Guidance for the Control of Listeria monocytogenes in Ready

Guidance for the Control of Listeria monocytogenes in Ready
Guidance Document
Guidance for the Control of
Listeria monocytogenes in
Ready-to-eat Foods Part 4:
Corrective Actions
13 February 2017
A guidance document issued by the Ministry for Primary Industries
Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
13 February 2017
Title
Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4:
Corrective Actions
About this document
The Ministry for Primary Industries (MPI) has developed a series of documents “Guidance for the control of
Listeria monocytogenes in ready-to-eat foods” that address different areas of L. monocytogenes management
in a food manufacturing or processing environment.
These guidelines are intended to assist food operators to develop, implement and review control measures for
Listeria monocytogenes in the context of a Risk Management Programme (RMP) or Food Control Plan (FCP).
The guidance document are intended to support but do not replace any specific requirements for L.
monocytogenes and/or other pathogen management as described in New Zealand legislation, such as the
Animal Products Act 1999, for dairy and seafood, or under the Food Act 2014.
Related Requirements
The documents in the series Guidance for the control of Listeria monocytogenes in ready-to-eat foods are:
(1)
Part 1: Listeria Management and Glossary; and
(2)
Part 2: Good Operating Practices (GOPs); and
(3)
Part 3: Monitoring Activities; and
(4)
Part 4: Corrective Actions.
Document history
Previous
Version Date
Current
Version Date
December 2012 February 2017
Ministry for Primary Industries
Section Changed
Change(s) Description
Entire document
 Split Part 3: Microbiological testing
for verification of the control of
Listeria monocytogenes into two
documents;
 New format and branding;
 New section numbering;
 Updated text for improved clarity;
 No technical content change.
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
13 February 2017
Contact Details
Judy Barker
Manager, Animal Products
Ministry for Primary Industries
Contact for further information:
Ministry for Primary Industries (MPI)
Regulation & Assurance Branch
Animal and Animal Products Directorate
PO Box 2526
Wellington 6140
Email: [email protected]
Disclaimer
This guidance does not constitute, and should not be regarded as, legal advice. While every effort has been
made to ensure the information in this guidance is accurate, the Ministry for Primary Industries does not accept
any responsibility or liability whatsoever for any error of fact, omission, interpretation or opinion that may be
present, however it may have occurred.
Copyright
Crown copyright ©. This copyright work is licensed under the Creative Commons Attribution 3.0 New Zealand
licence. In essence, you are free to copy, distribute and adapt the work, as long as you attribute the work to the Ministry for Primary
Industries and abide by the other licence terms. To view a copy of this licence, visit http://creativecommons.org/licenses/by/3.0/nz/.
Please note that no governmental emblem, logo or Coat of Arms may be used in any way which infringes any provision of the Flags,
Emblems, and Names Protection Act 1981 or would infringe such provision if the relevant use occurred within New Zealand.
Attribution to the Ministry for Primary Industries should be in written form and not by reproduction of any such emblem, logo or Coat of
Arms.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
13 February 2017
Contents
Page
1
Purpose
4
2
Background
2.1 What is covered by this Part?
2.2 How does this Part relate to the other parts of the guidance for the control of Listeria
monocytogenes in ready-to-eat foods
4
4
3
Definitions
5
4
Notification that Listeria has been detected
4.1 Where can notifications come from?
4.2 Notification of a ‘presumptive positive’ test result
4.3 Confirmation that Listeria is present
4.4 Initial actions
5
5
5
5
6
5
Responding to a Listeria detection in Zones 1-3
5.1 Outside the processing area - Zone 1
5.2 Standard hygiene area - Zone 2
5.3 Critical hygiene/high care area - Zone 3 (non-product contact surface)
5.4 Finding Listeria spp. when processing RTE product intended for consumption by
vulnerable populations
7
7
7
8
4
9
6
L. monocytogenes is found in Zone 4 (product contact surface) or product
6.1 Detection on product contact surface
6.2 Detection of L. monocytogenes in RTE product
6.3 Control product
6.4 Find the source of the contamination
6.5 Sampling and testing of product on hold
11
11
11
14
16
20
7
Resuming processing of RTE foods
7.1 Managing product once processing resumes
23
23
8
Disposition of contaminated or potentially contaminated product
27
9
Prevention of future contamination
9.1 Actions to prevent reoccurrence
9.2 Review of L. monocytogenes management controls after the event
9.3 Documentation, records and reporting
28
28
28
29
Appendix 1: Sample taking and testing during a contamination event
30
Appendix 2: Sample selection for testing product
31
Appendix 3: Product Disposition Form
32
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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1
Purpose
The documents “Guidance for the control of Listeria monocytogenes in ready-to-eat foods” have been
developed by the Ministry for Primary Industries (MPI). This guidance document is Part 4 in the series of
guidance documents and provides information on how to act in response to the detection of Listeria
monocytogenes in the processing area or in ready-to-eat products. This guidance document should be used
in conjunction with the other documents in the series to provide an overall strategy for managing Listeria
monocytogenes in a ready-to-eat (RTE) food operation.
2
Background
2.1 What is covered by this Part?
Part 4 describes how to act in the event that Listeria is found in a RTE food or in the processing area. The
responses include both corrective and preventative actions.
This guidance may provide some useful information for food operators:



developing new operations and/or product lines or ranges;
reviewing existing policies and procedures for the control of Listeria; and
for other food operators who may have Listeria control measures described elsewhere, e.g. dairy and
seafood industries.
The key source of listeriosis cases is the consumption of foods contaminated with L. monocytogenes. In
particular those that are ready-to-eat, support the growth of Listeria, are stored under refrigeration
temperatures and have a long shelf life.
All Listeria species can be found in the same niches in a processing environment. Finding any Listeria
identifies the need to implement or increase control measures. Therefore in this document the term ‘Listeria’ is
used to include all Listeria spp. except where the actions relate specifically to the major pathogenic species
Listeria monocytogenes, in particular where it is found in a RTE food or on a product contact surface.
2.2 How does this Part relate to the other parts of the guidance for
the control of Listeria monocytogenes in ready-to-eat foods
Part 1 provides a glossary of terms and information on the characteristics of Listeria monocytogenes, the
sources, the consequences of food contamination and how it may enter the processing environment. It also
provides information on a Listeria Management Programme (LMP).
Part 2 provides information on specific Good Operating Practices (GOP) that should assist in either preventing
contamination of food with L. monocytogenes or managing the pathogen if present.
Part 3 provides information on monitoring activities for verification of the control of Listeria monocytogenes
through microbiological testing.
Part 4 identifies how to act response to the detection of Listeria in the processing environment, ingredients,
raw materials or product.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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3
Definitions
Definitions used in this guidance document can be found in Part 1: Listeria Management and Glossary.
4
Notification that Listeria has been detected
The LMP should include a response plan that identities the actions that should be taken when notified that
Listeria has been detected. Ideally the plan should have been tested and reviewed using a mock notification
and response involving all relevant staff.
4.1 Where can notifications come from?
An operator may be notified that Listeria monocytogenes has been detected in a food, ingredient or raw
material or in a sample from the processing environment by:





