Listeria spp. and Listeria monocytogenes contamination in ready-to-eat sandwiches collected from vending machines

Ready-to-eat (RTE) food is characterised by a
long shelf-life at refrigerated temperature and
can be consumed as such, without any treatment.
The aim of the work was to evaluate the
presence of Listeria spp. and Listeria monocytogenes
in RTEs collected from refrigerated vending
machines placed in hospital environment
and accessible to the hospitalised patients. In 4
different sampling, 55 RTEs were collected from
vending machines of six hospitals located in different
areas of Sardinia region. All the samples
were characterised by similar manufacturing
process, such as the use of modified atmosphere
packaging and belonged to 5 different producers.
Listeria spp. was not countable using the enumeration
method in all of the analysed samples.
Using the detection method, Listeria spp. was
recovered from 9 sandwich samples.
Interestingly, 3 of these samples (5.5%) made by
the manufacturer, were positive for L. monocytogenes
contamination. The risk related to the L.
monocytogenes presence in RTEs proportionally
increases when food is introduced in susceptible
environments, such as hospitals and consumed
by susceptible people. Although the RTEs
analysed showed values that complied with the
European microbiological criteria for foodstuffs,
the availability of these products in a susceptible
environment should be carefully checked.
Therefore, in order to limit the possible exposition
to L. monocytogenes, more information on
the risk related to RTE consumption should be
provided to the hospitalised patients.