This study aimed to develop a rapid method for detecting Salmonella in meat and poultry using a single-step enrichment followed by real-time PCR detection. 240 meat and poultry samples were tested using this candidate method and compared to the traditional culture-based USDA method. Results showed the candidate method had sensitivity comparable to the traditional method but with significantly faster results, allowing detection in as little as 24 hours versus the standard 7 days.

1. DEVELOPMENT AND EVALUATION OF A NEW RAPID METHOD FOR
DETECTION OF SALMONELLA IN MEAT AND POULTRY
Introduction
Despite control and prevention efforts, Salmonella infections arising from
contaminated meat and poultry continue to be a significant problem, with millions of
cases occurring each year. Conventional methods for the detection of Salmonella
can require up to seven days for a positive result and are not appropriate for routine
testing of large numbers of samples. Thus, the development and implementation of
rapid detection methods of Salmonella are among the most important food safety
tasks [1, 2].
The objective of this study was to develop a sensitive and rapid method for
Salmonella detection in meat and poultry, including raw ground beef, raw ground
chicken and chicken carcass rinses. This study included validation of a new
protocol based on single-step enrichment with Actero™ Salmonella Enrichment
Media followed by detection using the DuPont™ BAX® System Real-Time PCR
Assay for Salmonella.
Assay Principle
In total, 240 meat and poultry samples were tested according to the AOAC
INTERNATIONAL Methods Committee Guidelines for Validation of Qualitative and
Quantitative Food Microbiological Official Methods of Analysis [3]. The food
matrices were routinely spiked with laboratory Salmonella strains shown in Table 1.
AOAC Validation Protocols
Sergiy Olishevskyy1, Cathy St-Laurent1, Morgan Wallace2, Melissa Buzinhani1, Michael Giuffre3
1. McEntire J. et al. The public health value of reducing Salmonella levels in raw meat and
poultry. Food Prot Trends 2014, 34(6): 386–392.
2. Park SH. et al. Current and emerging technologies for rapid detection and characterization
of Salmonella in poultry and poultry products. Food Microbiol 2014, 38: 250–262.
3. AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological
Methods for Food and Environmental Surfaces Official Methods of Analysis of AOAC
INTERNATIONAL, 19th Ed., Appendix J, AOAC INTERNATIONAL, Gaithersburg, MD.
4. USDA-FSIS. 2014. Isolation and identification of Salmonella from meat, poultry,
pasteurized egg, and catfish products and carcass and environmental sponges. In:
Microbiology Laboratory Guidebook, Chapter 4.08.
Results
Conclusions
 The method developed for rapid detection of Salmonella
in meat and poultry samples shows the sensitivity
comparable to the traditional culture-based method with a
significant reduction in time-to-result.
 Using chromogenic agar plates individually selected for
each matrix tested allows to reinforce the results obtained
with the BAX System method or can be independently
applied for culture method of Salmonella detection.
References
1FoodChek Laboratories Inc., St-Hyacinthe, Quebec, Canada 2DuPont Nutrition & Health, Wilmington, Delaware, USA 3FoodChek Systems Inc., Calgary, Alberta, Canada
Table 1. Food Matrices and Inoculating Microorganisms
Table 2. Salmonella Recovery from Chicken Carcass Rinses Using Actero™
Salmonella Supplemented with Malachite Green
Table 3. Effect of Malachite Green on Recovery, Growth and Detection of
Salmonella in Ground Chicken Enriched with Actero™ Salmonella
Table 4. Culture Detection of Salmonella in Ground Chicken Enriched with
Actero™ Salmonella for 14 hours
A total of 240 meat and poultry samples were examined by the candidate method in
comparison with the USDA-FSIS MLG 4.08 reference method [4].
The main parameters of enrichment, including sample dilution, incubation
temperature and selective supplements, were optimized to allow specific recovery
and intensive growth of Salmonella in the presence of abundant competitive flora.
Malachite green, also known as an antimicrobial agent, was chosen to supplement
Actero™ Salmonella medium. Effect of different concentrations of malachite green
on recovery and growth of Salmonella in enriched samples shown in Tables 2 and
3. As a result, 50.0 mg/L malachite green were used for ground beef and ground
chicken samples while only 12.5 mg/L green malachite was recommended for
chicken carcass rinses (see Table 2). Next day confirmation of Salmonella in
enriched samples was also optimized using different commercial selective agars
(Table 4).
The method comparison study results for meat and poultry samples are shown in
Table 5.
Table 5. Method Comparison Study Results
Study Design