A local bakery advertised nut-free cakes after installing a building addition dedicated to nut-allergen-free orders. The owner purchased new mixers, utensils, pans, and other equipment to prepare goods for all nut-allergen-free orders. Business was so good in both sides of his operation that the owner had to hire an assistant pastry chef.

One of the orders for a Saturday pick-up was a nut-free seven-layer dobos torte for a birthday party. Mr. Thomas, who placed the order, was explicit in stating his wife had a highly sensitive nut allergy and asked if this would be a problem for the bakery. The owner was firm in his guarantee that his separate baking area was completely nut-free and his pastry chef could handle the order.

Before panning the dobos torte the assistant pastry chef ran out of parchment paper. Because the batter was ready to pour into sheet pans, she went into the main bakery and got parchment paper from the production area. Once baked, the layers were cooled and assembled with a chocolate butter cream and then held in a common refrigeration area for pick up orders.

On Monday, Mr. Thomas was irate when he called the owner to complain that his wife had an anaphylactic reaction to the torte and had to be rushed to the hospital in the middle of her party.

Which pathogen caused theillness?