Biomedical Engineering Reference
In-Depth Information
contaminated in retail delis (Endrikat et al.
2010
; Pradhan et al.
2010
). A recent
USDA/FDA risk assessment concluded that implementing effective food safety
practices in delis to control growth, cross-contamination, and potential sources of
L.
monocytogenes
in addition to continued sanitation will prevent illness from foods
handled at retail (USDA-FSIS and FDA
2013
).
Retail delis have very different operating conditions and expectations than a typi-
cal RTE food production/manufacturing facility.
L. monocytogenes
may enter the
deli on customers' and workers' shoes, cart wheels, raw meats, fresh produce, and
RTE meats handled in the store. Studies conducted in the US in 2009-2011 found
that 55-65 % of retail delicatessen establishments have
L. monocytogenes
on food
contact and nonfood contact surfaces (Sauders et al.
2009
; Hoelzer et al.
2011b
;
Simmons et al. unpublished
). In some deli departments, contamination may be
found on almost 40 % of all surfaces tested (
Simmons et al. unpublished
). Deli
meats, salads, and cheeses may be sliced, repacked, or portioned for customers in
retail stores. All of these processes expose the food to the environment, food han-
dlers, and equipment, any of which may carry or transfer bacterial cells to the food
if sanitation and hygiene procedures are not properly carried out.
5.3.2
Nonfood Contact Surfaces Are More Likely
to Be Contaminated
The likelihood of
L. monocytogenes
contamination varies based on the type of sur-
face (Table
5.1
). Nonfood contact surfaces (NFCS) (e.g., fl oors, drains, walls) har-
bored
L. monocytogenes
on 15-20 % of samples, while only 2-4 % of food contact
surfaces (FCS) (e.g., slicer blades, utensils, cutting boards, countertops) were con-
taminated (Sauders et al.
2009
; Hoelzer et al.
2011b
;
Simmons et al. unpublished
).
NFCS are more likely to be contaminated due to (1) the foot traffi c which may
introduce and spread the bacteria; (2) many are soil collecting points from the entire
environment (e.g. drains); and (3) infrequent cleaning may allow pathogen growth.
Irrespective of the surface type, ineffective cleaning and sanitation can allow
L. monocytogenes
to grow and persist, potentially remaining for months or years in
the deli environment (
Simmons et al. unpublished
).
5.3.3
Transient v. Persistent
L. monocytogenes
Contamination: the Difference Between Short-
and Long-Term Challenges
In delis with
L. monocytogenes
contamination, distinguishing between transient
and persistent contamination patterns determines which actions are needed to
eliminate the organism. Transient organisms, those that can be introduced and
