no detailed records on the manufacturing process were available to
allow for the retrospective identification of such a critical processing
step.
Interestingly, SE was detectable in three of the five different types of
ice-cream, only: vanilla, pistachio and chocolate, with all three
harbouring high amounts of CPS, too. In contrast, SE was detectable
neither in strawberry nor in yoghurt-lemon ice-cream. This allows for
the speculation, that a common ingredient was used, possibly being
contaminated with either SE or CPS. In case of the latter, the
manufacturing process must allow for growth of CPS and subsequent
SE production. The different types of ice-cream were produced on
several days prior the christening party all by use of the same icecream-maker
device. The two fruit-containing ice-cream types were
produced first, while the three types of milk ice-cream (chocolate,
vanilla, and pistachio) were produced from pasteurized milk as ground
mass. But also Ice-cream with fruit components contains milk or milk
products in general. Therefore, it cannot be excluded that the
pathogen was introduced via contaminated milk. As neither recipes
for the different types of ice-cream, nor details about the origin of its
components were available at the time of investigation a common
ingredient could not be identified. Despite the possible introduction
via an ingredient, it might also be assumed that the ice-cream was
contaminated through the used equipment. S. aureus is capable of
developing biofilms on food-processing surfaces, a pathway leading to
cross contamination of food (Vázquez-Sánchez et al., 2013). However,
as the equipment used for the manufacturing and handling of ice-