a regulator conducting a survey, or
a regulator following investigation of a food complaint, illness or other event, or
a supplier of raw materials or ingredients, or
the laboratory in response to the operator’s own testing programme, or
a customer.
Note: The detection of Listeria from the processing area is more likely to be reported as part of the operator’s
environmental testing programme.
When the notification is received it is important to have the full details of the sample tested e.g.:



type of sample; and
batch number; and
what the laboratory has found.
4.2 Notification of a ‘presumptive positive’ test result
When the laboratory notifies a ‘presumptive positive’ test result, this indicates that there may be Listeria
contamination of product (or a product contact surface). The laboratory will need several days to provide a
confirmed test result. Most presumptive results will be confirmed to be Listeria. Whether it is Listeria
monocytogenes or another Listeria spp. will usually not be evident until the confirmed result is available.
Refer to Part 3: Monitoring Activities, for more detail about working with a laboratory and understanding the
results in the laboratory report.
Operators should begin to respond as soon as they receive notification of a presumptive result. Taking
corrective action early has the potential to limit the financial cost and effort required in undertaking corrective
actions, especially when product is involved.
4.3 Confirmation that Listeria is present
The scale of the response should be proportional to the likelihood that the RTE food could be contaminated
with Listeria. The likelihood of Listeria being found in the product is low if the positive sample has come from
the external areas (Zone 1) or the standard hygiene areas (Zone 2). The likelihood increases if Listeria was
found in Zones 3 or 4 (high care area/critical hygiene area). See Part 3 for a description of Zones.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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4.4 Initial actions
All responses and actions made to finding Listeria should be based on robust and adequate information. Once
the relevant information has been gathered, the appropriate response can be made. Table 1 includes
examples of the type of information and response required depending on where Listeria was found.
Table 1: Information required to respond to the detection of Listeria
Where was Listeria found? Information needed to help the
response
 The date on which the food was
RTE product sample*
produced, how much, where it is now
 What else was produced about the
same time and might also need to be
included in an investigation
Product contact surface or a
site that could act as a source
of contamination for exposed
RTE product (high care area /
Zone 4)
Non-product contact site in
the high care area / Zone 3
environmental sample site
Zones 1 and 2 environmental
sample sites
Where to find “how to
respond”
Listeria spp.in foods intended for
vulnerable consumers – section
5.4
L. monocytogenes in RTE foods
- section 6
 Listeria species (not L.
monocytogenes) – section
5.4
 L. monocytogenes – section
6
 If a single site sample
(recommended), when was the site
tested previously? What were the
results?
 What foods have been produced
since that test which would have
been in contact with this surface?
 Where is that food now?
Zone 3 – section 5.3
 If a single site sample, what is the
site?
 Was this a composited sample, if yes
what were the sites sampled?
 Are there any issues about the site to
be aware of e.g. equipment that has
been recently serviced or repaired?
 Previous results?
 Was this a composited sample, if yes  Zone 1 – section 5.1
what were the sites sampled?
 When was the site(s) tested
 Zone 2 – section 5.2
previously? What were the results?
* Also includes when Listeria detected in products through customer testing programmes, regulatory surveys
or as a result of illness investigations.
Ministry for Primary Industries
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5
Responding to a Listeria detection in Zones 1-3
5.1 Outside the processing area - Zone 1
The purpose of testing the environment outside the processing area(s) is to:


