Detection and identification of salmonellas from poultry-related samples by PCR

Abstract

A polymerase chain reaction (PCR) assay was developed for the generic detection of Salmonella sp. and the identification of S. Enteritidis (SE), S. Gallinarum (SG), S. Pullorum (SP) and S. Typhimurium (ST) in material collected in the field from poultry. The specificity and sensitivity of the assay combined with Rappaport–Vassiliadis selective enrichment broth (PCR–RV) were determined, and field samples were analyzed to verify the validity of the method application. Specificity of the assay was tested using 29 SE, 11 SG, 10 ST and 10 SP strains, along with 75 strains of 28 other Salmonella serovars and 21 strains of other bacterial genera. The assay was 100% specific for Salmonella detection and ST identification. The primer pair for SE, SG and SP also detected S. Berta. PCR detection limits for Salmonella at the genus level were 2 ST, 8 SE, 1.1×10 3 SG and 1.8×10 5 SP cells. At the serovar level, detection limits were 7 ST, 1.2×10 3 SE, 4.4×10 7 SG and 1.8×10 6 SP cells. At the genus level, PCR–RV detected ≈128% more positive field samples than the standard microbiological techniques and results were ready in 48 h instead of 7 days. PCR–RV method is diagnostic of Salmonella at the genus level and ST at the serovar level, although other tests are needed to identify SE, SG and SP to serovar level.