Isolation And Identification Of Escherichia Coli In Raw Meat Egg Milk In Shihezi Area And Analysis Of Some Biological Characteristics

Escherichia coli is a conditional pathogen that has long been considered part of the normal flora of the human and animal body's gut for a considerable period of time and is considered a non-pathogenic bacterium.Until the mid-20th century,diseases caused by E.coli were widely spread,and researchers realized that certain special serotypes of E.coli are pathogenic to humans and animals,especially to infants and young animals(avian).Causes severe diarrhea and sepsis.In addition,the frequent food poisoning incidents caused by food-borne E.coli O157:H7 have caused global panic,which not only seriously affects the development of the aquaculture industry,but also poses a great threat to human health.The public health significance of the bacteria has aroused people's attention.In order to investigate the contamination of E.coli in fresh meat,eggs and milk in Shihezi area and some biological characteristics of the strain,the experimental contents and results of this study are as follows:Test 1 Isolation and Identification of Escherichia coliThis trial selected different slaughterhouses,eggs and milk outlets in the Shihezi area.100parts of beef,goat liver,chicken,pork,pig liver,egg and bulk milk were collected aseptically.The samples were isolated and cultured by routine microbiological methods,and some representative strains were randomly selected for identification of biological characteristics,biochemical characteristics and hemolytic observation.The results showed that E.coli was not isolated from eggs,Escherichia coli was isolated from beef,goat liver,chicken,pork,pig liver and bulk milk,and the separation rate was 100%;five of the 60 representative strains randomly selected exhibited?hemolysis.There are 3 strains of E.coli from sheep source and 1 strain of E.coli from bovine source and milk source.Test 2 Study on some biological characteristics of Escherichia coliIn order to study the biological characteristics of food-borne Escherichia coli in Shihezi area,60 representative strains were used as research objects.The resistant pHenotype of Escherichia coli against 20 antibiotics was determined by KB agar diffusion method.Escherichia coli with serotype O157:H7 was isolated and cultured using modified sorbitol McCain(CT-SMAC)medium and the specific genes of E.coli O157 was detected by PCR.In order to explore its pathogenicity,5 strains of hemolytic Escherichia coli(No.17,No.68,No.84 in milk,No.66 in beef,No.75 in goat liver)were diluted to 1×10~9 cfu/mL and mice were infected by intraperitoneal injection.The results showed that E.coli from different sources had different resistance pHenotypes to 20 antibiotics,and the multi-drug resistance was serious.All strains were100%resistant to lincomycin,and most strains had higher resistance to tetracycline;E.coli with serotype O157:H7 was not isolated on CT-SMAC medium,and the target was not amplified by PCR.The mouse challenge test showed that the mortality rate of mice caused by milk No.68 and beef No.66 was 60%,and that of milk No.84 and goat liver No.75 was 40%,and milk No.17 did not cause mice.E.coli was successfully isolated from the liver of the dead mice.