Controlling Cross-Contamination
Controlling Listeria monocytogenes in retail environments
fi rst begins with preventing cross-contamination. To
prevent the contamination of food prior to delivery, it is
recommended that establishments:
• work with reputable vendors who operate under Hazard
Analysis and Critical Control Point or HACCP systems
and/or are inspected by federal, state, or local agencies;
• require vendors to provide letters of guarantee (LOG)
and/or certifi cates of analysis (COA) that indicate products
have been tested and are free of pathogens, if possible.
To prevent Listeria monocytogenes cross-contamination
within the retail establishment, especially between raw and
RTE food preparation areas, develop fl ow plans for foods
from receiving, to storage, through processing or preparation,
and fi nally to sale. As part of the fl ow, establishments
should make an eff ort to take the following precautions in
designing fl ow plans:
• Separate raw and RTE preparation areas. Raw meats
should not be prepared or processed in the deli preparation
areas. Preparation of raw chicken for the rotisserie or
raw fi sh for frying should be done in an area separate from
the deli and/or RTE food preparation area.
• Minimize traffi c between raw and RTE areas (Figure 12).
Raw foods such as raw meats, poultry, and seafood should
not be transported through RTE food areas such as the
deli. Th is approach is essential since there is a potential for
cross-contamination between the raw and RTE product.
Raw meats, poultry, and seafood also should be displayed
in a separate case, preferably away from the deli area or
physically separated by sturdy and cleanable dividers
within cases.
Figure 12. Minimize traffi c between raw and RTE areas by
implementing procedures that take into account the fl ow of
food during preparation.
• Physically separate raw and RTE products in refrigerated
display cases and refrigerated storage areas. Ideally,
raw and RTE foods should be displayed in separate cases.
When this is diffi cult, due to facility restraints, an eff ort
should be made to physically separate raw and RTE foods
with plastic barriers or containers
time, the risk for contamination of RTE food increases.
Th is approach is especially important since Listeria monocytogenes
can produce biofilms, or an invisible slime layer, on
surfaces.
In summary, numerous risk factors are associated with the
contamination and growth of Listeria monocytogenes in retail
establishments. Th ese factors need to be addressed to identify
control measures for an eff ective Listeria monocytogenes
prevention/control program.