determine possible sources of contamination so that they can be managed; and
prevent the movement of Listeria into the processing area.
Note: Not all environmental testing programmes will include the sampling of Zone 1 (refer to Part 3).
Suggested actions to take in response to the detection of Listeria in the Zone 1 environment are provided in
Table 2.
Table 2: Suggested actions to take in response to the detection of Listeria in Zone 1
Sampling
Review of results and trend
Listeria controls review and
analysis
corrective actions
 If composite samples were
 Review the trend analysis to
 Review the state of
analysed, take additional
determine patterns of
environmental cleanliness
individual samples to pinpoint
contamination and potential
outside the premises e.g.:
the source of the Listeria.
sources.
 measures to improve
 Repeat sampling after
pest management such
corrective actions taken to
as a bird scarer;
assess effectiveness.
 remove rubbish;
 prevent puddles and
water pooling;
 establish concrete areas
directly outside doors.
 Check that the control
measures for raw materials
and ingredients, equipment
and people that enter and
leave the premises are
operating correctly
5.2 Standard hygiene area - Zone 2
Note: If the operation separates the processing of raw and RTE products using separation by time, unless
there are control measures such as a full clean down between handling raw or RTE products, the entire
processing area should be considered as high care, i.e. Zone 3.
The purpose of testing Zone 2 is to see if Listeria is coming into the processing area. Table 3 provides
suggested actions that can be taken in response to the detection of Listeria in the Zone 2 environment
(standard hygiene area).
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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Table 3: Suggested actions to take in response to the detection of Listeria in Zone 2 (Standard
Hygiene Area)
Sampling
Review of results and trend
Listeria controls review and
analysis
corrective actions
 If the samples were analysed
 Conduct/review the trend
 Isolate and inspect the
as a composite sample, take
analysis to determine patterns
contaminated area and
and analyse individual
of contamination and potential
equipment.
samples from the same areas
sources.
 Review the cleaning and
and surrounding areas to
 Review results from Zone 3.
sanitation programme.
determine the source of the
Reassess access/entry
contamination.
Note: If L. monocytogenes
restrictions into the standard
 Repeat sampling after
continues to be detected in Zone
hygiene area.
corrective actions taken
2 it suggests persistent
 Review the results (if
contamination which will require
 Consider taking additional
available) from outside the
samples to determine whether an increased level of vigilance.
processing environment to
That is, if 3 consecutive sampling
the barriers between the
identify any areas that may
standard and high care areas days of non-detections for L.
require a reassessment of
monocytogenes cannot be
have been breached.
controls to prevent the entry of
achieved, or where the routine
any contamination.
(e.g. 6-weekly) records review
 Take corrective actions as
suggests that there is recurring
appropriate to remove the
contamination.
contamination source and to
prevent reoccurrence in future.
5.3 Critical hygiene/high care area - Zone 3 (non-product contact
surface)
Note: For dairy products processed under a dairy RMP, Zone 3 sites may be considered in the same way as
a Zone 4 sites.
Immediate: Inform the designated person responsible for Listeria management.
The detection of Listeria in this zone could potentially make its way on to product contact surfaces (Zone 4)
and then onto the RTE product. Table 4 provides examples of actions that can be taken in response to the
detection of Listeria in Zone 3 (critical hygiene area/high care area – non-product contact surfaces).
Table 4: Suggested actions to take in response to the detection of Listeria in Zone 3
Suggested actions to take in
Review of results and trend
Listeria controls review and
analysis
corrective actions
response to the detection of
Listeria in Zone 3
 If the samples were analysed
 Conduct/review the trend
 Isolate and inspect the
as a single composite sample
analysis to determine patterns
contaminated area and
(not recommended), take and
of contamination and potential
equipment.
analyse individual samples
sources.
 Reassess processing and
from the same areas and
 Review the testing results
product handling procedures.
surrounding areas to
from the standard hygiene
 Carry out an aggressive
determine the source of the
area (Zone 2).
cleaning and sanitising
contamination.
 Consider taking additional
operation.
 Commence investigative
samples from this area to
 Take corrective actions as
sampling e.g. sampling daily
determine whether the
appropriate to remove the
with a focus on finding and
barriers between the standard
contamination source and to
eliminating the source of the
contamination.
Ministry for Primary Industries
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 After increased cleaning
resample clean areas before
processing recommences.
 Maintain intensified sampling
during processing until at least
3 consecutive sample days
are clear for Listeria.
hygiene and high care areas
have been breached
prevent reoccurrence in
future.
 If corrective actions have not
completely removed the
source of the contamination
and Listeria continues to be
detected, food operators
should be able to demonstrate
that they are taking all
reasonable steps to control
the Listeria contamination and
prevent the contamination of
the high care area.
5.4 Finding Listeria spp. when processing RTE product intended for
consumption by vulnerable populations
If a Zone 4 sample is positive for Listeria species but not positive for L. monocytogenes, this indicates that the
control measures including GOP may not be effective.
Operators should consider taking appropriate actions in response to the detection of Listeria spp. in RTE
products. Often more than one species of Listeria may be present in a food or a niche in the processing
environment but only one is detected in the laboratory or in a particular food sample. Producers of RTE food
for vulnerable consumers should be aware that high levels of L. ivanovii or L. innocua may be a potential
cause of illness in vulnerable consumers.
Immediate action: Inform the designated person responsible for Listeria management.
Table 5 provides examples of actions that can be taken in response to the detection of Listeria spp. in Zone 4
(product contact surface) or RTE products that are intended for consumption by vulnerable populations.
Table 5: Suggested actions to take in response to the detection of Listeria spp. in Zone 4 or RTE
products intended for consumption by vulnerable populations
Sampling
Review of results and trend
Listeria controls review and
analysis
corrective actions
 Increase the testing frequency  Review the trend analysis to
 Clean and sanitise and
for the environment, all
determine any patterns and
sample to evaluate
hygiene areas and product.
potential sources of
effectiveness
contamination.
 Resample Zone 3 (non Review process records to
product contact) and 4
identify whether anything has
(product contact) sites.
changed and to ensure that
the process controls for L.
 Maintain increased daily
monocytogenes are operating
sampling until at least 3
correctly.
consecutive processing days
with clear results are
 Review cross-contamination
achieved.
potential and personnel
movement and access.
 Review product sampling
especially if producing foods
 Prevent potential future
for vulnerable consumers.
contamination from L.
monocytogenes by reviewing
and amending controls where
necessary e.g. personnel
training.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
13 February 2017
Sampling
Ministry for Primary Industries
Review of results and trend
analysis
Listeria controls review and
corrective actions
 Review the cleaning and
sanitation that occurred prior
to and at the time of the
incident.
 Investigate potential sources
of the Listeria contamination
e.g. entry points to the high
care area from the standard
hygiene and external areas,
areas where there are suitable
wet growth conditions and
transfer mechanisms.
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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6
L. monocytogenes is found in Zone 4 (product contact
surface) or product
6.1 Detection on product contact surface
If L. monocytogenes is found in a Zone 4 site, product may also be contaminated. The response should be the
same as when Listeria is found in product to ensure that no RTE product has been contaminated (refer to
section 6.2 and figure 1).
Immediate action: Inform the designated person responsible for Listeria management.
6.2 Detection of L. monocytogenes in RTE product
This section describes recommended actions in response to:


the detection of L. monocytogenes in RTE product; or
when L. monocytogenes is found in Zone 4 (product contact surfaces which come into contact with
exposed product prior to packaging).
The contamination could have resulted from either contact with a contaminated surface or faulty processing.
In the latter case, the contaminated process could then contaminate product contact surfaces. It is
recommended that the recommended actions in Figure 1 are taken in addition to the initial actions listed in
section 4.4.
If the food has received a listericidal process the presence of Listeria indicates that there has been a failure of
process control or hygiene that has resulted in post-processing contamination. Operators should make an
immediate response irrespective of the applicable microbiological limit for L. monocytogenes in the Food
Standards Code 1.6.1 – Schedule 27.
Immediate action: Inform the designated person responsible for Listeria management.
See Part 1 for information on identifying the microbiological limits that apply or are appropriate for a RTE
product.
Refer to Table 6 for suggested actions to take in response to the detection of L. monocytogenes in product but
at levels permitted in Standard 1.6.1.
Refer to Figure 1 for a breakdown of the recommended actions when Listeria is detected in product. This
figure summarises the actions detailed in sections 6, 7, 9 and 10.
Recommended actions when L. monocytogenes is found in product but at levels permitted in
Standard 1.6.1
If counts up to 100cfu/g are permitted but the food has received a listericidal process, the presence of Listeria
indicates a failure of process control or that post-processing contamination has occurred. Operators should
consider an immediate response as for products where there is an ‘absent in 25g’ limit.
The product should be either:


