|Cox, Nelson - Nac|
Submitted to: Compendium of Methods for the Microbiological Examination of Foods
Publication Type: Book / Chapter
Publication Acceptance Date: 2/3/2013
Publication Date: 3/1/2013
Citation: Cox Jr, N.A., Frye, J.G., Mcmahon, W., Jackson, C.R., Richarson, L.J., Cosby, D.E., Mead, G.C., Doyle, M.P. 2013. Salmonella. Compendium of Methods for the Microbiological Examination of Foods. Available: http://ajph.alphapublications.org/doi/book/10.2105/MBEF.0222. Interpretive Summary:
Technical Abstract: Salmonella are facultative anaerobic Gram-negative non-spore forming rods belonging to the family Enterobacteriaceae. Salmonellosis is a zoonotic and foodborne illness that is usually transmitted by the fecal-oral route estimated to be responsible for 1.4 million cases of human infections in 2009 in the U.S. at a cost of 2.6 billion of dollars in medical fees and lost productivity. Control of salmonellosis is reliant upon implementation of adequate laboratory quality control programs in the food industry requiring a continuing need for microbiological analysis for monitoring, validation and verification. In this book chapter, major aspects of Salmonella culture methodology primarily adapted from the Official Analytical Chemists International (AOAC) have been presented including a historical background of culture methods for salmonellae, sampling of numerous food items such as red meat, poultry, mild and eggs, and bacterial isolation and identification. For an organism that is often present in foods in only low numbers, and may be unevenly distributed, the sample type, size, location, and number per lot are key considerations, while results may be further influenced by the ways in which samples are collected, transported, stored, and sub-sampled. There are also methodological factors in sample testing that may influence the isolation rate and prevalence of different Salmonella serovars around the world. These include the nature of the media used for selective enrichment and plating, and the number of colonies from each sample that are picked for serovar determination. Above all, there is a need for wider use of standardized methods that are accepted internationally or methods shown to be equivalent in performance. Like other cultural methods, it is relatively laborious and time-consuming and therefore more modern, rapid methods will also be considered in this chapter. Rapid methods including use of indicator media, immunological detection, detection by conductance, Polymerase Chain Reaction (PCR) of specific DNA sequences, and microarray hybridization have also been described. New technologies for the identification of specific Salmonella serotypes or genotypes are currently under development utilizing techniques such as high thoughput sequencing (HTS) and mass spectral analysis. As these methods are improved, they may soon be inexpensive enough for application to food safety monitoring.