| Escherichia coli contamination is an important problem in the production of poultry animal food.Risk control of Escherichia coli contamination during broiler slaughter is a key link to ensure food safety and public health.Firstly,in order to understand the distribution and prevalence of foodborne Escherichia coli in broiler slaughtering,the key risk points of Escherichia coli pollution control were analyzed by sampling chicken carcasses and environment in each slaughtering link.Secondly,in order to understand the drug resistance of Escherichia coli to antibiotics and disinfectants in broiler slaughter,the drug resistance and drug resistance gene carrying were analyzed by micro broth dilution method and high-throughput sequencing analysis technology,respectively.Finally,in order to contain the spread of drug-resistant Escherichia coli in broiler slaughtering,a safe and efficient organic acid disinfectant was screened out through quantitative germicidal test and organic interference test.The germicidal test of drug-resistant and sensitive Escherichia coli was carried out in lab,and the application evaluation test was carried out in broiler slaughterhouse.The results are as follows:Firstly,the chicken carcasses in the broiler slaughtering process were seriously contaminated by E.coli（68.4%）.The slaughtering processes with more serious contamination included split packaging（90%）,hair removal（87.5%）,broaching treatment（87.5%）and post-broaching cleaning（85%）.After pre-cooling and disinfection,the contamination rate of E.coli showed a downward trend（71.4%）,but the cross-contamination generated by split packaging increased the contamination rate of E.coli.Based on the survey results of E.coli pollution in each slaughtering link,it was determined that the key risk control links were dehairing,opening treatment,cleaning after opening and packaging segmentation.Secondly,the drug resistance of E.coli in broiler slaughter was serious.The MIC value of E.coli to antibiotics was determined by broth microdilution method.The results showed that the resistance rate to tetracycline（89.09%）and ampicillin（70.55%）was the highest,and most of them were multidrug resistant（74.1%）.The MIC values of Escherichia coli against disinfectants were determined by broth microdilution method.The results showed that Escherichia coli had resistance to benzalkonium chloride（100%）,cetylpyridine chloride（89.5%）and sodium hypochlorite（88%）.By the high-throughput sequencing analysis,it was found that the resistance genes encoding antimicrobial agents mainly included dfr A14（70.8%）,bla CTX-M-1（62.5%）,aph（3’’）-Ib（62.5%）,aph（6）-Id（62.5%）,and the resistance genes encoding disinfectant efflux pump mainly included qac（100%）,acr B（100%）,emr B（100%）.In addition to qac only effluxed disinfectant resistance genes,the other 18 efflux pump genes simultaneously effluxed disinfectant and antimicrobial drug-related resistance genes.The mdf A gene encodes the resistance of tetracycline and quaternary ammonium disinfectant.Thirdly,in this study,three kinds of organic acids which meet the national standards of food additives were selected as the main components of the compound organic acid disinfectant.The quantitative germicidal test was used to screen the formula of the disinfectant,and the effect of the disinfectant in the presence of organic matter was analyzed.The bactericidal ability of the drug-resistant and sensitive strains was investigated,and it was used in the precooling and segmentation packaging of broiler slaughterhouse to investigate its practical application.The results showed that lactic acid had the strongest antibacterial activity against Escherichia coli,and the bactericidal ability was significantly improved in the presence of surfactants.After contacting with Escherichia coli with different drug resistance for 30 s,the bactericidal rate of compound organic acids was 99.98%.Compared with the positive control,the bacterial reduction was more than 7.14 log CFU mL-1,and the MIC value of Escherichia coli to organic acids was determined.It was found that Escherichia coli had no resistance to organic acid disinfectant.Adding compound organic acids in the simulated precooling process of slaughterhouse,the sterilization ability was 6.5 times higher than that of sodium hypochlorite.The workers in the segmented transport link were disinfected with gloves and segmented cutters,and it was found that organic acid disinfectant could reduce the contamination rate of E.coli by 70%and 78%,respectively.In summary,this paper taked E.coli in broiler slaughterhouse as the research objective to investigate its pollution status in broiler slaughtering,and determine the key links of E.coli pollution control.This study analyzed E.coli resistance to antibiotics and commonly used disinfectants,and screend out a fast and efficient organic acid disinfectant to control the pollution of resistant E.coli,which can provide a new scheme for the prevention and control of food-borne microorganisms in broiler slaughtering. |
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