withdrawn from sale; or
placed on hold until the extent of contamination is known and appropriate disposition is agreed.
Ministry for Primary Industries
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If counts up to 100cfu/g are permitted but the food is minimally processed e.g. salads, non-shelf stable pesto,
processed fin-fish, low levels of Listeria may sometimes be present. Corrective actions should be taken, the
range of actions may depend on the level of L. monocytogenes detected and whether the operator has
validated that only limited if any growth will occur during the products shelf life (i.e. will not exceed 100cfu/g at
the end of its shelf life).
Table 6: Suggested actions to take in response to the detection of L. monocytogenes in product but at
levels permitted in Standard 1.6.1
Sampling
Review of results and
trend analysis
Listeria controls review and corrective
actions
 Increase the frequency and numbers
of product samples taken during
future production in a long shelf life
product, especially if contamination
has not been found previously.
 Collect product samples from all
product batches made since the
product batch in which Listeria was
found. This will help to determine if
Listeria is present in other batches.
 Review environmental
sampling results for
possible contamination
sources.
 Review the processing and incoming
raw material to see if any changes or
one off events could have contributed to
Listeria being present e.g. damaged
produce, heavy soil load depleting
sanitiser activity.
 Review processing, cleaning and
sanitation and/or suppliers if occurrence
becomes too frequent or counts near
the permitted limits.
Ministry for Primary Industries
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Notification of L. monocytogenes detection received
Initial response - Control
product (see 6.3)
 Stop processing if
practical (see 6.3.1)
 Isolate contaminated
areas and/or
equipment (see
6.3.2)
 Notify regulator (if
required) (see 6.3.3)
 Identify and hold
contaminated and
potentially
contaminated
product(s) (see
6.3.4)
 Withdraw or hold
contaminated and
potentially
contaminated
product (see 6.3.5)
Find the source of the
contamination (see
6.4)
 Look for possible sources and
transmission routes (see 6.4.1)
 Review supporting systems and
processing records and process
inputs (see 6.4.2 – 6.4.4)
 Inspect process areas and
equipment (see 6.4.5)
 Thoroughly clean and sanitise
affected area; take before and
after samples (see 6.4.6)
 Within 1 working day undertake
investigative environmental
sampling of product contact
surfaces and other sites within
the critical/high care area
 Continue sampling at high rate
until the source of the
contamination has been
identified (see 6.4.7)
Identify contaminated batches of
product and the extent of the
contamination (see 6.5)
Resuming processing (see 7)
 Sample as much potentially
contaminated product as is
available, including any
product received as a result of
withdrawal or recall (see 6.5.2
and Figure 2)
 Sample each batch of
potentially contaminated
product according to Table 8
(see 6.5.3)
 Any batch that detects L.
monocytogenes is to be
handled in accordance with
section 8
 Release of product to be
assessed on case by case
basis
 Product and product contact
surface sampling after
processing resumes (see
7.1) according to Table 9.
 If there are any detections
of Listeria, all available
product should be tested at
the recommended level.
(Table 9)
 Any batch that detects L.
monocytogenes to be
handled in accordance with
section 8
Take appropriate
corrective actions to
prevent recontamination
(see 9)
 Clean and sanitise
 Deal with affected
product
 Escalate response if
detections continue
 Review the
management controls
after the event (see
9.2)
 Ensure that
documentation is
complete (see 9.3)
Figure 1: Actions to be taken when L. monocytogenes is detected in product
Ministry for Primary Industries
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6.3 Control product
6.3.1 Stop processing
For some processes (e.g. continuous operations) it may not be possible to stop processing. If processing
continues, all resulting product from the affected lines should be considered as potentially contaminated.
Product contaminated because of inadequate process control may act as a source of contamination for
subsequent production, either by direct contact with other product or indirectly by contaminating product
contact surfaces.
6.3.2 Isolate contaminated equipment and area(s)
If processing has been halted then isolate the following areas:



the processing areas (including equipment) that have processed contaminated product after a
listericidal step; or
all processing areas that have processed contaminated product where there is no listericidal step; or
high care areas from which a product contact surface has tested positive for L. monocytogenes.
All high care areas may be contaminated. It is possible that standard hygiene areas contain the source
and that routine testing has not been effective at identifying that source.
Consider restricting access to and from these areas to essential staff members only. Access can be restricted
by:



keeping the door shut into a separate room; or
taping off areas; or
using personnel control (e.g. foot baths, clothing exchange, appropriate signage etc.).
6.3.3 Notify the regulatory authority (where appropriate)
Dairy and seafood operators under the Animals Product Act 1999 (APA), are required to notify their verifier
within 24 hours of receiving confirmation of the detection of L. monocytogenes in product or, depending upon
the programme, on product contact surfaces1.
All other food operators under the APA and the Food Act regime are expected to notify the relevant regulatory
authority (verifier, Food Compliance Officer or MPI) if affected product has left their control such that a recall
(trade or consumer level) of the product is required.
For dairy operators under the APA the requirement is specified in regulation 5 of the Animal Products (Dairy)
Regulations 2005, section 5 of the Animal Products Notice: Dairy Processing Specifications and section 7 of
DPC 1: Animal Products (Dairy): Approved Criteria for General Dairy Processing. For RTE seafood
processors under the Animal Products Act the requirement is specified in the Animal Products (Risk
Management Programme Specifications) Notice 2008 clause 13(3)(a) and expanded upon in the Processing
of Seafood Code of Practice section 18.9.2.
The management of contamination events for dairy processors under the Animal Products Act will remain with MPI. MPI will continue to make any
disposition rulings for that sector.
1
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6.3.4 Identify and hold contaminated and potentially contaminated product(s)
Potentially contaminated product includes:


product processed on a line where Listeria has been detected on a product contact surface, and/or
on a line used to process product in which Listeria was detected.
Actions include:




isolate the product (where possible) and hold to prevent it being used, sold or distributed, including any
product received as a result of withdrawal or recall;
prevent direct contact or cross-contamination with other product(s), raw materials, packaging,
equipment or surfaces;
clearly identify product to indicate status. For example, each carton or pallet could be marked with
‘hold’ labels, or it could be held using an electronic inventory control system to ensure product is not
released;
prepare a full product inventory. Determine which products, where and how much is affected.
Other products may be contaminated as a result of being processed:



on the same line; or
in the same processing room around the time of a contamination; or
may be subsequently contaminated once processing resumes.
It is important that all resources available are used to help narrow down the range of potentially contaminated
product so that the response and testing can be targeted. This can be achieved by reviewing the results from
routine testing and investigative sampling, as well as reviewing the process control and supporting system
records.
To help visualise what should be considered when determining which product may be contaminated and what
testing may be required, refer to Figure 2.




Figure 2, day zero represents the day that the sample was taken that tested positive for L.
monocytogenes and may be the first evidence of a contamination event. In this example, the result is
notified on day 5.
The days that pass between the last clear test and when the positive sample was taken are
represented by Xs. The number of “X days” will be determined by the frequency at which routine
testing samples are taken. If routine testing samples are tested more frequently, this will be a shorter
timeframe and fewer products may be affected provided a robust testing programme has been used.
Contamination notified on day 5 could have been occurring since the last clear test (or longer). At this
stage, the food operator does not know when the process hygiene failed.
Product processed on days indicated by Xs, if available, should be identified and held so that testing
can be carried out. This will assist in the identification of the onset of the hygiene failure.
The days numbered 1 to 5 represent product that was produced between taking the positive sample
and notification of the detection. Potentially contaminated batches should be held so that testing can
be carried out.
6.3.5 Withdraw or recall contaminated product
If contaminated product has left the processing premises but remains within the company’s control consider
whether it should be withdrawn from the distribution chain. If contaminated product has left the company’s
control it is likely that a recall (trade or consumer level) will be required.
Any contaminated or potentially contaminated product that remains under control of the operator should be
placed on hold.
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
Under section 284 of the Food Act 2014, the Chief Executive may issue an order directing the recall
food or a food related accessory that is not safe or suitable or whose safety or suitability is in doubt.
Under section 85 of the Animal Products Act 1999, the Director-General may issue a notice directing
the recall of any animal product that is not fit for intended purpose or whose fitness is in doubt.

