TitleDevelopment of a rapid method to quantify Salmonella Typhimurium using a combination of MPN with qPCR and a shortened time incubation.
Publication TypeJournal Article
Year of Publication2017
AuthorsKim, SAe, Park, SHong, Lee, SIn, Ricke, SC
JournalFood Microbiol
Date Published2017 Aug
KeywordsAnimals, Bacterial Load, Colony Count, Microbial, Food Microbiology, Limit of Detection, Microbiota, Poultry, Real-Time Polymerase Chain Reaction, Salmonella typhimurium, Sensitivity and Specificity, Time Factors

A novel method was developed for the specific quantification of S. Typhimurium using a most-probable-number (MPN) combined with qPCR and a shortened incubation time (MPN-qPCR-SIT). For S. Typhimurium enumeration, dilutions of samples were transferred into three wells on a microtiter plate and the plate was incubated for 4 h. The S. Typhimurium presence in the wells was identified using a qPCR and populations were determined based on an MPN calculation. The R between the MPN-qPCR-SIT and conventional MPN exhibited a high level of correlation (0.9335-0.9752), suggesting that the MPN-qPCR-SIT offers a reliable alternative method for S. Typhimurium quantification. Although plating and qPCR were limited in their ability to detect low levels of S. Typhimurium (e.g. 0.18 log MPN/ml), these levels could be successfully detected with the MPN-qPCR-SIT. Chicken breast samples inoculated with S. Typhimurium were incubated at 0, 4, and 24 h and incubated samples were subjected to microbiome analysis. Levels of Salmonella and Enterobacteriaceae increased significantly with incubation time. The obvious benefits of the MPN-qPCR-SIT are: 1) a further confirmation step is not required, 2) the detection limit is as low as conventional MPN, but 3) is more rapid, requiring approximately 7 h to simultaneously complete quantification.

Alternate JournalFood Microbiol.
PubMed ID28400022