| The embryonic period and the chicks that have just emerged from the shell are in the most vulnerable period of their life.The development of this stage is still imperfect,the resistance is poor,and it is easy to be affected by various external factors,resulting in diseases,resulting in low hatching rate and low rate of health.It has a great impact on the economic benefits of hatcheries and breeder farms.Therefore,investigating the types of major pathogens that currently cause embryonic disease in chicks is of great significance for chick embryo disease and for improving the survival rate of chicks.1.In order to investigate the main pathogens of diseased and weakly infected chicks,90 newly-occupied diseased and weak chicks were collected.Anatomically observe the pathological changes,isolate the bacteria from the liver,observe the bacterial colony morphology,extract the DNA of the isolated strain,amplify and sequence the 16SrDNA gene sequence,and compare the sequencing results with the standard strain sequence of the GenBank database.In result,the sick and weak chick's abdominal circumference was larger.Through the anatomy,their abdominal subcutaneous jelly,yolk malabsorption and khaki liver were observed.Under the microscope,we observed that the liver was congested and fatty degeneration.A total of56 isolates were isolated,with a separation rate of 62.2%(56/90).The Enterococcus faecalis separation rate was 46.4%(26/56),Escherichia coli separation rate was 16.1%(9/56),Staphylococcus aureus separation rate was 14.3%(8/56),Bacillus separation rate was 8.9%(5/56),Acinetobacter baumannii separation rate was 5.3%(3/56),Candida marshes separation rate was 3.6%(2/56),Citrobacter separation rate was 1.8%(1/56),Achromobacter separation rate was 1.8%(1/56),and Bacillus licheniformis separation rate was 1.8%(1/56).The results suggest that newly hatched chicks infected with 9 species of bacteria and the main pathogens are Enterococcus,Escherichia coli and Staphylococcus aureus.This laid the foundation for the prevention and treatment of chick bacterial infection.2.In order to explore the virulence and drug resistance of Enterococcus faecalis,this experiment determined the half-lethal dose of Enterococcus faecalis to chicken embryos,and the most sensitive drug test of 15 kinds of antibiotics and 15 drugs.The results showed that the survival time and mortality of chicken embryos were significantly dose-dependent after inoculation of 10 times serial concentration of E.faecalis and chorioallantoic membrane.The median lethal dose of Enterococcus faecalis chicken embryos was 3.03×10~3 cfu/mL.The drug sensitivity test found that Enterococcus faecalis has strong resistance to cephalosporins and is sensitive to penicillin and vancomycin.In this experiment,the virulence model of the faecal faecal chicken embryo was successfully established,and the effective drug of Enterococcus faecalis was screened.3.In order to establish a rapid,specific and sensitive method of detecting source of chicken dung enterococcus,to facilitate the production and application in disease prevention and control,this study refer to Gen Bank published chicken excrement enterococcus in whole genome,using Primer Express5.0 software design of a pair of specific primers,the sensitivity,specificity,repeatability test,and techniques through the evaluation of the clinical practicability.Results show that the method standard curve linear relationship is good,the correlation coefficient R~2=0.955;The method is of high sensitivity and minimum detectable dung enterococcus can reach 10~1cfu/mL;Specificity is strong,no cross reaction with other chicken source pathogenic bacteria;Repeatability tests the variation coefficient is less than 2%,relatively stable.The DNA extracted from the liver tissue of the young chicken was used as a template,and the specific amplification curve appeared after the established SYBR Green I LC-PCR method.This method can be used in clinical dungs enterococcus detection. |
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