Identification Of Salmonella In Dead Embryos And Study On Their Drug Resistance Characteristics Of Some Farms In Shandong Province

Salmonella is a general disease caused by salmonella bacteria,which is currently a major threat to the global poultry industry.Salmonella belongs to Gram-negative bacteria,poultry infected salmonella is mainly divided into Salmonella Enteritidis,Salmonella Pullorum and Salmonella typhimurium.Salmonella infection is not only associated with the morbidity and mortality of farms,but can even cause gastroenteritis in humans,resulting in150,000 deaths each year.Salmonella Pullorum mainly infected with 3 weeks of age chicks,the main clinical symptoms are white feces,serious can cause dehydration,or even large-scale death,adult chickens infected,although mostly recessive disease,but will lead to a significant decline in the fertilization rate of chickens,egg yield and incubation rate significantly,thus causing serious economic losses to the farm.In order to understand the prevalence of salmonella in nine chicken swarms in Shandong Province in the same period in 2019,the horizontal transmission of drug-resistant genes and drug-resistant phenotyms was studied.This study selected the 18-day-old dead embryo?90per chicken farm?of nine chicken flocks in the same period of time to assess the prevalence and hazard warning of salmonella in the chicken population of Shandong Province in 2019.Aseptic collection of 810 unshell dead embryoliver liver,spleen and egg yellow,mixed grinding,pre-bacterial,bacteria-enhanced and selective culture of the identification of the medium,suspected colonies after PCR method and microbiota quality spectrometry identification and other methods to complete the identification of salmonella isolates.At the same time,the study analyzed the serotype,MLST parting,toxicity gene,drug-resistant gene and the horizontal transmission of drug-resistant phenotype in all salmonella isolates.The results showed that five salmonella-positive farms were detected in nine chicken plants.Of the 810 dead embryos,a total of 177 salmonella were isolated,and the positive rate of this separation was 21.85%?177/810?.Among the five salmonella-positive chickens,Bari-chickens,green-shelled egg chickens and reed chickens detected Salmonella Enteritidis,Salmonella Pullorum.Chicks,green-footed hemp chicken,etc.detected the bacteria white sandsalmon bacteria.The main prevalence of salmonella in the five positive chicken farms is chicken white dysentery.A total of 4 ST types were detected using bacterial multi-point sequence typing?Multilocus sequence typing,MLST?,and a total of 4 ST types were detected:ST11,ST92,ST470,ST2151.ST92 is the main popular ST type.There is a clear regularity in MLST parting,and the genetic direction flows to ST11-ST470-ST92-ST2151.Among them,ST11 as the core sequence type.The study found that salmonella multiple resistance rate was highest in 100-day chickens,reaching 93.48 percent,and that salmonella strains isolated from 100-day chickens were co-infected with the same host.In response to this,the study carried out follow-up drug-resistant genes,toxic genes,plasmid binding and kinship analysis of the 100-day chicken source salmonella isolates.Thirty-four of the 90 unshelled dead embryos in the 100-day flock detected salmonella,and 12 of the dead embryos detected co-infection of chicken white dysentery and enteritis salmonella.Of the 46 strains of salmonella isolated,25?54.35%?of chicken white sandmen bacteria and 21 strains of salmonella?45.65%?of enteritis.The results of 46 salmonella resistance to 14 antimicrobial drugs showed that the resistance rate of isolated bacteria to erythromycin was as high as 100%?46/46?,followed by ampicillin,with a resistance rate of89.13%?41/46?,for tetracycline,streptomycin,The resistance rate of cephalosporine was56.52%?26/46?,67.39%?31/46?and 82.61%?38/46?,respectively,and was sensitive to polymycomycin,compound neonomine,and meifsin.93.5%?43/46?of strains are resistant to at least three or more drugs.The drug resistance characteristics of 12 strains of enteritis salmonella and chicken white salmonella of the same host source of the co-infection were analyzed and the drug-resistant pinformation heat map was plotted.It was found that the chicken white samen strains isolated in the same dead embryo had a broader drug resistance spectrum than the salmonella strain of enteritis.Quinolones and sulfonamide resistant genes were detected through PCR,with a maximum detection rate of 100%?46/46?,followed by bla_PSESE 97.83%?45/46?,bla_CTX-M95.65%?44/46?and sul2 97.83%?45/46?were not detected on the plasmid splastles.The success rate of the plasmid joining experiment was 89.13%?41/46?,73.17%?30/41?the drug resistance spectrum narrowed,and the combined subs detected bla_TEM?100%?,bla_CTX-M80.49%?33/41?,sul1 58.54%?24/41?and sul3 73.17%?30/41?.The MLST typeing results showed that 46 salmonella strains were divided into three ST types:ST11?21/46,45.65%?,ST92?20/46,43.48%?and ST2151?5/46,10.87%?.Cluster analysis can be seen that ST11 and ST92,ST470,ST2151 each differ in an allele.By constructing the smallest spanning tree,this study found that the isolated plants ST11,ST1558,and ST1747 formed a clone group,and ST92 and ST2151 formed another clone group.These five STs share a common genetic background and are close to each other.The results of this study show that some chicken farms in Shandong Province have a serious prevalence of salmonella,the main prevalence of serotype is chicken white sandmenia,the main epidemic of ST type ST92.100-day chicken sage salmonella is mainly caused by infection of chicken white dysentery and enteritis salmonella,and found that the same host has two serotonin salmonella infection,MLST type indicates that its kinship is closer,salmonella isolated strains have multiple resistance and carry multi-drug resistance genes,The plasmids have been passed horizontally in the environment.The assessment of the prevalence of salmonella,the characteristics of drug resistance and the risk of co-infection in this study are of great reference to the formulation and implementation of salmonella purification measures in chicken farms.