Isolation,Identification,Drug Resistance And Genotyping Of Salmonella Gallinarum From Anhui Province

Avian salmonellosis is a general term for acute or chronic diseases of poultry caused by multiple members of the genus salmonella.The disease can be transmitted not only horizontally through direct contact,but also vertically by growing eggs,which has caused huge economic losses to the poultry industry.For a long time,due to the unreasonable use of antibiotics in poultry industry,the drug resistance of salmonella from poultry has been enhanced,which has brought difficulties to the treatment of salmonellosis.As one of the main hosts of salmonella,chicken plays an important role in the spread of salmonella and food contamination.However,there are few comprehensive research reports on the dominant serotype,drug resistance and genotyping of salmonella gallinarum in Anhui Province.In this paper,Salmonella gallinarum was isolated and identified in Anhui Province,and its epidemic serotype was determined.The drug resistance and genotype of salmonella gallinarum in Anhui Province were studied by microbiological and molecular biological methods.The main research work and results completed are summarized as follows:1)Isolation,identification and serotype detection of salmonella from chicken.In this paper,PBW-MM-XLD4 grading culture was used to selectively isolate and culture salmonella from clinical samples.70 strains of salmonella from chicken were obtained by phenotypic identification of suspected strains and analysis of bacterial 16S rRNA gene.Detection of serotypes of 70 strains of Salmonella from chickens,the results showed that all the isolated strains were distributed in 5 serotypes,including 38 strains of mouse typhoid type,27 strains of enteritis type and 3 strains of Cottbus type.Thompson type 1 strain,infant type 1 strain.The results showed that mouse typhoid type and enteritis type were the dominant serotypes of salmonella gallinarum in Anhui Province.2)Study on drug resistance of salmonella from chicken.The sensitivity of 70 strains of salmonella from chickens to 14 common antibiotics was detected by K-B disk method.the results showed that the tested strains were highly sensitive to imipenem,amikacin,ciprofloxacin and enrofloxacin,and the sensitivity of the tested strains to imipenem,amikacin,ciprofloxacin and enrofloxacin was high.However,?-lactam,tetracycline chloramphenicol and sulfonamides showed different degrees of resistance to ?-lactam,tetracycline chloramphenicol and sulfonamides.Among the tested strains,23 strains were resistant to three or more antibiotics,the multidrug resistance rate was 32.9%,and the most common multidrug resistance spectrum was AMX-CRO-TET-CHL-TMP.At the same time,70 strains of Salmonella from chickens were detected for carrying seven drug resistance genes.The results showed that the detection rates of p-lactam resistance gene blaTEM,tetracycline resistance gene tetA and tetB gene and sulfonamide sul2 gene were 48.6%,48.6%,15.7%and 28.6%,respectively.The results showed that salmonella gallinarum from Anhui Province had strong drug resistance.3)Detection of virulence genes of salmonella gallinarum.The virulence genes(invA,sseL,mgtC,siiE,sopB),virulence plasmid gene spvB and enterotoxin gene stn on virulence island SPI-1-5 carried by 70 strains of salmonella gallinarum were detected by PCR.The results showed that the detection rates of invA,mgtC and stn genes were 100%,and those of seeL,siiE,sopB and spvB genes were 64.3%,98.6%,97.1%and 68.6%,respectively.The results showed that the virulence gene carrying rate of salmonella gallinarum isolates was high.4)Genotyping of salmonella gallinarum.70 strains of salmonella were genotyped by ERIC-PCR and CRISPR,respectively.The results showed that ERIC-PCR could not distinguish salmonella from chickens with the same serotype,while CRISPR could distinguish salmonella from the same serotype.Among them,27 strains of salmonella enteritidis were divided into 3 genotypes,36 strains of salmonella typhimurium were divided into 9 genotypes.The results showed that CRISPR had a good genotyping effect in salmonella genotyping.In summary,70 strains of salmonella gallinarum were isolated and identified from diseased chicken samples in Anhui area.Mouse typhoid type and enteritis type were the dominant serotypes,and mouse typhoid type and enteritis type salmonella were divided into 3 and 9 genotypes,respectively.Salmonella from chicken isolated from Anhui Province has serious drug resistance and carries a variety of virulence genes.These results can provide guidance for the rational use of antibiotics in clinic,and also lay a foundation for the epidemiological study of salmonella gallinarum.