Investigation On The Carrying Situation Of Salmonella From Pet Dogs And Food In Hefei And Analysis Of Their Antibiotic Resistance

Salmonella is a kind of important zoonotic pathogens that widely exist in humanbeings, livestock, pets and foods, etc. After eating feed contaminated with Salmonella,pet dogs may cause infection. It would be transmitted to human beings via pet dogs inthe process of close contact. Also, people may be infected with Salmonella by directcontact with contaminated feed, when people feed the dog. So as to constantly expandthe scope of the spread of Salmonella. Pet dogs and dog food, as a storage reservoir ofSalmonella, play an important role in the aspects of spread of Salmonella and itsimpact on human beings.The carrying situation of Salmonella from pet dogs and food in Hefei, theirantibiotic resistance, and the distribution and the mRNA expression levels ofantibiotic resistant genes were understood in this research.746anal swabs of pet dogsand404samples of dog food were collected in Hefei and detected by nationalstandards and polymerase chainreaction (PCR) method. Then their serotypes andantibiotic resistant phenotypes were identified by agglutination test and K-B discdiffusion method respectively, antibiotic resistant genes were detected by PCRmethod. Meanwhile, ESBLs-producing strains were tested by phenotypicconfirmatory tests recommended by CLSI. Two SYBR Green I Real-Timequantitative PCR methods were esTablelished for the detection of flor and sul2gene,respectively. And the mRNA expression levels of flor and sul2gene in differentstrains were detected and analysed by Real-Time quantitative PCR methods,respectively.Results of this study show that19strains of Salmonella were isolated and identified,with the positive rate as2.55%(19/746) and the superiority serotype as Salmonellaenteritis, from anal swabs of pet dogs, and10strains of Salmonella were isolated andidentified, with the positive rate as2.48%(10/404) and the superiority serotype asSalmonella derby, from samples of dog food. In the antibiotics susceptibility test,20kinds of antibiotics were choosed. It was the most extensive in resistance toAmoxicillin/Claw-lanic Acid (AMC) and Ampicillin (AMP), and the most sensitivein resistance to Cefoxitin (FOX) and Fosfomycin (FOM). The isolating rate ofmultiple antimicrobial resistant strains was31.03%, and the dominatingmultidrug-resistant spectrum was AMC-AMP-SXT-DOX.19kinds of drug resistance genes were detected by PCR method. The strA-B gene was the most prevalent withthe deteced rate of85.7%, and followed by blaPSEgene with the deteced rate of34.48%.6strains of ESBLs-producing Salmonella were tested by phenotypicconfirmatory tests. There were esTablelished that two SYBR Green I Real-Timequantitative PCR methods to detection of flor and sul2gene, with the minimumdetection limit as102copies/μL和103copies/μL, respectively. The mRNA expressionlevels of flor gene in the strains resistant to florfenicol including S8, S10, G8, G17and G19were higher than in the florfenicol-intermediate strain S7. The mRNAexpression levels of sul2gene in the strains resistant to florfenicol including S10, G8,G17and G19were higher than in the susceptible strain G6and G15. The studydemonstrated that there are different degrees of carry Salmonella in pet dogs and food.The antimicrobial resistance of the isolated strains was serious and ESBLs-producingstrains were discovered. The Real-Time PCR method esTablelished in the study isreproducible, specific, rapid and sensitive, which can replace ordinary PCR method todetect antimicrobial resistance genes. There are positively correlated relationshipbetween the resistance level of Salmonella and the mRNA expression levels ofantimicrobial resistance gene.