Onset of symptoms occurs about 12 hours after ingestion of the contaminated food with symptoms lasting 2 to 3 days. The disease is generally self-limiting. The isolation and identification of Salmonella can be a very time-consuming and expensive process and includes the use of a number of selective and differential media. Foods should not be released by the manufacturer until declared free of salmonellae. This requires holding the product, at consumer expense, for a protracted period of time.
Research continues to develop rapid, reliable methods to detect salmonellae.
The method traditionally used by the Food and Drug Administration begins with a nonselective enrichment in lactose broth. A selective broth enrichment follows on the next day. On the third day, the selective enrichment is streaked onto several different selective-differential plating media to initiate the isolation of any salmonellae present. If the results of the TSI Agar and LIA indicate the probability of Salmonella , the BHI Broth culture is employed in the serological confirmation of the presence of the organism with the use of polyvalent flagellar antisera. Tests for identity of cell wall antigens may also be done, using cells from the TSI Agar.