1. First, create a clean break on the
packing line, from the beginning to
the end of where the edible product is
exposed to the environment. If you’re
confident that all food contact surfaces
are sanitized, your normal cleaning/
sanitation should be adequate.
2. Run all moving parts for an
hour. This is important to squeeze and
shake out hidden microorganisms that
are not exposed to normal sanitation
procedures. Only run product if needed
for the equipment to run.
3. Stop the line and swab as many
food contact surfaces as possible. Because this is done only periodically
and not weekly or monthly, this is the
time to be aggressive. Many companies
report that when regulators do a “
swa-bathon,” they take hundreds of samples.
You should too! Send all swabs for
Listeria spp. testing.
4. If product was run, reclean and
resanitize per normal procedures. If no
product was run, just resanitizing may
be enough. This creates a clean break
at the other end of your environmental
testing. If product was run, hold until
results are known or discard.
5. If you can afford to hold the
line down until results are known, do
so. Otherwise, resume production.
6. If results are all negative, you have
evidence that the line did not have an
entrenchment, with confidence propor-
tional to the degree of swabbing per-
formed. You will want to keep a record
of what was done and when, and the
7. If any results are positive, you
have evidence of a possible entrenchment. Even though the approach cannot determine whether the Listeria was
pathogenic, it’s critical to react as if it
were Lm: Shut down the line and investigate until the entrenchment is found
and destroyed. This will probably
require more than just resanitizing. A
good investigation will identify possible
factors leading to the harborage and
determine steps to prevent a recurrence.
8. Because 1) the contamination
originated with you, 2) you discovered it
and 3) no product was distributed into
the marketplace, there is no requirement
to file a report in the Reportable Food
There is a new twist in the world of
liability, and that relates to WGS. FDA,
FSIS and the U.S. Centers for Disease
Control and Prevention have made it
clear that WGS is the technology of the
future when it comes to outbreak investigations. Rather than simply evaluating
the number of positive Lm swabs an
investigator finds, these agencies will be
determining whether there is a resident
strain or two that appear in numerous
locations and/or during multiple inspections over time.
Several companies have asked
whether they should begin using WGS
to better understand their production
environment. I feel that WGS could
provide insight into an investigation—
but only after all other approaches have
been exhausted. As noted above, a
positive for Listeria spp. needs immediate attention. The decision to speciate
would come later in an investigation.
Using WGS takes it a step even further.
Industry should ask regulators whether a
proactive company-led investigation using WGS will be used by the agency to
support a judgment of “insanitary conditions,” or whether it will be viewed
in a positive light, demonstrating an
aggressive and protective approach to
food safety. About 20 trade associations
representing the food and beverage industries, and spanning FDA- and FSIS-regulated products, have recently begun
discussing these and other issues so that
we can provide our members with the
best advice on how to view environmental monitoring for pathogens in
light of WGS.
No one wants their product to cause
foodborne illness. Historically, the food
associated with a case of foodborne illness was rarely discovered. WGS will
change that, and I predict that we’ll see
many more instances where regulators
are able to link illness with an environmental test result. Now more than
ever, it’s critical that facilities undergo
a thorough evaluation of their environment. Ignorance is not bliss, because in
this day and age, if your facility is host
to resident pathogens, they will be discovered. For the sake of your consumers
and your reputation, it’s better that you
take control of the situation yourself. n
Jennifer McEntire, Ph.D., is vice president of food
safety & technology at the United Fresh Produce
Environmental Monitoring Resources
• Innovation Center for U.S. Dairy. 2015. Control of Listeria monocytogenes.
Guidance Document for the Dairy Industry. www.gmaonline.org/file-manager/About/Guidance_for_the_us_dairy_industry_ 10_ 19_ 15.pdf.
• GMA. 2009. Control of Salmonella in Low-Moisture Foods. www.gmaonline.
• National Pasta Association. 2015. Mitigation and Control of Salmonella in
Dry Pasta. www.gmaonline.org/forms/store/ProductFormPublic/mitigation-of-salmonella-dry-pasta.
• United Fresh Produce Association. 2013. Guidance on Environmental
Monitoring and Control of Listeria monocytogenes for the Fresh Produce
Additionally, the Produce Marketing Association maintains a list of resources
related to Listeria: www.pma.com/content/articles/2016/05/listeria-resources.