Evaluation of staA, viaB and sopE genes in Salmonella detection using conventional polymerase chain reaction (PCR)

Typhoid fever is caused by the bacteria Salmonella enterica subspecies enterica serovar Typhi ( S . Typhi) and remains a significant health problem in many developing countries. The lack of adequate diagnostic capabilities in these poor resource settings have contributed greatly in making typhoid fever endemic in these regions. Reliable and inexpensive diagnostic tests are needed to improve the management of this disease burden.  This study evaluated the ability of staA, viaB and sopE genes to detect Salmonella spp. Conventional polymerase chain reaction (PCR) amplification of staA , viaB and sopE genes of Salmonella was used to detect and differentiate between the three most prevalent Salmonella spp. in Kenya ( S . Typhi, S. Typhimurium and S. Enteritidis). The staA primers (StaA-Forward / StaA-Reverse) and viaB primers (vi- Forward / vi- Reverse) were found to be specific only for the different strains of S . Typhi, producing PCR products of 585 bp and 540 bp respectively. No amplification was observed with S. Typhimurium, S. Enteritidis, E . coli and S . boydii bacterial strains. The sopE primers (SopE- Forward / SopE- Reverse) was demonstrated to be specific for all Salmonella spp. producing a 465 bp PCR product with no amplification observed with the E . coli and S . boydii bacterial strains. Conventional PCR using these staA and viaB primers for detection of S . Typhi shows great potential for diagnosis of typhoid fever however, further studies need to be carried out with actual food samples and human samples (blood, stool or saliva) to determine the effectiveness of this method in the detection of common Salmonella spp. in Kenya.