Rapid Cultural Method to Detect Salmonella in Foods

The influence of reduced incubation time (8 h) on productivity of the Muller Kauffman tetrathionate and modified Rappaport broths incubated at 43°C was studied using naturally and artificially contaminated dry foods. Inoculation of selective enrichments from pre-enrichments and streaking on selective agar media were carried out on the same day, thus providing presumptive evidence of Salmonella one day earlier than with conventional cultural techniques. With modified Rappaport broth, the number of Salmonella -positive samples was the same after 8 and 24 h of selective enrichment. With Muller Kauffman tetrathionate, 3 false-negative results were obtained after 8 h of incubation. Salmonellae were detected at a level of less than 1 cell per 500 g of product (MPN).