title: [Rapid simultaneous detection of Salmonella and Shigella using modified molecular beacons and real-time PCR].
abstract: OBJECTIVE
  Dual detection of Salmonella and Shigella using modified molecular beacons and real-time PCR was developed. The established method was applied to rapid diagnosis of Salmonella and Shigella' food poisoning, and for routine monitoring programs.
  
  
  METHODS
  Two sets of primers were designed based on the core sequence of invA gene and ssaR gene published on GenBank to detect Salmonella, and ipaH gene were selected to detect Shigella. Three corresponding modified molecular beacons labeled with different fluorophors were designed. The molecular beacons and primer sets were tested against numerous strains from 55 different bacterial species. Then the two assays were combined to establish the dual real-time PCR assay, and were applied to the food poisoning diagnosis and surveillance.
  
  
  RESULTS
  For the modified molecular beacons-based dual real-time PCR assay, the sensitivity achieved was 69-93 fg/microl, 32-64 CFU/ml or 1-2 CFU/PCR reaction. There was no cross-reaction with other bacteria served as control. The dual real-time PCR assay was used to detect 134 Salmonella strains and 67 Shigella strains but no false signals were observed. 1100 food poisoning samples were tested with 569 Salmonella and 42 were Shigella identified by real time PCR. Among the positive samples, 551 were detected Salmonella and 41 were Shigella by traditional culture method. The overall test could be finished within 2 hours to one day starting from sample preparation.
  
  
  CONCLUSIONS
  The modified molecular beacons-based dual real-time PCR assay was rapid, sensitive, and specific. It could be applied to the rapid diagnosis of Salmonella and Shigella' food poisoning.
authors.affiliation: Shenzhen Center for Disease Control and Prevention, Shenzhen 518020, China.
authors.forename: Xiao-lu
authors.initials: XL
authors.lastname: Shi
authors.forename: Qing-hua
authors.initials: QH
authors.lastname: Hu
authors.forename: Jia-feng
authors.initials: JF
authors.lastname: Zhang
authors.forename: Qing-ge
authors.initials: QG
authors.lastname: Li
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.forename: Yi-man
authors.initials: YM
authors.lastname: Lin
authors.forename: Zhi-xiong
authors.initials: ZX
authors.lastname: Zhuang
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Liu
authors.forename: Shun-xiang
authors.initials: SX
authors.lastname: Zhang
mesh_terms: D017931:DNA Primers; D004405:Dysentery, Bacillary / Q000175:diagnosis*; D005798:Genes, Bacterial; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D012475:Salmonella / Q000235:genetics*; D012478:Salmonella Food Poisoning / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D012760:Shigella / Q000235:genetics*
chemical_list: D017931:DNA Primers