The decision to recall product should take into account:
 whether the product is still within shelf life;
 whether the positive result was in product or on a product contact surface;
 the level of contamination in the product and the risk presented by it;
 the intended consumer;
 where the product is in the distribution chain and/or whether it remains within the company’s
control.
If a recall is required then the regulatory body is likely to require the following information:




details about the contaminated and potentially contaminated product (shelf life, batch number(s) or
other identification); and
current location, distribution and volume of affected product; and
routine testing sampling plans, results and trend analysis of environmental results; and
any decisions about the disposition of the food product.
The MPI Recall Guidance Material provides guidance for the food and beverage industry and sets out the
procedures for identifying and removing unsafe food from the food chain. This can also be found by using the
search terms “recall guidance material” in the search field of the MPI website.
6.4 Find the source of the contamination
6.4.1 Look for possible sources and transmission routes
Finding the source or cause of the Listeria contamination can help to minimise any future reoccurrence by
allowing the food operator to tighten or put in place control measures (refer to Table 7).
Table 7: Actions to help identify possible sources of Listeria contamination
Action
Rationale
Review the access controls for people, raw materials,
The detection of Listeria suggests that one of
equipment, packaging and any other materials and
the control measures (GOP or process controls)
previous testing results upon notification of the
that are in place to prevent pathogen
detection of Listeria.
contamination has not been effective
Systematically review the floor plans and process flows Identifies anything that may be a cause for
through the premises.
concern and that should be targeted during the
investigation.
Assess the integrity of the building.
Possibility of unsealed doors or windows, roof
leaks, unflashed pipes and untrapped drains
causing problems.
6.4.2 Review supporting systems
Reviewing the supporting systems (GOP) helps to identify the cause of the contamination (e.g. cleaning and
sanitation programme, access restrictions, GOP, staff training).
Aim to check any records for the period around the date of detection, and if possible back to the last nondetected result, to identify whether anything unusual or unexpected occurred.
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Checklist for reviewing the support systems
 Were the cleaning and sanitation procedures followed correctly, including chemical concentrations and
contact times?
 Was there an equipment breakdown or maintenance work being carried out on or near the process
line(s)?
 Was there a large order processed or a new product?
 Did any modifications or repairs take place at or near the line(s) such as replacing flooring or repairing
a refrigeration unit?
 Are there ongoing problems that could be linked to the hygienic design of the equipment or facilities?
 Were there new or inexperienced personnel on the process line(s)?
 Were the access/entry restrictions into high care areas being followed correctly, including any
movement of equipment between areas?
 Was there a breach of the hygiene requirements?
 Was there potential for cross-contamination between the high care area, product contact surfaces
and/or product?
6.4.3 Review processing records
Reviewing the processing records helps to establish:


the extent of possible contamination; and
which product lines could potentially be contaminated.
This review should assist in determining whether the process was under control and that procedures were
being followed.
Aim to check the records that date back to the last non-detected result for Listeria species and see if the
process is operating as intended.
Checklist for reviewing the processing records
 Check CCPs specific to the control of Listeria (e.g. heat treatment steps).
 Do records show that the critical limits were being met?
 Was the equipment used for critical measurements calibrated (e.g. thermometers, pH probes, pressure
gauges etc.)?
 Are the readings accurate?
 Where necessary, recalibrate the equipment.
 Check the competency and training of workers responsible for supervising CCPs. Observe them
performing their tasks and assess their competency by questioning the actions that would be taken
given certain scenarios.
 Was there a loss of process control at any particular step?
 Were the processing parameters met (time or temperature of freezer, refrigeration, heat shock, etc.)?
 Were there changes to product formulation, ingredient substitutions or were ingredients from a different
supplier used?
 Review ingredient records and the traceability of those ingredients to the process (refer to section
6.4.4).
 Were the process and handling procedures followed correctly?
 Were there frequent changes to the process line(s)? For example, the speed, stoppages or several
changes to lots of ingredients and materials used.
 How many product lines or product batches are possibly contaminated?
 For example batches produced in common facilities as the contaminated product between major
clean downs, and product produced on previous and subsequent processing days.
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
Section 6.5.2 provides further guidance on how to determine what and the volume of product
affected.
All these activities should be occurring as part of a standard operation. It can be useful to for people who
have not previously been involved to provide a fresh set of eyes.
In practice, it is useful to set up a system that allows the data from checks and testing undertaken to be
visualised and updated, e.g. charts on the event manager’s wall.
6.4.4
Sampling process inputs
Listeria can enter the processing area and into the food product via inputs, ingredients and raw materials,
such as additives, processing aids and packaging materials, etc.
To assist in the identification of the source of the contamination, the inputs used should be reviewed. Test
samples of any available inputs whose microbiological status cannot be confirmed by other means, e.g.
through verified supplier guarantees, etc., to determine if they are a source of contamination. For example,
using appropriate sampling plans, test:



ingredients;
packaging (including inner and outer packaging, pallets and wrapping, etc.);
in-process materials (also known as intermediaries).
Identify and hold ingredients added to the product after a listericidal step, or that are not subject to a
listericidal step should be identified. This will prevent accidental use until it is possible to confirm whether they
are a source of contamination.
Processes with a listericidal step will be designed to eliminate or reduce L. monocytogenes to acceptable
levels in the final product. If L. monocytogenes is detected in the ingredients or raw material and/or inprocess materials it will be important to check the validation records to ensure that the controls are
adequate to reduce the pathogen to acceptable levels. If this is not the case, the process will need to be
revalidated or an alternative supply of raw material sought. The correct implementation of the controls
should also be checked. Where there is no listericidal step, the raw material supply will need to be
reassessed.
See Part 2 for guidance on process controls and the supply of raw materials (Part 2, sections 7 and 8 for
information on Incoming Materials and Identification and Traceability).
6.4.5 Inspect process area(s) and equipment
Review the floor plan and process flow to identify areas that are the most likely sources of contamination.
Carefully inspect the equipment and process area(s) to identify equipment and area(s) that may be the source
and/or harbourage point of L. monocytogenes. Assess the state of equipment used, including the repairs and
maintenance records to determine whether there are any hidden surfaces that may trap food and allow it to
build up.
The inspection is likely to involve dismantling some equipment and may require assistance from maintenance
personnel. Isolation measures around the area and equipment should be maintained to minimise the spread
of any contamination throughout the area. Refer to Part 2 for tips on the maintenance of equipment and
possible sources of contamination and Part 3, Appendix 3: Examples of potential niches.
If Listeria is detected from a product contact surface and a composite sample was originally analysed, or the
result is from a product, then the particular equipment may not be identifiable. If so, review:
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

the equipment together with the environmental testing results, the process records (refer to section
6.4.4); and
the supporting system records (GOP) (refer to section 6.4.3).
6.4.6 Clean and sanitise the affected area and equipment
If the affected area and equipment are known, swab then thoroughly clean and sanitise and resample to
determine whether corrective actions have been successful.
6.4.7 Conduct investigative environmental sampling to find the source of the contamination
Review environmental testing results
Review the environmental testing results for the standard hygiene and high care areas to indicate where to
focus investigative environmental sampling.


