Abstract:
Serovars of the bacterium Salmonella enterica are important worldwide causative agents of bacterial
food poisoning. Of more than 1500 serovars of this species; Salmonella Enteritidis, Salmonella
Typhimurium and Salmonella Gallinarum are the most important serovars affecting human health and
poultry industry. They cause great economic losses both due to their implication in animal welfare and
their ability to contaminate poultry food products forming a serious food safety problem. Early
detection and typing of these serovars is essential for food safety regulations and poultry industry. The
current techniques to detect and serotype these serovars are time consuming and require technical
expertise. The aim of this work was to develop a practical PCR-based method that can detect and
distinguish the above mentioned 3 serovars. Genomic sequence data of Salmonella Gallinarum,
Salmonella Enteritidis and Salmonella Typhimurium was used through NCBI database (as of Month
2015). Intensive comparative genomic analysis was conducted to identify unique segments for each
serovar. The identified unique segments were used as specific markers to design 3 close nested PCR
assays that can detect and distinguish the three serovars. The detection specificity of the PCR assays
were tested using a wide range of Salmonella enterica serovars. The detection sensitivity of the three
PCR tests was examined using 10 fold serial dilutions of the control DNAs. The analysis revealed
unique segments for each serovar that can serve as specific genetic markers. PCR-primers for each
unique segment produced the specific amplicon for each serovar. The developed close nested PCR
techniques showed amplification signal of as low as (0.03 ng- 3 pg) DNA, which is 100-fold more
sensitive than traditional PCR protocols. Three of the most important Salmonella enterica serovars,
which are associated with poultry health and human food poisoning were detected and typed by a very
sensitive PCR technique. The developed PCR can be used as a routine test to manage and control the
poultry health and safety of poultry products.
