A Survey Of Contamination With Salmonellas In Broiler Chickens In Hefei And Analysis Of Characteristics Of Salmonella

Objective: To survey contamination of Salmonellas in broiler during the productionand processing course in Hefei city; to understand the serotype distribution, drugresistance spectrum of the antibiotics and the pulsed field gel electrophoresis moleculartyping; to provide fundamental data for Hefei local food security as well as scientificfoundation to strengthen the public health of Hefei.Methods: Use anal swab method and carcass rinsing method to examine theSalmonellas in45broilers and45broiler carcasses of Hefei10broiler farms and14slaughter plants in July2010-September2010. Conduct biochemical identificationtowards the suspected bacterial colonies indicated by the color plate of the CHROMagar Salmonella. Aiming at the invA and hilA genes of the Salmonella, use PCRmethods for review of those suspected Salmonella identification. Apply the χ2test ofbroilers and broiler carcass Salmonella in vivo differences to determine the correlationbetween the bacterial strains. Adopting Thai S&A’s Salmonella diagnostic antiserarecommended by the World Health Organization for those positive bacterial strains, useslide agglutination method to determine the Salmonella serotypes of the isolated12Salmonella strains. Use disk diffusion method recommended by the Committee forClinical Laboratory Standards (the Clinical and Laboratory Standards Institute, CLSI)for susceptibility testing of Salmonella. Use U.S. CDC recommended pulsed-field gel electrophoresis to determine the DNA of Salmonella restriction maps and analyze theelectrophoresis patterns by BioNumerics to determine their pulsed-field gelelectrophoresis (PFGE) molecular typing.Results: No bacterial strain was detected in the45broiler live specimens, the detectionrate0.0%;12Salmonella strains were detected in the45broiler carcass specimens, thedetection rate26.7%. Review by PCR testing indicated that the invA, hilA gene carrierrate was100.0%among the12Salmonella strains isolated in this experiment. CarcassSalmonella detection rate was significantly higher than broilers in vivo (χ2=13.846, P<0.001). Among the12isolated Salmonella strains, there were3serotypes.9wereIndiana Salmonella,2were Salmonella typhimurium and one was Salmonella enteritidis.The drug resistance rates of the12Salmonella strains to15kinds of antibioticsgentamicin, amikacin, chloramphenicol, nalidixic acid, ciprofloxacin, levofloxacin,tetracycline, ampicillin, amoxicillin-clavulanate acid, cefepime, cefotaxime, ceftriaxone,cefoxitin, ceftazidime, and cotrimoxazole were:75.0%,16.7%,75.0%,83.3%,75.0%,75.0%,75.0%,83.3%,25.0%,58.3%,58.3%,58.3%,8.3%,0.0%,66.7%. The overalldrug resistance rate was83.3%(10/12). The multi-drug resistance rate was83.3%（10/12）. Among them two strains of S. typhimurium were sensitive to all15antibiotics. Seven types of PFGE banding patterns were identified out of the12Salmonella strains, one for the two Salmonella typhimurium,5for the9IndianaSalmonella. Salmonella serotypes of the same serum type are substantially located inthe same large cluster. The bacterial strains of the same PFGE banding patter indicatedsimilar performance on drug resistance. Conclusion: The Salmonella examination results indicated in the rectal swab and thecarcass rinsing samples of the broilers were statistically significant with the detectionrate of the carcass rinsing samples significantly higher than the rectal swab samples. Inthe meanwhile, the serotypes, drug sensitivity and genotype of the Salmonellas in theexamined broilers indicated evident diversity. In addition, the bacterial strains werestrongly drug resistant. The bacterial strains of the same PFGE banding pattern hadsimilar drug resistant spectrum.