Investigative environmental sampling will help to identify the contamination source(s) and rule out
those areas that are not the source of contamination.
Any investigative environmental sampling should commence as soon as possible, ideally within one
working day after receiving the laboratory notification.
Investigate environmental sampling can be a costly and time consuming exercise and requires collecting a
greater number of samples than those collected for routine testing from the processing environment. Apply
a thorough and systematic sampling plan to help identify the source of the contamination (where possible).
It is important that the investigation is thoroughly planned from the start and that sufficient samples are
taken from well considered sample sites. Every effort should be taken to ensure that sampling does not
need to be repeated due to mistakes or gaps in the initial sampling plan. The number of samples to be
taken will depend on the complexity of the process and equipment, but generally the more samples that
are taken from well considered sites, the better the chances of resolving the problem. Sampling may be
targeted where there is clear evidence to support this.
During the investigation sampling immediately after cleaning is useful because any L. monocytogenes
detected is more likely to be at or near the contamination source.
A person with expertise in Listeria management should be involved.
Getting positive results is good as this means that the sampling programme is effective and specific
corrective actions can then be taken.
In the case of a product contact surface positive:


determine the site, date and time from where the positive swab(s) was taken. If the swabs were
analysed as a composite sample, identify which sample sites were included in the composite;
review the environmental testing results from past testing to determine those sites that tested “notdetected” for Listeria species and those sites with the greatest likelihood of being a source of
contamination (see Table 4 in Part 3 for an example of how results may be recorded for easy review).
In the case of the detection of L. monocytogenes in product:




determine the processing line, date and time when the product that tested positive for L.
monocytogenes was processed;
determine the sample date of the last clear test for L. monocytogenes to help establish the time frame
when potentially contaminated product may have been processed;
use any further product results to assist in expanding or reducing the scope of the search;
sample any likely product contact surface site(s) that have tested positive in the past;
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

select other product contact surfaces and other sites in the high care area, particularly in hard to clean
areas;
consider sampling indirect contact surfaces. These are sites that are not in direct contact with the
product but may be an important source of contamination. For example overhead surfaces from which
condensate may drip on to the product or product contact surfaces.
Taking environmental samples
When taking investigative environmental samples:






include items such as waste from the floor or hidden ledges, product scraps, cleaning equipment when
selecting samples;
Do not composite environmental swabs for microbiological analysis. The use of composite samples
may delay identifying the source of contamination. The exception to this would be if all swabs in the
composite come from the same piece of equipment or same surface;
the sampling method may differ during investigative sampling, for example the area swabbed may be
larger in an attempt to reach greater surface areas or nooks within a piece of equipment;
consider including pieces of equipment, etc. that move between the standard hygiene and high care
areas, including the wheels;
during the investigation swabs from the same piece of equipment can be composited for analysis.
Swabs from different pieces of equipment or surfaces should not;
explore all areas of possible contamination and not just on a limited / small part of the process as this
can delay detecting the source and returning to full production. See Part 3, Appendix 3 for photos of
some potential pathogen niche and harbourage sites.
Where appropriate, intensive sampling should continue until the source of the contamination has been
identified. Intensive sampling may not always find the source of contamination;
After sampling thoroughly clean and sanitise the affected areas to ensure that any harbourage sites that may
have been disturbed do not contaminate the processing areas or product.
6.5 Sampling and testing of product on hold
6.5.1 Intensive microbiological sampling requirements
If an operator intends to investigate the possibility of some of the product on hold being released, this product
will need to be tested intensively to determine extent and level of contamination between each batches.
Intensive microbiological sampling differs from routine testing. Routine testing programmes are designed as
an additional 'check' that a food safety control system is working properly over time rather a pass/fail for each
batch of product.
Intensive sampling programmes are undertaken because a problem has been identified and there is an
increased likelihood that product is contaminated. It cannot be assumed that the system is working as
intended and therefore information on individual batches is required. Only a portion of each batch is likely to
be affected because microbial contamination, unlike some other forms of contamination, tends to be unevenly
distributed. As a result, higher sample numbers per batch are required so they can provide information on the
acceptability of an individual batch. Product to be tested is identified in section 6.5.2 using Figure 2.
6.5.2 Identify product to be tested
Each batch of product on hold may need to be sampled. Testing will help to:

determine which product produced prior to, during and after the contamination event is or is not
contaminated; and
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
allow decisions about the release or disposition of product to be made.
The level of testing should be intensive with samples taken at a higher frequency than during routine
microbiological testing.
Potentially contaminated product processed
around the time of a contamination event and
once processing resumes
Last clear
test from
routine
testing
Notification of
L. mono
detection
+ve sample taken
during routine
testing
Processing
halts, full clean
and sanitation
etc
Contamination
X
X
Pressing Days
0
0
1
2
3
4
Potentially contaminated product that
might be available for sampling
5
1
Environmental
investigation
commences (or
sooner if
possible)
2
3
3 clear test
results
received
4
Y
Y
1
2
Return to routine
testing
Potentially contaminated product and
product contact surface sampling
Figure 2: Which product may be contaminated?
6.5.3 Sampling plans
When conducting intensive microbiological sampling, it is recommended that sampling plans that give 95
percent confidence of detection are used.
When undertaking an intensive sampling programme the food operator should note that:

As the number of samples taken decrease, the chance of accepting an unacceptable product batch
increases. The costs involved in sampling and testing need to be weighed against the impact of
making an incorrect decision.

Sampling using a sample size of 60, i.e. n = 60, per batch provides 95% confidence of detecting L.
monocytogenes in at least one product where 5% of the product is contaminated. If the sample size
was reduced to n= 5 the batch would need to be 45% contaminated for a L. monocytogenes
detection.
For product that will not support the growth of Listeria and that has a limit of 100cfu/g, having the
laboratory enumerate the Listeria present should be considered. This result can then be used to assist in
determining product disposition (refer to section 8). When Listeria will be enumerated the product
samples cannot be composited.
Suggested minimum and recommended sample sizes are presented in Table 8. Samples should be selected
from each batch processed on each suspect line. A maximum of 15 product samples may be composited
unless enumeration is required. The whole sample should be analysed and not a subsample of the composite.
An example of how to select samples from product held in store using a random sampling system is given in
Appendix 2 Sampling selection for testing product.
Table 8: Suggested intensive sampling of product processed prior to or at the time of the
contamination event (see Figure 2)
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Original source of positive
result: Product contact
surface
Sample numbers
Potential contamination likelihood for
product
Medium
High
Minimum
n=5
n=5
Recommended
n=30
n=60
Original source of positive
result: Product
Sample numbers
Medium
High
Sample type: product (25g
samples)
Recommended
n=30
n=60
Sample type: product (25g
samples)
Alternative sampling frequency and number of samples analysed can be proposed.
The minimum suggested sample size is n=5 in the event that the original positive sample was taken from a
product contact surface.
A larger sample size would be needed if product is likely to be contaminated or for a greater degree of
assurance is needed. 60 samples could be taken from each batch of potentially contaminated product and
these could be composited into 5 samples of 300g each for testing. This would reduce the likelihood of the
release of contaminated product to trade.
Further detections would provide evidence that action should be taken to locate and where necessary recall
potentially contaminated product that has left the control of the operator.
6.5.4 Release of product
Potentially contaminated product can be released:




