Salmonella can survive the food preparation process and even
in mayonnaise kept at 4 C. In addition, Salmonella can grow
faster at room temperature. The fact that mayonnaise is a high fat
product, which could reduce the infecting dose of Salmonella,4
could explain the sharp increase in cases in a short time. E. coli
bacteria found in the ingredients were likely a contaminant due to
the poor personal hygiene of the food-handlers during bread
preparation.