Abstract
Culture-based detection is still considered as the standard way for detection of Salmonella in foods, although molecular methods, such as viability PCR (vPCR), have been introduced to overcome some disadvantages of traditional culture methods. Despite the success of the vPCR methodology, the problem of false-positive results is a major drawback, especially when applied to environmental samples, hindering the interpretation of the results. To improve the efficiency of vPCR, many approaches have been introduced by several authors during the last years. In the present work, the combination of PEMAX dye, double tube change, and double photo-activation step was established as a strategy to improve vPCR protocol. By combining these approaches, we developed an improved sample treatment protocol able to neutralize DNA signals of up to 5.0×107 dead cells/sample from both pure culture and artificially contaminated food samples. Our results indicate that vPCR can work reliable and has a potential for high throughput detection of live Salmonella cells in food samples, minimizing false-positive signals.
Highlights
Salmonella belongs to one of the most common zoonotic pathogens causing a notable number of foodborne outbreaks and product recalls
The selectivity of 100 μM PEMAX was tested on serial dilutions of live Salmonella cells (5.0×107 to 5.0×103 cfu) mixed with 5.0×107 dead cells
The polymerase chain reaction (PCR) efficiency with serial dilutions of pure DNA was only slightly higher with 98.27% (S1 Fig). These results indicate that PEMAX was able to eliminate PCR signals of 5.0×107 dead Salmonella cells without affecting the PCR efficiency
Summary
Salmonella belongs to one of the most common zoonotic pathogens causing a notable number of foodborne outbreaks and product recalls. The most important food vehicles for foodborne Salmonella outbreaks were eggs and egg products, pig meat and products thereof, as well as bakery products [1]. In order to improve food safety related to Salmonella, it is important to carry out preventive quality controls based on standard detection technologies. According to several governmental regulations or recommendations, Salmonella must not be detectable in 25 g of food. The culture-based detection method is considered as the ideal way for detection of microorganisms.
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