Development of a PCR test system for specific detection of Salmonella Paratyphi B in foods.
Salmonella enterica serotype Paratyphi B is a globally distributed human-specific pathogen causing paratyphoid fever. The aim of this study was to develop a rapid and reliable polymerase chain reaction (PCR) assay for its detection in food. The SPAB_01124 gene was found to be unique to S. Paratyphi B using comparative genomics. Primers for fragments of the SPAB_01124 gene and the Salmonella-specific invA gene were used in combination to establish a multiplex PCR assay that showed 100% specificity across 45 Salmonella strains (representing 34 serotypes) and 18 non-Salmonella strains. The detection limit was 2.2 CFU mL(-1) of S. Paratyphi B after 12-h enrichment in pure culture. It was shown that co-culture with S. Typhimurium or Escherichia coli up to concentrations of 3.6 × 10(5)  CFU and 3.3 × 10(4)  CFU, respectively, did not interfere with PCR detection of S. Paratyphi B. In artificially contaminated milk, the assay could detect as few as 62 CFU mL(-1) after 8 h of enrichment. In conclusion, comparative genomics was found to be an efficient approach to the mining of pathogen-specific target genes, and the PCR assay that was developed from this provided a rapid, specific, and sensitive method for detection of S. Paratyphi B.
College of Food Science and Technology, Nanjing Agricultural University, Key Laboratory of Food Processing and Quality Control, Ministry of Agriculture of China, Nanjing, China.
Ligong
L
Zhai
Qian
Q
Yu
Xiaomei
X
Bie
Zhaoxin
Z
Lu
Fengxia
F
Lv
Chong
C
Zhang
Xiaohan
X
Kong
Haizhen
H
Zhao
D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005516:Food Microbiology / Q000379:methods*; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D012484:Salmonella paratyphi B / Q000235:genetics / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
D017931:DNA Primers; D004269:DNA, Bacterial
Salmonella Paratyphi B; comparative genomics; detection; multiplex PCR