Distribution And Characteristics Of Yersinia Enterocolitica In China And Investigation Of Anaplasma Phagocytophilum In Marmota

Part Ⅰ Distribution and characteristics of Yersinia enterocolitica in ChinaObjective Based on the analysis of the etiology and PFGE types of Yersinia enterocolitica in different regions of China from 1980 to 2019,this study provides a basis for the prevention and control of Yersinia enterocolitica.Methods 6847 strains of Yersinia enterocolitica isolated from different samples from different regions in China were analyzed by pulsed field gel electrophoresis(PFGE).The serotypes,biochemical phenotypes and virulence gene distribution were studied.Results1.6847 strains of Yersinia Enterocolitica were mainly from animals(88.36%,6050/6847),next were diarrhea patients(6.44%,441/6847),food(4.76%,326/6847)and environment(0.44%,30/6847).Among the strains of animal origin,pigs accounted for the highest proportion(43.24%,2616/6050),followed by rodents(27.69%,1675/6050).2.There were 2047 pathogenic strains and 4800 non-pathogenic strains in Yersinia Enterocolitica and only two serotypes in pathogenic strains,O:3 accounted for 88.96%(1821/2047);O:9 for 11.04%(226/2047).The pathogenic strains in 18 provinces and autonomous regions were mainly of O:3 serotype and Ningxia Hui Autonomous Region of O:9 serotype.There are many serotypes of non-pathogenic bacteria,which generally have more positive biochemical reactions than pathogenic strains.3.There were two combinations of pathogenic strains,among which type Ⅰ accounted for92.67%(1897/2047)and carried ail,ystA,yadA and virF genes,type Ⅱ accounted for 7.33%(150/2047)and was the pathogen that lost the virulence plasmid.Among the non-pathogenic strains,62.83%(3016/4800)were type Ⅲ,36.19%(1737/4800)were type Ⅳ.The above four typical genotypes(Ⅰ,Ⅱ,Ⅲ,Ⅳ)were distributed in all the 22 provinces surveyed.In addition,non-pathogenic strains only carried ail(Ⅵ)or both ail and ystB(Ⅴ)genes were found in some provinces.4.1821 strains O:3 were divided into 93 PFGE types and distributed in 19 provinces and autonomous regions.Among them,K6GN11C30021 and K6GN11C30012 were the dominant bands(46.35% and 22.5%,respectively),and 75.38% of the human strains were the same as those isolated from local animals and food 226 strains O:9 were divided into 14 PFGE types,which were distributed in 8 provinces and autonomous regions.77.78% of the human strains were consistent with those isolated from local animals and food.Conclusion1.Yersinia Enterocolitica is widely distributed and has many hosts in China.There are only two serotypes of pathogenic strains and many serotypes of non-pathogenic strains.2.Non-pathogenic bacteria generally have more positive biochemical reactions than pathogenic bacteria,indicating that they may have stronger biochemical metabolism and environmental adaptability.The main biochemical codes of O:3 serotype and O:9 serotype did not cross in the pathogenic strain,indicating that the two serotypes might have different biodegradability and Niche.3.The predominant PFGE bands of pathogenic bacteria are relatively concentrated and widely distributed in different regions.Most human strains are consistent with those isolated from local animals and food,people should be alert to the risk of infection from multiple sources such as livestock,poultry,food and the external environment.Part Ⅱ investigation of Anaplasma phagocytophilum in MarmotaObjective To investigate the condition of Marmot carrying Anaplasmosis phagocytophilum in the natural foci of plague,and to provide scientific basis for the prevention and control of Anaplasmosis and plague.Methods1.The nest-like sequences of 16 S rRNA gene and groESL gene were used to sequence2.BALB/C mice and L929 cells were infected with the Phagocytic anamorphosis tissue grinding fluid,the 16 s rrna gene and the groESL gene of Phagocytic anamorphosis were detected and sequenced.Results1.A total of 212 marmots were collected during plague surveillance from 2019 to 2020 in plague endemic areas of the qinghai-tibet plateau,with a total positive rate of 20.75%(44/212).The positive rate of anaplasma phagocytophilum in captured marmots was 19.21%(29/151),the detection rate of dead Marmot was 24.59%(15/61).2.The nucleotide identity of the 16 S rRNA gene,the Groe EL gene and the groESL amino acid sequences of the Phagocytic anamorphosis from Marmot were 99.52%(1463/1470)with the reference strain HZ(CP0000235.1),respectively,94.07%(1173/1247 and 99.52%(413/415).3.Phagocytic anamorphosis was successfully infected in Balb/c mice and L929 cellsPhagocytic anamorphosis could be detected again in mice and L929 cells.Conclusion1.In this study,Marmota Marmota was first found to carry anaplasma phagocytophilum with a high carrier rate,which was distributed in many organs of the body.2.Marmots may be storage hosts for anaplasma phagocytophilum.