| Salmonella is the major food-borne pathogen causing human intestinal diseases.In hope of expanding the application,a rapid detection method of E.coli and Salmonella by test strip,which is patented for utility model,is adopted in the early stage.In this experiment,380 samples of animal-derived food industry chain in Korla are evaluated for rapid strip detection of Salmonella and 1385 samples are isolated and identified for further detection of the virulence genes and drug resistance of Salmonella,which provide a scientific basis for detection and control of food-borne Salmonella.Research contents in this paper are as followed:(1)the sensitivity of Salmonella microfluidic paper-based analytical devices(SE-?PADs)in sample processing could be efectively improved by optimizing the Salmonella bacteriostatic solution of the enrichment broth,and the false positive could be reduced.The optimum pH,time and temperature of SE-?PADs using BPW are 7.0,5 h and 37? respectively.The initial screening rate of SE-?PADs is 6.6%(25/380)and 10 Salmonella isolates are detected.The positive coincidence rate(sensitivity)of SE-?PADs with national standard method is 100%and negative coincidence rate(specificity)94.92%.(2)1385 samples from 3 markets,2 slaughterhouses and 3 sheep farms in Korla are isolated and identified.The total detection rate of 3.75%(52/1385),among which the detection rate of chicken source is 5.34%,the detection rate of cattle source is 3.85%,the detection rate of pig source is 3.73%,and the detection rate of sheep source is 2.79%.The highest contamination rate of Salmonella in the market is 5.13%while the highest detection rate of operational tools is 13.00%,followed by sample swabs 7.79%.(3)The virulence genes(invA?spvB?spvR?sopB?ssaQ?spvD)of Salmonella are isolated and identified,with the highest detection rate of sopB being 61%(32/52),followed by invA being 38%(20/52),and ssaQ being 32%(1 7/52).The carrying rate of invA gene is 56%(9/16)in cattle sourced Salmonella and 41%(7/17)in sheep sourced Salmonella,and the highest carriers of toxicity genes are spvR,invA and ssaQ genes in three industrial chains of farms,slaughterhouses and markets.Six virulence genes coexist in Salmonella.The isolated and identified Salmonella from cattle source,chicken source all produced high resistance to medicamycin,ampicillin,piperacillin,while sheep sourced Salmonella produced high resistance rates to medimycin,piperacillin and cefotaxime.Salmonella multi-drug resistance is mainly diresistance,three-resistance and four-resistance and the drug resistance rates are 10%,15%and21%respectively.It is found that two Salmonella strains even could tolerate 15 kinds of antibiotics.Based on the above results,it is concluded that SE-?PADs rapid detection method could be applied to animal-derived food samples in different links and food-borne Salmonella contamination mainly exists in the operating tools of market links.Meanwhile,virulence genes have been widely distributed in different animal origins,and drug resistance is serious and multidrug resistance is widespread.Therefore,highly priority should be paid by local animal health supervision departments to strengthen the disinfection and control of Salmonella in market links. |
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