Inadequacy of Selective Plating Media in Field Detection of Salmonella

Salmonella is an important human enteropathogen associated with poultry. Poultry is routinely analyzed for Salmonella by industry, regulatory, and research laboratories. Effectiveness of selective plating media is critical to Salmonella laboratory analysis. Many media routinely used in the food microbiology laboratory were developed for all Gram-negative human enteric pathogens encountered in a clinical laboratory, rather than for Salmonella alone. The presence of extraneous, non-Salmonella bacteria make the recognition of Salmonella on these plates very difficult. This, more than any other factor, contributes to poor performance of a medium. Primarily because of the poor performance of many selective agars in detecting Salmonella from non-clinical samples, food microbiology laboratories usually use two or more plating media to reduce false negative results.