The Epidemiological Study Of Antimicrobial Resistance And Plasmid-mediated Quinolone Resistance Genes In Salmonella Isolated From Animal

Salmonella is common zoonotic pathogen and plays an important role in clinical medicine, veterinary medicine and public health. Severe antimicrobial resistance of bacteria was caused by the overuse and abuse of quinolones in husbandry. Informations from the antimicrobial sensitivity test and molecular epidemiological study of plasmid-mediated quinolone resistance genes in Salmonella can learn mergence and dissemination of resistant genes, and guide the rational use of antimicrobial agents.316 Salmonella isolates from 2003 to 2010 year in different animal were tested by biochemical and serological methods, twelve serogroups of Salmonella were detected, including S. Pullorum 58.9%(186/316),S.Fyris 7.9%(25/316) and S. Give 7.9%(25/316).Antimicrobial susceptibility of Salmonella to 20 kinds of antimicrobial agents was examined by using the broth microdilution method. The results indicated that except the resistant rate of Cefazoliin was 8.2%, the resistant rates of other antimicrobial agents were above 10%:Nalidixic acid, Sulfamethoxazole, Doxycycline, Tetracycline, Streptomycin, Amoxicillin/Clavulanic acid, Ampicillin, Florfenicol, Ceftiofurl,Gentamicin, Chloramphenicol, Norfloxacin, Kanamycin, Levofloxacin, Ofloxacin, Ciprofloxacin, Enrofloxacin, Amikacin,Lomefloxacin was 85.4%,85.4%,72.2%,60.8%,48.1%,41.1%,36.7%,29.4%,49.1%,28.5%,28.5%,19.9%,17.4%,15.8%,14.9%,12.3%,12.3%,12.0%,10.4%, respectively.The resistant rates of isolates from swines and cattles were higher than that from avians; the resistant rates of isolates from Sichuan Province and Guangdong Province were higher than that from Jiangxi Province and Henan Province. The resistant rate of isolates from Jiangsu Province was the lowest. Multi-resistance was severe among the Salmonella isolates, most isolates exhibited multidrug-resistance to 4 and 5 antimicrobial agents, furthermore the isolates from swines and cattles were resistance to 10 and 11 antimicrobial agents.By molecular epidemiological study of plasmid-mediated quinolone resistance genes of Salmonella isolates, qnrA,qnrC,qnrD,qnrS and qepA genes were not detected in 316 Salmonella isolates and aac(6')-Ib-cr,qrnB and oqxAB genes were detected. aac(6')-Ib-cr gene was the main, oqxAB gene was the first reported in Salmonella strains in China, and qnrB2 gene was the first detected in S. Give. GyrA,gyrB and par C mutations were detected in the Salmonella PMQR genes positive strains,except SYAP10-2 isolate were not detected QRDR mutations,the other were detected QRDR mutations.aac(6')-Ib-cr gene was located in the 182kb plasmid by southern blot. PFGE results showed that 53 strains of Salmonella showed five genotypes,50 strains including 25 S.Give and 25 S. Fyris belonged to two PFGE patterns, the other belonged to three patterns. 25 S.Give qnrB2 postive strains from different animals harboured the same PFGE pattern, which indicated that qnrB2 could be disseminated by vertical transmission; 25 S. Fyris strains with different resistant genes belonged to the same PFGE pattern, which demonstrated that 25 stains were same clone.In conclusion, Salmonella isolates from different animals were serious resistance to different antimicrobial agents, plasmid-mediated quinolone resistance genes can be transferred vertically. The results of study can provide informations for the prudent use of antimicrobial agents in veterinary clinic, and for preventing and controlling the dissemination of resistant bacteria and resistance genes.