after all the results from all the testing has been received; or
on a case-by-case basis; or
to operator if intended for cooking (using a thermal treatment sufficient to eliminate Listeria); or
for another valid disposition method agreed by the verifier.
The particular approach taken to release product depends on:



the particular contamination event; and
the results from additional analysis of different batches or production days; and
the respective product shelf life etc.
Releasing product prior to the receipt of all results would be a commercial risk unless the release of on-hold
product is approved by the regulator. Product with a longer shelf life should be held pending the outcome of all
results. Batches that are clear from a single day of testing should not be released solely on the basis of that
result (i.e. a series of results to build up a picture of the event should be used).
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7
Resuming processing of RTE foods
The processing of RTE foods might cease whilst corrective and preventative actions are occurring. In order to
restart processing:


these actions should be completed in discussion with the verifier; and
there should be evidence that the L. monocytogenes contamination is under control.
Evidence may include microbiological testing results from the processing areas, trial production runs with
associated testing, validated control measures, etc.
Once there is agreement to restart production there should be an intensive sampling programme for the
processing area and the product. This will help to demonstrate that the process controls and other measures
are limiting the presence and contamination with L. monocytogenes.
7.1 Managing product once processing resumes
There may be a break of days to weeks before processing resumes, as corrective actions such as
investigations, cleaning and repairs and maintenance occur.
Once processing resumes, product and product contact surface samples should be taken to allow
determination of whether the corrective actions have been successful and the contamination source has been
identified and addressed. Testing should continue until there are 3 consecutive processing days of clear
results (see section 7.1.1).
7.1.1 Sampling of product and product contact surfaces when processing resumes
When processing resumes it is important to determine that product processed is not contaminated and that
the corrective actions have been effective. Complementary environmental samples from product contact
surfaces should also be collected and tested.
It is recommended that product should be kept on hold until there have been at least 3 consecutive
days of product and product contact surfaces having acceptable results.
(1)
Product samples should be taken during processing, ideally selected based on random times or hourly.
As an alternative, the first and last products of the batch may be sampled and then further samples can
be taken at 3 hour intervals in the intervening period2.
Collecting samples of the first product processed will only provide an indication of the effectiveness
of the cleaning and sanitation procedures and will not show how well the process is operating.
(2)
Product samples should be selected from each batch processed on each suspect line and may be
composited3 by the laboratory unless enumeration is required.
For product with a short shelf life, sampling and testing may need to occur using trial batches rather than sampling from
full scale production.
3 While compositing of product samples is recommended when sampling product produced around the time of the
contamination event it is not recommended for testing once processing resumes as it does not allow assessment of the
frequency of contamination to be made.
2
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(3)
Product contact surface samples should be individually tested by the laboratory until the event is
resolved. Product contact surface samples should include any sites that have tested positive for L.
monocytogenes and might include other suspect areas.
(4)
Product and product contact surface samples should be taken at the same time, as this will make the
task of determining the appropriate response from any positive result easier if samples are connected
by location and time.
(5)
Any product batches that test positive for L. monocytogenes should be handled in accordance with
section 8. Where there are intermittent detections of Listeria, it is recommended that batches of
product that are clear for Listeria not be released for trade. The product may be contaminated but that
the testing regime has not detected it.
Table 9 provides the suggested and the minimum sample numbers for product and product contact surfaces
for each batch processed on each suspect line in relation to product or each processing day for product
contact surfaces.
Table 9: Suggested intensive sampling of product and product contact surfaces once
processing resumes
Original Source of positive
result: product or product
contact surface
Sample type: Product (25g
samples)
Sample type: Product contact
surface
Sample numbers
Potential contamination likelihood for
product
Medium
High
Minimum
n=5
n=5
Recommended
n=30
n=60
Minimum
n=5
n=5
Recommended
n=30
n=60
Alternative sampling frequency and number of samples analysed can be proposed.
7.1.2 If Listeria is detected on product contact surfaces and product once processing
resumes
If Listeria is detected once processing restarts on product contact surfaces or in the product then the operator
should take further corrective actions. Sampling at the increased frequency should occur on all available
product batches produced since the last clear test for L. monocytogenes and on all future batches produced.
This should include any product batches that were cleared using a n=5 sampling plan. This but does not
include product batches that have had a detection for L. monocytogenes, as these should be disposed of in
accordance with section 8.
If there are further detections after processing is resumed, the response should escalate to increase the
likelihood of identifying the source of contamination and to take additional corrective actions.
(1)
As a minimum, a deep clean and sanitation would be expected before processing continues.
(2)
Consider whether structural repairs may be needed required to the processing area, additional repairs
and maintenance and stricter access controls.
(3)
Re-evaluating possible sources of environmental and equipment contamination should occur and,
where appropriate, intensify environmental sampling.
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After further detections of Listeria it is recommended that intensive sampling of product and product contact
surfaces is conducted at n=30 or n=60 sampling numbers rather than at the minimum to ensure that the issue
has been resolved (refer to Table 9).
If Listeria species continues to be detected on product or product contact surfaces after nine days of intensive
testing, seek further assistance to:


