Isolation And Identification Of Pathogenic Bacteria Of Lamb Diarrhea And Analysis Of Intestinal Flora Of Sick Sheep

Lamb diarrheal disease is one of the problems plaguing the development of sheep industry,and its pathogenesis is mainly caused by E.coli infection of sheep,which is mainly characterized by diarrhea in sheep,damage and bleeding of various parenchymal organs.Moreover,in the increasingly complex breeding environment,E.coli is prone to co-infection with other pathogenic bacteria,which increases the mortality rate of sick sheep.Sheep-derived E.coli disease is currently a relatively harmful disease in veterinary clinics,which is highly infectious and harmful,and also brings certain threats to human public health security.At present,the research on poultry-derived and pig-derived E.coli has been relatively in-depth,which provides guidance for the prevention and treatment of E.coli disease.However,in recent years,the domestic sheep and mountain breeding industry has developed rapidly,and the breeding volume has occupied the first place in the world,and sheep-derived E.coli infection will affect the survival rate of lambs,and in adult sheep E.coli often causes mixed infection with other germs,accompanied by strong pathogenicity,damaging the economic benefits of the sheep industry.In addition,long-term clinical overdose or irrational use of antibiotics has led to the emergence of a large number of drug-resistant strains,which has brought a certain degree of difficulty to the prevention and treatment of this disease.In this study,the pathogenicity and drug resistance of two strains of E.coli from sick sheep in Laiwu area of Shandong Province were isolated and identified,as well as high-throughput sequencing analysis,aiming to provide reasonable and positive treatment options for sheep farms and reduce the losses caused by E.coli disease to the sheep industry1.Isolation and identification of sheep-derived E.coli diseaseThe laboratory isolated two strains of sheep-derived E.coli from the liver and lungs of three sick and dead sheep from the diarrheal disease materials of black goats in Laiwu area,Shandong Province,through bacterial isolation and identification and pathogenic testing.Preliminary analysis using Bruker’s automated bacterial mass spectrometer ruled out other pathogenic infections such as Salmonella,confirming that the diarrhea of the black goat was caused by E.coli infection and caused pathological damage of the intestine,liver and lungs with bleeding symptoms.The affected sheep are emaciated,their orbits are sunken with bloodshots,the mucous membranes are white,and the hind limbs,stomach and anus are contaminated with feces.After comprehensive serotype identification and biochemical experiments,it was found that the strains isolated from the liver and intestine were extraenteral pathogenic Escherichia coli(Ex PEC)and intestinal toxin-producing Escherichia coli(ETEC),named E.coil 1 and E.coil 2,The virulence factors and MLST steward gene carrying of the two E.coli strains were detected by PCR test.The results showed that E.coil2 carried more virulence factors and was more pathogenic,and the typing of E.coil 1 and E.coil 2MLST were ST648 and ST32,respectively.The results of drug sensitivity test showed that E.coil 1 was highly sensitive to norfloxacin and ampicillin,and E.coil 2 was highly sensitive to doxycycline and penicillin.The two strains of Escherichia coli had differences in bacterial homology,virulence factors and drug resistance genes.2.Metagenomic analysis of sheep-derived Escherichia coli and analysis of 16 s r RNA microorganismsThe small intestine,cecum and liver of the sick and dead sheep were sent to Qingdao Qingke Co,Ltd.for high-throughput sequencing analysis,mainly including metagenomic sequencing analysis and 16 s r RNA microbial sequencing analysis,and the sequencing results showed that abnormal elevation of E.coli content was detected in the intestinal microbial community of the diseased sheep.In particular,the E.coil 2 group changed drastically,and the number of various flora changed significantly,which was related to the determination of intestinal toxin-producing Escherichia coli(ETEC)in the intestines of diseased sheep.E.coil1 group had small changes in the gut microbiota and no significant differences.However,the presence of extraenteral pathogenic Escherichia coli(Ex PEC)was detected in liver samples,and the cause of E.coli entering the chest cavity of animals due to physical damage was ruled out by dissecting the carcass of the diseased sheep and observing the integrity of its diaphragm.Based on the results of this test,various characteristics and types of E.coli were determined,which provided assistance for the prevention and treatment of E.coli in sheep.