title: Development of a rapid method to quantify Salmonella Typhimurium using a combination of MPN with qPCR and a shortened time incubation.
abstract: 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 R2between 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.
authors.affiliation: Center for Food Safety, Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
authors.forename: Sun Ae
authors.initials: SA
authors.lastname: Kim
authors.affiliation: Center for Food Safety, Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
authors.forename: Si Hong
authors.initials: SH
authors.lastname: Park
authors.affiliation: Center for Food Safety, Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
authors.forename: Sang In
authors.initials: SI
authors.lastname: Lee
authors.affiliation: Center for Food Safety, Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA. Electronic address: sricke@uark.edu.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Ricke
mesh_terms: D000818:Animals; D058491:Bacterial Load; D015169:Colony Count, Microbial; D005516:Food Microbiology / Q000379:methods*; D057230:Limit of Detection; D064307:Microbiota; D011200:Poultry / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013997:Time Factors
keywords: Detection; Quantification; Rapid; Salmonella Typhimurium; Simple