Enumeration of Salmonella in compost material by a non-culture based method

Accurate enumeration of Salmonella spp. is important for assessing whether this pathogen has survived composting. Recent literature has reported that enumeration of Salmonella spp. using standard microbiological methods has a numbers of disadvantages, particularly the time taken to obtain a result. This research is an attempt to develop a rapid, low-cost detection method that is quantitative, highly sensitive and target specific. This paper reports the development of a DNA fragment that can be used to quantify Salmonella spp. by competitive polymerase chain reaction (cPCR) targeted at the invA gene of Salmonella (PCR primers that target the invA gene are reported to have very high specificity for Salmonella strains). It is shown that cPCR, which could be completed in 5 hours, could quantify the number of copies of the Salmonella invA gene in a sample solution.