| The diarrhea caused by pathogenic E.coli is a common disease in the fleshy sheep breeding industry.The impact on fleshy sheep farming should not be underestimated.Because of the complex and diverse virulence factors and O serotypes,it has long been caused by the abuse of antibiotics.The multi-drug resistance of pathogenic bacteria is serious,and there are large differences in different regions.At present,there are no ideal immune vaccines and other factors,which brings severe challenges to the prevention and control of E.coli disease in productionIn order to reveal the carrying status and virulence gene distribution of pathogenic E.coli in clinically healthy fleshy sheep,a total of 925 samples of clinical healthy fleshy sheep source anal swab samples from parts of Jiangsu Province were collected from 2017 to 2018,and the main methods were used by PCR.Virulence genes(K88,K99,987P,F41,HPI,LEE,ST1,ST2,LT1,Stx1,Stx2,Stx2e)were rapidly detected and isolated.The results showed that there were differences in virulence factors in different regions,and it is different from the previously reported distribution of virulence genes of pig,cow,rabbit and avian E.coli.The positive rate of Stx1+toxin(31.57%)is too high,but it is not pathogenic in fleshy sheep.It is likely that the sheep is the storage host of human pathogenic E.coli.987P,F18,ST2,Stx2e were not detected in the samples collected;the total detection rate of K88+ was 1.62%,which was only detected in Yangzhou and Haimen areas;F41+ The total detection rate of K99+was 0.97%and 0.11%,respectively,which was detected in Yangzhou City;the total detection rate of HPI+ was 40.43%;the total detection rate of LEE+was 4.65%;the total detection rate of HPI+ was 31.57%;Stx1+The detection rate was 31.57%;Stx2+was detected only in Yangzhou,Haimen and Guanyun,and the total detection rate was 2.83%;ST1+ was only detected in Yangzhou,and the total detection rate was 0.11%.A total of 591 pathogenic E.coli were isolated,and the isolates were divided into 13 different virulence factors,followed by K88+(11 strains),F41+(1 strain),LEE+(32 strains),and HPI+(211 strains),Stx1+(176 strains),Stx2+(7 strains),K88+HPI+(4 strains),LEE+HPI+(38 strains),LEE+Stx1+(6 strains),HPI+Stx1+(83 strains),HPI+Stx2+(6 strains)Strain,LEE+HPI+Stx1+(11 strains),LEE+HPI+Stx2+(5 strains).In order to find out the O antigenic type of pathogenic E.coli isolates from clinical health,the 235 strains were tested for O antigen type by glass plate agglutination test.The results showed that there were 120 strains(51.06%)stereotyped,073 As the dominant serotype,3 strains(1.28%)were 08 serotypes,3 strains(1.28%)were 020 serotypes,97 strains(41.28%)were 073 serotypes,and 8 strains(3.40%)were 078 serotypes.Nine strains(3.83%)were 0157 serotypes,which differed greatly from the previously reported porcine,chicken,rabbit,and bovine pathogenic E.coli O antigen types.In order to understand the differences in pathogenic E.coli virulence genes in different feeding patterns,seasons,and varieties,the results of comparative analysis showed that the virulence factor detection rate was generally stocked>half in different feeding modes.Closed>fully closed;the detection rate of virulence factors in different seasons is generally summer>autumn>winter>spring;the detection rate of virulence factors of different virulence factors is generally Boer goat hybrid>Lake sheep>Goat>Tibetan sheep.In order to find out the carrying status and virulence gene distribution of pathogenic E.coli in clinical diarrhea,we collected 75 samples from 24 fleshy sheep farms in Jiangsu Province from 2017 to 2018.Virulence genes(K88,K99,987P,F41,HPI,LEE,ST1,ST2,LT1,Stx1,Stx2,Stx2e)were rapidly detected and isolated.Statistics show that the virulence factors in different regions are different,and it is different from the previously reported distribution of virulence genes of pig,cow,rabbit and avian E.coli.K99+,987P+,F41+,F18+,ST1+,ST2+,Stx2e+are not detected in the collected samples;the total detection rate of K88+is 6.67%,only in Yangzhou and The detection rate in Haimen area was the highest;the highest positive rate of HPI+was 46.67%,and the total detection rate of LEE+was 24%.The positive rate of Stxl+detection was 33.33%.Stx2+was detected only in Yangzhou,Haimen and Fuyang,and the total detection rate was 4%.A total of 56 pathogenic E.coli were isolated,and the isolates were divided into 11 different combinations of virulence factors,followed by K88(5 strains),HPI+(4 strains),LEE+(2 strains),Stx1+(9 strains).Stx2+(1 strain),HPI+Stxl+(12 strains),HPI+Stx2+(2 strains),LEE+HPI+(3 strains),LEE+Stx1+(12 strains),LEE+Stx2+(1 strain),LEE+HPI+Stx1+(5 strains).To determine the O antigenic type of the pathogenic Escherichia coli isolate from clinical diarrhea,the O antigen type was determined by the 56 strains of the glass plate agglutination test.The results showed that 33 strains(58.93%)were identified and 073 was Among the dominant serotypes,one strain(1.79%)was 08 serotype,24 strains(42.86%)were 073 antigenic type,3 strains(5.36%)were 078 antigenic type,and 5 strains(8.93%)were 0157 antigenic type,and There have been large differences in the antigenic forms of pathogenic Escherichia coli between pigs,chickens,rabbits and cattle.In order to study the drug susceptibility of pathogenic E.coli,and provide scientific guidance for clinical drug use,13 antibiotics were used to treat 291 strains of pathogenic E.coli isolated from health and diarrhea in Jiangsu Province using drug sensitive paper agar diffusion method.Analysis of drug susceptibility characteristics.The results showed that the overall clinical health and diarrhea mutton isolates had little difference in sensitivity to 13 drugs,but there were differences between different regions and different farms.Most strains were on polymyxin B and fosfomycin.More sensitive,doxycycline resistance is the strongest,followed by tetracycline and neomycin.In order to determine the virulence of pathogenic E.coli with different virulence factors,three clinical isolates of healthy meat sheep with O antigen type 073(HPI+,Stx1+,HPI+Stx1+strain each)were selected,and half of the mice were used.The lethal dose(LD50)method measures its virulence.The results showed that the isolates with both HPI+and Stx1+had the strongest virulence,followed by the isolates with Stx1+alone.The isolates with HPI+alone were relatively weak,showing the number and virulence of virulence factors.Positive correlation. |
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