[Comparison study of enrichment-PCR and traditional method for detection of Salmonella in poultry]

To compare the sensitivity, specificity and timeliness of Salmonella in poultry detected by enrichment-PCR and traditional method.

Salmonella specific primers (PsalF-PsalR) were chosen on the basis of invA gene. PCR method was developed and its specificity was proved by 30 Strains of Salmonella standard and isolates,and 18 strains of non-Salmonella. Refering to GB4789.4--2010, artificially contaminated experiment was done,six artificially-inoculated samples containing final concentration of salmonella CMCC50041 (1, 10, 10(2),10(3), 10(4), 10(5) and 10(6) CFU/25 g poultry samples) were preparated respectively, meanwhile one sample without inoculation was as control of background value. All the samples were incubated at 37 degrees C for 0, 4, 8, 12 and 18 h, and Iml of culture solutions were taken from the samples to extract DNA, respectively. PCR and traditional methods were applied to detect Salmonella bacteria. Sixteen samples of retail whole poultry were collected from markets in Beijing and detected by the above two methods after enriching for 12 h in SC at 37 degrees C.

PCR method established was stable and specific, as 30 Salmonella were detected positive and 18 non-Salmonella were negative. PCR detection limit for artificially contaminated samples after enriching for 12h was 1 CFU/25 g sample. Traditional method detection limit was 10 CFU/25 g samples. The time limits of enrichment-PCR were 4-6 days, shorter than those of traditional method. The positive rate out of total 16 market-sold samples was 43.75% (7/16) for enrichment-PCR,while the rate was 31.25% (5/16) for traditional method.

Enrichment-PCR was simple, rapid, sensitive and specific in comparition with traditional method. It could be applied in fast diagnosis of food poisoning and actual food samples screening.