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Cleaning and sanitizing are essential to preventing the
spread of bacteria. Listeria monocytogenes can survive on
various surfaces, including stainless steel, which is a common food contact and non-food contact surface in retail deli
operations a (e.g., slicers, working tables, and carts). Listeria
monocytogenes has an ability to persist in biofilms; it is this
biofilm that protects the microorganisms (9). Microorganisms that have biofilms are hard to destroy because of their
resistance to sanitizers (32). Sanitizer resistance (sanitizer
tolerance) is an important survival strategy of these pathogenic microorganisms (e.g., Listeria) (1, 27, 41). Retail
delis generally used quaternary ammonium compounds as
sanitizers (43). However, the effectiveness of these sanitizers
to eliminate pathogens, such as L. monocytogenes, could be
reduced with the presence of organic residue due to improper
cleaning or biofilm formation of the microorganism (32).
Therefore, it is important to reinforce proper cleaning and
sanitizing to prevent the growth of L. monocytogenes within
retail deli establishments. With the ability of Listeria to exist
in biofilms, it is recommended that the sanitizers used in
the retail deli operations be rotated over time, as noted in
the USDA FSIS best practices guidance, "rotate sanitizers as
needed to provide more effective bacterial control" (46).
This study compared adherence to the USDA eight
recommendations between selected participating retail delis
in Iowa with federal data specifically for Iowa (17). When
assessing compliance solely related to overall compliance with
all eight recommendations, findings were different. On the
basis of federal data results (17), there were 58 (38%) retail
delis in Iowa adhering to all eight recommendations; however,
for the current study, only 12 (21.1%) retail delis in Iowa were
found adhering to all eight recommendations. As compared
with the national federal data, the assessed Iowa delis had
lower compliance with seven of the eight recommendations
except the recommendation to cover, wrap, or otherwise
protect all opened RTE foods. Although we did not directly
study the relationship, one possible explanation for a lower
compliance rate may be in the rigor of the methods used for
this study. Inspectors received intense training and "mark-up"
instructions to make certain that their evaluations were as
accurate as possible when completing the assessment. Thus,
the Iowa dataset may be more reliable because confirmation of
observations was done. In addition, when observation was not
possible (e.g., the observer was not in the facility for 4 h), deli
managers and/or employees were questioned.
With regard to the USDA FSIS eight recommendations,
large retail deli operations in Iowa had a higher percentage as
compared with small deli operations in Iowa. This finding is
similar with previous studies that found both chain and larger
establishments' food safety practices had better compliance
than those of independent and smaller establishments.
Researchers have noted that chain establishments may
be more likely to have tested and verified operational
procedures, and they may have better resources, equipment,

and staffing (3-5). Overall comparison of Iowa delis located
in rural areas as compared with more urban areas revealed
those in rural areas had lower compliance with four of the
eight recommended practices. Further study of differences
between locations of deli may be warranted, although size
and location may be linked. More investigation is needed to
determine the main causes of these differences in safe food
handling practices in Iowa. Additionally, given the limitation
of sample size and unequal distribution by location and size,
further statistical analysis was not done. Therefore, future
studies with larger samples could substantiate the trends
presented in this study.
This study assessed the presence of Listeria monocytogenes in zones 1 and 2 during hours when delis were open
for business. Although the presence of L. monocytogenes in
zones 1 and 2 in sampled Iowa retail delis was relatively low,
additional sampling in zone 3 may have revealed different
findings, as was observed in the corrective action sampling.
Because zones 3 and 4 may not be cleaned and sanitized to
the same degree as zones 1 and 2, incorporating these zones
into sampling procedures for future studies is needed.
Overall, adherence to all best practice guidance was followed by few of the sampled delis, and compliance in Iowa
appeared to be lower than that for the nation. However, over
half of the Iowa facilities adhered to six or more of the eight
recommended practices, which could have been the reason
for the low prevalence of L. monocytogenes. Further studies
are needed to confirm this observation. Environmental monitoring similar to what is required for RTE food processing establishments may be one strategy for continual enforcement,
awareness, and detection of L. monocytogenes in the retail deli
environment (47). The FDA recommends that food processors introduce an environmental monitoring program into
their operations. Food processors have several other control
measures to consider when trying to mitigate the presence of
Listeria in their facilities. These control measures, as well as
implementing an environmental monitoring program, may
be useful to retail deli operators. The FDA guidance provides
processors different strategies for environmental monitoring
along with sampling considerations and suggestions on written procedures. The guidance also outlines corrective actions
that may be taken in the case of positive L. monocytogenes
detection. Although the guide is focused on processors, retail
delis could gain valuable insight and procedures to control
L. monocytogenes in their establishments.
ACKNOWLEDGMENTS
This work was partially supported by cooperative
agreement 5U18FD005612-03 (rapid response teams) from
the U.S. Food and Drug Administration (FDA). Its contents
are solely the responsibility of the authors and do not
necessarily represent the official views of the FDA.

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