Influence of Enrichment Incubation Time on the Isolation of Salmonella

The optimum incubation times for Salmonella enrichment cultures were determined by inoculation of enrichment broths onto plating media after 24 hours at 37 C, after 48 hours at 37 C, after a 3-day delayed secondary enrichment (DSE), and after a 5-day DSE procedure. The results showed a step-wise increase in Salmonella isolations with the longer incubation times. Inoculation of the enrichment broths onto plating media after 24 hours incubation followed by a 5-day DSE made possible the detection of 96% to 98% of the Salmonella-positive samples and was the best combination of conditions.