pathogen with serious harm,is increasing the drug resistance,and its multi-drug resistance spectrum is gradually widening.Broilers,one of main carriers of Escherichia coli could easily transmit the pathogen to human body through the food chain during slaughtering and processing.Therefore,it is particularly important to explore the pollution of Escherichia coli in the processing and production chain of poultry slaughterhouses.In this study,the samples were collected at a large poultry slaughterhouse in Zhejiang Province.The pollution indicators of air-sinking microorganisms were detected and assessd for the level of microbial contamination in different areas of the slaughterhouse.The isolated Escherichia coli were examined for their virulence genes,and their drug resistance was evaluated.Finally,the phylogenetic relationship of the isolates was investigated by ERIC-PCR typing.(1)In this experiment,the external and internal air-depositing microorganisms of the slaughterhouse plant were separated to detect their pollution indicators.The flora structure diversity was then analyzed by the Illumina high-throughput sequencing method of 16 S rRNA V3-V4.The results showed that the total number of colonies,Enterobacteriaceae,mold and yeast would be increasing in the eight workshops after slaughter.The total number of colonies in slaughtering reached a maximum of 1100 cfu/dish,and the number of Enterobacteriaceae in scalding and dehairng was a maximum of 1500 cfu/dish.The number of molds and yeasts in slaughtering were respectivly up to 175 cfu/dish and 50 cfu/dish.Comparing the structure of the air-precipitating bacterial flora inside and outside the slaughterhouse,from the level of the phylum,the dominant phylum in the interior of the slaughterhouse and the outside of the slaughterhouse were the same,including the Firmicute,Actinobacteria and Proteobacteria.From the level of the genus,the dominant genus in the interior of the slaughterhouse were different from the outside of the slaughterhouse.There was bacterial contamination of different genus types.The leading bacterium in the internal air of the slaughterhouse were Staphylococcus,Escherichia,Pseudomonas,and the main dominant genus in the outside air of the slaughterhouse was Bacillus,Phycicoccus,Kocuria.(2)In the experiment,water was collected to cultivate the microorgan isms from the slaughterhouse,and the wiped ground and instrument surfaces of each area with sterile gauze.Then,the 16 S rRNA V3-V4 Illumina high-throughput sequencing method was used to analyze the bacterial structure diversity,and 9 kinds of 24 drug resistance genes of bacteria were detected by PCR.The results showed that Proteobacteria,Firmicutes and Actinobacteria were the predominant phyla in the water and on the surface of floor and slaughtering equipment in the different areas of the slaughterhouse,and their relative abundance were 45.18%~87.74%,0.09%~33.46%,3.34%~28.09%,respectively.The dominant genera included Acinetobacter,Streptococcus,Enhydrobacter,Dermacoccus,Pseudomonas,Flavobacterium,Tetragenococcus,Chryseobacterium and Arcobacter,accounting for 46% of the total taxa.The detection rate of sul?,sul,qnrS,blaTEM and aadA1 was 100%,and that of floR,tetA and ereA was 88.9%.(3)In the experiment,240 samples were collected from the abattoir airprecipitating microorganisms,water bodies,ground,instrument surfaces and chilled chickens.Escherichia coli strains were isolated from these samples,and their virulence genes were tested to assess their resistance.The detection results of Escherichia coli resistance genes indicated that the detection rate of ESBL-type Escherichia coli derived from cold fresh chicken was the highest.Escherichia coli was most resistant to ampicillin(62.0%)and sulfamethoxazole(55.4%),and 33(35.9%)were multi-drug resistant strains,against up to 7 types of antibiotics.Except that penicillin gene(mecC)and polymyxin gene(mcr-1)were not detected,the detection rates of drug resistance genes pmrA(92.4%),blaTEM(78.3%)and qnrS(53.3%)were higher.In addition,the virulence gene test showed that the detection rate of enterotoxin-producing Escherichia coli(ETEC)virulence gene was the highest,reaching 31.5%.The detection rate of virulence genes in the Escherichia coli from air was the highest,and four virulence genes were detected,including stx,est,elt and aggR.(4)In this experiment,ERIC-PCR typing analysis was performed on 92 strains of Escherichia coli isolates.The results showed that at the level of similarity coefficient of 0.80,Escherichia coli isolates from poultry slaughterhouses of different origins could be classified into 11 s trains(A~H).Among them,there were 32 strains of type E,which were dominant bacteria types.This type of bacteria come from different samples of chicken anal swabs,chilled chickens of hanging district,surface of hanger in eviscerating district and air in pre-cooling district.It could be seen that Escherichia coli was crosscontaminated between the air,water,equipment,ground and chilled chicken in the same slaughterhouse. |
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