Development of a Simple, Sensitive, and Cost-effective PCR Method for Detection of Salmonella in Environmental Samples

Introduction: Salmonella is one of the leading foodborne pathogens of public health concern, causing millions of foodborne illnesses worldwide. Polymerase chain reaction (PCR) is widely used in the routine detection of foodborne human pathogens; however, challenges remain in overcoming PCR inhibitors present in environmental sample matrices.

Purpose: The objective of this study was to develop a simple, rapid, sensitive, and cost-effective PCR method for detection of Salmonella in environmental samples.

Methods: Six DNA template preparation methods, including direct boiling, with or without pre-spin, multiple washing, and two commercial DNA extraction kits, were compared using pure overnight cultures of Salmonella and those spiked with background microflora from enriched  soil, cattle feces, and pecan samples. The effect of different amplification facilitators such as, bovine serum albumin (BSA), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and gelatin on PCR sensitivity was also evaluated.  

Results: Pre-spin of sample matrices in combination with the addition of 0.4% BSA and 1% PVP in the PCR mix was the most simple, sensitive, and cost-effective PCR method for detection of Salmonella. In the presence of 3 x 10⁹ CFU/ml background microorganisms in enriched soil or fecal samples, 40 CFU Salmonella per reaction can be detected. This sensitivity was similar to that of pure culture tested.

Significance: The developed method is simple, rapid, sensitive, and cost-effective, with broad applicability for processing large numbers of environmental samples for PCR detection of Salmonella.