Abstract: A multiplex PCR assay was developed for the effective and simultaneous detection of Salmonella spp. and Staphylococcus aureus in quick-frozen foods. Optimum amplification system and genomic DNA extraction method were established. Salmonella spp. and S. aureus could be simultaneously detected with 100% specificity under the optimum conditions of 60 ℃, 200 nmol/L and 35 for annealing temperature, primer concentration and number of amplification cycles, respectively. Among three tested genomic DNA extraction methods, the highest purity of genomic DNA could be obtained by kit-based method, and the limits of detection were 31 and 26 DNA copies/reaction for both pathogens, respectively. When the mulitplex PCR assay was applied in artificially contaminated quick-frozen dumpling, both pathogens could be simultaneously detected with detection limit as low as 100 CFU/g after 4 h of bacterial enrichment. Taken together, considering specificity, sensitivity and effectiveness, the multiple PCR assay has a high potential in pollution condition investigation and effective detection of Salmonella and S. aureus in quick-frozen foods.

Key words: quick-frozen food, multiplex polymerase chain reaction assay, detection, Salmonella, Staphylococcus aureus