Detection of genus Salmonella and serogroups A, B, C1, D and (Vi) capsular producing strains using multiplex polymerase chain reaction (PCR) method from stool

In many countries, Salmonella is the leading cause of food-borne outbreaks and infections. A multiplex PCR (mPCR) for the detection of genus Salmonella and serogroups A, B, C1, D and capsular (Vi) producing strains from swabs of stool samples was developed. In the mPCR, primers for invasion (invA), O (prt, tyv, rfbj, wzxC1) and Viantigen genes (Vi) and internal amplification control primers were used. The results showed that all tested Salmonella serotypes were accurately identified by the assay, without nonspecific amplification except Salm. derby and Salm. saint Paul. Representative serogroups were used to artificially inoculate stool samples. The different serogroups were detected by mPCR after overnight pre-enrichment of stool swab in buffered peptone water with a detection limit of Salmonella cell suspension of 4 cfu/ g stool. The developed mPCR assay provides specific detection of genus Salmonella and serogroups A, B, C1, D and Vi positive strains directly from stool swabs. The developed method for Salmonellaserogroup identification is rapid, easy and less subjective methods. This could be of great use by any facility that lacks the expensive typing sera and expertise needed for conventional serotyping.   Key words: Salmonella, multiplex PCR, stool, molecular serotyping, somatic antigen.