Study On Isolation And Identification Of Salmonella From Tibet Chicken And Its Pathogenic Biological Characteristics

As a unique poultry of the Tibetan Plateau,Tibetan chickens are affected by high altitude,low air pressure and low temperature.Tibetan chickens can not only survive for a long time,but also not be affected by the environment.It can also bring fresh meat and egg products to the plateau herders.Therefore,the Tibetan chicken breeding industry has developed rapidly.The lack of attention to sanitation and disinfection management and the abuse of antibiotics have led to more and more problems during breeding.Tibetan chickens have been subject to various causes for a long time.The infestation and infection of diseased pathogens poses a serious threat to the healthy development of the plateau Tibetan chicken breeding industry.In order to explore the prevalence of Salmonella in Tibetan chickens and the biological characteristics of Salmonella in plateau areas,this experiment carried out Salmonella detection on 55 Tibetan chicken stool samples collected by rectal swabs from farms in Lhasa and Linzhi City,using bacteria The culture characteristics,morphological characteristics,and biochemical characteristics of the bacteria are preliminarily separated;then they are determined by the identification of bacterial general genes and specific genes;then serological characteristics are used to serotype the isolated strains.And use PCR technology to detect the virulence genes of the isolated strains,and then analyze the drug-resistant phenotypes and drug-resistant genotypes of the isolated strains through drug susceptibility tests and PCR tests.The following test results are obtained:A total of 8 Salmonella strains were isolated from 55 Tibetan chicken rectal swab stool samples,with a detection rate of 14.50%(8/55);Linzhi collected 25 chicken feces samples,and 5 Salmonella strains were detected.The rate was 20.00%(5/25);30 samples were collected in Lhasa,and 3 strains of Salmonella were detected,with a detection rate of10.00%(3/30),indicating that Salmonella is prevalent in chicken flocks in the two places.By serotyping the isolates.The results showed that:3 strains of Salmonella paratyphi A,accounting for 37.50%(3/8)of the isolated strains;2 strains of Salmonella typhimurium,accounting for 25.00%(2/8)of the isolated strains;Salmonella paratyphi B,Salmonella typhi and One strain of Salmonella S?o Paulo each accounted for 12.50%(1/8)of the isolated strains.It can be found that Salmonella paratyphi A is the dominant serotype among Salmonella from Tibetan chickens isolated this time.A total of 8 Salmonella strains were isolated from 55 Tibetan chicken rectal swab stool samples.The specific gene Stn was amplified,sequenced and compared with NCBI,and then MEGA7.0 was used to construct a phylogenetic tree.The Stn-L1(Nyingchi isolate No.1)sequence was found to be in the same branch as Salmonella from Egypt chicken and goat(MN537806.1,MK695165.1);Stn-L2(Nyingchi isolate No.2)sequence was in the same branch as Salmonella from Taiwan,China(CP045518.1).The results show that the isolates may have the possibility of mutual infection between humans and animals,and animals and animals.The 8 strains of Salmonella isolated from Tibetan chicken fecal swab samples in Tibet this time have detected 14 Salmonella virulence genes.The number of virulence genes tested for each strain is between 3?4,and they were isolated from the same area.The distribution of virulence genes of the strains is basically the same.The detection rate of the virulence gene sop B is 100.00%(8/8),the detection rate of sseL,orfL,rhuM,prfA,spvC and arvA are all 0.00%(0/8),sopE,orgA and ttrB appear in large Among most of the isolates,the results indicate that the Salmonella isolates in this experiment may have the ability to invade host macrophages smoothly and stably proliferate and spread.Drug susceptibility test and drug resistance gene detection found that the results of the drug susceptibility test showed that 8 Salmonella isolates were resistant to tetracycline antibiotics,such as tetracycline resistance rate reached 100.00%(8/8),to?-lactam antibiotics,For example,ampicillin,the resistance rate reaches 87.50%(7/8),and the resistance rate to chloramphenicol antibiotics,such as chloramphenicol,reaches 87.50%(7/8);at the same time,the multi-drug resistance results show that the tested Salmonella strains The proportion of resistance to 6antibiotics is as high as 37.50%(3/8),followed by the proportion of resistance to 9 antibiotics reaching 25.00%(2/8),and the proportion of resistance to 5,7,and 8 antibiotics is 12.50%(1/8),Multi-drug resistance indicates that the tested strains have developed multi-drug resistance,and each tested strain is resistant to at least 5 antibiotics;the test results of drug resistance genes show that the 8 strains of Salmonella isolates are resistant to tetracycline antibiotics(tet B),the detection rate of?-lactam antibiotic resistance gene(bla_CMY)is 100.00%(8/8),the detection rate of?-lactam antibiotic resistance gene(bla_TEM)is 87.50%(7/8),?-The detection rate of lactam antibiotic gene(bla_CTX)is 75.00%(6/8),the detection rate is 100.00%(7/8),chloramphenicol resistance(flo R),quinolones resistance(parE),aminoglycoside resistance The antibiotic(aad A2)gene detection rate was 87.50%(7/8).The results of drug susceptibility test and drug resistance gene detection test showed that there was a positive correlation between the drug resistance of 8Salmonella isolates and the positive rate of drug resistance genes This shows that the antimicrobial resistance of salmonella in the Tibetan chicken farms where sampling is located in Tibet is not optimistic,and the local epidemic prevention department should pay attention to it.This time,we isolated and identified Salmonella from Tibetan chickens in some areas of Tibet and conducted a certain study on the biological characteristics of the isolates.After that,the carrying and distribution of virulence genes and drug resistance genes of the isolated strains were further studied.It provides a certain theoretical basis for the prevention and control of Salmonella from Tibetan chickens in Tibet in the future,and provides certain data support for the subsequent rational use of antibiotics.