| Salmonella and Proteus mirabilis are the most common bacteria in the intestines of humans and animals,causing diarrhea in both humans and animals.The increasing tendency of these two bacteria to acquire antimicrobial resistance is of concern since only a limited number of antimicrobials remain available for veterinary clinical use to cure sika deer disease.Plasmids are capable of autonomous replicate and express the genes they carry,and are one of the important movable elements for horizontal transfer of resistance genes,and integrons are usually located on plasmids,which promote bacterial resistance to antibiotics by capturing different resistance gene boxes and transferring with the plasmid.In this study,300 swab samples of diarrheic fawns in Shuangyang District,Changchun City were collected to isolate and identify Salmonella and Proteus mirabilis,detect drug resistance and drug resistance genes of isolated bacteria,explore the relationship between integrators and drug resistance carried by isolated bacteria,and explore the mechanism of drug resistance genes of Salmonella and Proteus mirabilis through ligation test.It can provide reference data for disease prevention and antibiotic use in sika deer in Shuangyang District,and provide reference for future diseases caused by Salmonella and Proteus mirabilis.In this study,300 samples of diarrheic fawns were collected from 10 villages in Shuangyang District（Dayingzi Village,Wangxi Village,Wangdong Village,Caijia Village,Fangjia Village,Shixi Village,Hongtu Village,Cuijia Village,Dali Village and Chen Village）.A total of 23 strains of Salmonella and 15 strains of Proteus mirabilis were isolated,and 19antibiotics such asβ-lactams and quinolones were selected for susceptibility testing to explore the multi-drug resistance of these two isolates.Salmonella and Proteus mirabilis had the highest resistance rate to ampicillin and azithromycin（100%resistance）,and Proteus mirabilis had the same 100%resistance rate to tetracycline and doxycycline;Salmonella and Proteus mirabilis had the lowest resistance to nitrofurantoin,4.4%（2/23）,20.0%（3/15）,respectively.The multidrug resistance of Salmonella reached 95.7%（22/23）,and the common resistance number was 17 resistance,of which two strains were 19 resistant;Proteus mirabilis are all multidrug-resistant bacteria,with a common resistance of 15,one strain resistant to 18antibiotics,and only moderately sensitive to nitrofurantoin.In order to explore the relationship between drug resistance genes carried by isolates and drug resistance,21 drug resistance genes such asβ-lactam and quinolones were detected.The results showed that the detection rate of Salmonella drug-resistant genes was 100%（23/23）,such as sul I,ant（3’’）-Ia,aad A2,aph（3）-IIa,qnr S,Flor and tet A.The detection rate of Proteus mirabilisis sul I,ant（3’’）-Ia resistance genes was 100%（15/15）;For the first time,one strain of Salmonella and one strain of Proteus mirabilis carried the NDM-1 gene were isolated in the feces of diarrheic fawns.The results showed that the resistance genes carried by Salmonella and Proteus mirabilis were consistent with the drug resistance phenotype,and drug susceptibility testing and drug resistance gene detection showed that the drug resistance of Salmonella deer source and Proteus mirabilis in Shuangyang District was relatively serious.On the basis of 23 strains of Salmonella and 15 strains of Proteus mirabilis,the detection results showed that the detection rate of Salmonella class I integraton was 87%（20/23）,and the detection rate of class I integraton of Proteus mirabilis was 46.7%（7/15）.The detection rate of Salmonella class II integraton was 17.4%（4/23）,and the detection rate of class II integraton of Proteus mirabilis was 53.3%（8/15）.The results showed that the carrier rate of integraton of isolated bacteria was positively correlated with drug resistance,and the resistance rate of integraton positive isolates was significantly higher than that of integraton negative isolates.23 strains of Salmonella and 15 strains of Proteus mirabilis were selected for ligation test,21 strains of Salmonella and 10 strains of Proteus mirabilis were screened,a total of 4 strains of Salmonella and 2 strains of Proteus mirabilis were successfully engaged,and the resistance genes of aad A2,ant（3’’）-Ia,aph3-IIa,Flor,qnr S,sul I,tet A,and bla TEM were detected after successful bonding.The remaining 2 strains of Salmonella（1 strain containing NDM-1resistance genes）and 1 strain of Proteus mirabilis did not detect resistance genes.The stability test of 3 strains of positive transconjugants,carrying known drug resistance genes showed that drug resistance genes could be transmitted through plasmids.After 100 generations,aad A2,ant（3’’）-Ia,aph3-IIa,Flor,qnr S,sul I,tet A and bla TEM resistance genes were not lost,these resistance genes showed a long term stable inheritance even under no antibiotic selection pressure. |
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