Plasmid DNA Analysis And Resistant Gene Location Of Multiple Drug-Resistant Salmonella From Chicken

Salmonellosis is one of the common infection diseases caused by the Salmonella bacteria. It can be divided into Pullorum, Typhusavium and Paratyphusavium. The performance of Chick is depression, loss of appetite, diarrhea and high mortality rate, which have done great harm to the poultry industry. In the last two decades, the incidence of resistance to antimicrobial agents among Salmonella has been steadily rising in food as well as in clinical isolates. This increase seems to be associated with the high use of antibiotics in livestock and in human health care. Particularly the emergence and dissemination of MDR (Multiple drug resistance) Salmonella have become a major concern for global research scholar. This study aimed to evaluate the antimicrobial susceptibility profiles, prevalence of MDR, serotype, plasmids presence and resistant gene location of pathogenic Salmonella isolated from chickens in Shuang Cheng Sui Hua and Xiang Fang. On this basis, to analyze the relationship between the resistance spectrum, serotypes, and plasmid profiles, and their resistance gene positioning. This Provide a reference for rational drug treatment of chicken salmonellosis and a theoretical basis for the study of resistance reversal agentsThirteen pathogenic Salmonella strains were isoiated from primary diagnosis of salmonella disease onset of illness in the chicks hatching and rectum debris with conventional method. The isolates were identified by biochemical; Serogroups were determined by Salmonella diagnostic serum using the slide agglutination method. Putative isolates were definitively identified as Salmonella spp. By PCR with the primers, which amplify a252-bp Salmonella-specific produet from the invA gene. The results indicted that the thirteen studied Salmonella isolates belonged3serogroup:A(n=1,7), B(n=2,3、9)and D(n=10,1、2、4、5、6、8、10、11、12、13). The superiority group is D(77%). All of the isolates were positive when amplifying the InvA gene.Thirteen isolates were tested for their sensitivity to10antimicrobial agents by Kirby-Bauer method. The susceptibility and resistance of the Salmonella strains were defined according to the criteria suggested by the NCCLS; Plasmids were purified from isolates by alkaline-lysis method and electrophoresed in0.7%(w/v) agarose. The plasmid DNA was cleaved with restricted inscribe enzyme HindⅢ.Then analyzed endonuclease products. The relationship between the serotype and plasmid profile, the antibiotic resistance profile and plasmid profile weir analyzed. All strains showed resistance to more than two kinds of antibacterials, some even reached eight. Of the13strains,100%was resistant to Tetracycline,92.3%to Compound Sulfonamides,84.6%to Ofloxacin, 84.6%to Norfloxacin,84.6%to Ciprofloxacin,69.2%to Ampicillin,23.1%to Cephazolin and7.7%to Chloramphenicol. However, they were still sensitive to Gentamicin and Kanamycin. Plasmids were discovered in13strains of Salmonella isolates(100%). There are no obvious relationships between resistance pattern and plasmid profile. The strains from the same place have similar plasmid profile, and the strains from the different place have different plasmid profile. The plasmid profile of the strains which have the same serotype can be the same or not. The plasmid profile of the strains which have different serotype can also be the same or not which indicates that there is no relationship between serotype and plasmid profile. Strains isolated in the same period have the same plasmid profile, while they can resistance profile, which indicates that the stability of plasmid profile is higher than resistance profile.The plasmids which presenced in the isolates were eliminated by high temperature and SDS. The plasmid-mediated resistance were located by the pair sensitivity tests before and after the plasmids eliminated. Our studies revealed that plasmids of13isolates were completely (100%) eliminated. The Pair sensitivity tests before and after the plasmids eliminated suggested that the genetie determinants conferring resistance to TET were present in the plasmids of1、2(10%), to CIP, OFL and TET were present in the plasmids of3、4、7(30%), to CIP, OFL, NOR and TET were present in the plasmids of5、8、9(40%), to CIP, OFL, SXT and TET were present in the plasmids of6、12(40%), to AMP, CIP, OFL, NOR and TET were present in the plasmids of S9(50%), to CIP, OFL, NOR, SXT and TET were present in the plasmids of13(50%).