identify the contamination source; and
take appropriate corrective actions.
Nine days should allow time to obtain results from 3 consecutive testing days for Listeria species from the
date that notification of L. monocytogenes was initially received, provided testing is well managed and
laboratory facilities are available as required.
7.2 If L. monocytogenes continues to be detected
7.2.1 How to respond
The continued detection of L. monocytogenes in product or on product contact surfaces (i.e. 3 consecutive
days of not-detected results for Listeria cannot be achieved after nine days of sampling) should result in an
escalated response. The continued detection of L. monocytogenes suggests that there is a bigger, more
persistent problem within the premises.
There may be greater involvement from the verifier, Food Compliance Officer and/or MPI in the event of the
ongoing detection of Listeria.
The actions described in the section 6 continue to apply.
Checklist: Suggested actions in the event of further detections of L. monocytogenes
Consider:
 Stopping any processing on the implicated line, contaminated processing area or of the products
producing positive results. This will provide the opportunity to conduct and obtain the results from
additional investigations. Processing should not recommence unless:
 the cause has either been identified and eliminated; or
 an effective post-pack anti-Listeria treatment can be implemented; or
 the product will be sold to a food processor or food service food operator for further processing
using a valid listericidal process.
 Observe food processing, the movement of the food intermediaries and product, equipment and staff
within the premises. Whilst doing this consider:
 whether office staff, maintenance workers and the truck drivers walk through the processing area
on the way to and from office, staff room etc;
 whether external doors and windows are left open;
 whether equipment and the food intermediaries travel back and forth across the processing area,
is there clear separation between the raw and finished RTE product?
 how staff behave around food, do they understand the importance of not crossing a ‘red line’
between raw and RTE product?
 how separation between the raw and RTE product is managed;
 whether there are areas where water pools on the floor
 whether the equipment and premises is visibly clean. Is there a build-up of waste product on
conveyor belts, fans, etc?
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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 Engaging an external expert to review the actions to date and assist in the resolution of the event. A
fresh set of eyes can often spot potential sources of cross-contamination or practices that may result in
the contamination of the food product that those closer to the issue may not see.
 If processing continues in the affected area, all of the resulting product should be considered potentially
contaminated and sampled using the intensive sample plan (section 6.5.3, Table 8).
 Serotyping or DNA fingering printing (PFGE) if this is not already occurring.
 Whether a recall should be expanded to other batches, particularly in relation to long shelf life products.
Any further product received as a result of an expanded recall may be sampled and tested.
 Continued environmental sampling in accordance with section 7.1.1 to identify any contamination
source(s).
 Intensive cleaning and sanitation procedures, including dismantling equipment and deep cleaning.
 Reviewing design and construction issues and addressing any problems.
 An in-depth review of application of HACCP, systems and procedures, wherever possible using people
not previously involved in the event.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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8
Disposition of contaminated or potentially contaminated
product
The disposition of contaminated or potentially contaminated product does not always mean the product should
be destroyed. In some cases, the product may undergo alternative disposal or decontamination options such
as reprocessing or use in non-food applications.
If product is reprocessed then this should be done using a process that has been validated as capable of
destroying L. monocytogenes. There should be documented evidence of the process validation. If
contaminated or potentially contaminated product is to be reprocessed, the documents accompanying the
product should clearly indicate the requirement for a listericidal treatment. The further processor should have
documented evidence that the process will eliminate L. monocytogenes.
If reprocessing of exposed product is to take place on the same process line where L. monocytogenes was
detected, then this should not occur until results indicate that L. monocytogenes is not detected on product
contact surfaces on 3 consecutive processing days. Otherwise, all reprocessed product will need to be
retained and tested at the intensive sample size (see Table 9).
When determining product disposition options consider:










the quantity, identification and labelling information of the contaminated product(s);
the microbiological limits for L. monocytogenes that apply to the product;
the level of L. monocytogenes in the contaminated product(s), if known;
the intended consumer (e.g. general population, vulnerable population);
disposition options (e.g. animal feed, destruction (burial, burning), reprocessing (heat treatment,
filtration), alternative storage conditions (such as freezing and use under specified conditions) etc;
the risk associated with the proposed disposition option and how these risks will be managed;
the location of contaminated product and the disposition premises/area;
the date and time the proposed disposition would occur;
conditions and controls for the method of disposition;
the requirements or constraints of other legislation e.g. the Resource Management Act 1991.
Refer to Appendix 3 for an example of a form that can be completed as part of this disposition assessment.
The completed form can be held on file and made available to the verifier, Food Compliance Officer or MPI on
request.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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9
Prevention of future contamination
9.1 Actions to prevent reoccurrence
Implement actions to minimise the chances of the recurrence of L. monocytogenes contamination. Refer to
Table 10.
Table 10: Possible preventative actions to take to minimise contamination
Possible causes of contamination
Possible action
Ineffective cleaning
Modify and validate the cleaning and sanitation programme
Failure at a CCP, or controls around separation or the
movement of equipment in and out of high care areas
Review the procedures and train staff to ensure that they
have a good knowledge of their responsibilities
Fault in the processing equipment
Repair or replace the equipment, where necessary
revalidate and test to ensure that the process is under
control
Found a harbourage site inside equipment or facilities
Eliminate the site. Dismantle the equipment and/or
subjecting it to a process that will kill the bacteria; or by
adding a new step to the routine cleaning and sanitation
procedure such as steam treatment or heating the
equipment in a moist oven overnight. If a niche remains
where the bacteria can persist even after intensive cleaning,
the equipment and/or facilities should be modified, replaced
or renovated to eliminate the niche
Contaminated ingredients
Review the validated process or acceptance testing or
supplier contracts
The product formulation permits the growth of L.
monocytogenes
Reformulate the product
The product is contaminated after the listericidal step
Add an additional lethality step or review and improve
process hygiene
9.2 Review of L. monocytogenes management controls after the
event
It is strongly recommended to review the procedures for the Listeria control measures after a L.
monocytogenes contamination event. The event should be formally closed out and relevant staff debriefed.
As part of a review consider the:









access/entry restrictions between areas, including compliance with personnel hygiene requirements
and the movement of equipment between areas;
cross-contamination potential between the process areas and product contact surfaces;
cleaning and sanitation programme, including the chemical concentrations and contact times;
processing and product handling procedures;
validated controls (where identified as a cause of the contamination);
sanitary design and condition of the facilities and equipment;
effectiveness of testing programmes (environmental and product);
Listeria management programme to confirm that it is appropriate and complete;
procedures around the management of the contamination event, including the recall procedures;
where used.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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9.3 Documentation, records and reporting
Keep records and document the actions taken during the contamination event.
Maintaining records is an important way of demonstrating that you took the appropriate action, will assist to
review of response plan, and can be provided as a record of your actions by a customer or regulatory body.
All records should be made available on request from the:



verifier;
Food Safety Officer;
Food Compliance Officer or MPI.
For RMP operators the records should be kept for at least four years.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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Appendix 1: Sample taking and testing during a contamination
event
Figure 3 provides a simplified time line in relation to the level of microbiological sampling that would be
expected following a L. monocytogenes detection. The blue line represents the level of sampling that is
undertaken when the process is under control and how this increases if there is a contamination event.
After a number of clear results are received the sampling then reverts to routine testing levels after the event.
The green line represents an intensive level of environmental sampling to try to identify a contamination
source. This high level of sampling may be continuous until the source is found or may be undertaken in
bursts, with an opportunity for the results to be analysed in between.
Figure 3: Time line of microbiological testing following a contamination event
*
Investigative Sampling
Level of microbiological testing
*
*
*
Contamination
event?
Routine monitoring
Routine monitoring
Intensive product and
environmental sampling
L.monocytogenes
.
detected on product
or product contact
surface
Ministry for Primary Industries
3 consecutive
days of no
detection for .
L.monocytogenes
Time
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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Appendix 2: Sample selection for testing product
The following is an example of how samples of product in store or that have been held or recalled by the food
operator should be sampled for testing. The example is given for n=60, but the same principles would apply
where a lesser number of samples are to be taken e.g. n=30 or n=15.
Sampling each batch of product using the following sampling plan provides 95% confidence of detecting at
least one case where the contamination level in the batch is 5%. Absence of L. monocytogenes in 25g where,
n=60, c=0 and m=0.
Product samples may be composited4 for the purposes of microbiological analysis (provided enumeration is
not required). A maximum of 15 25g samples may be composited and the whole composite sample should be
enriched.
Compositing of samples
 All compositing should be done by the laboratory.
 60 samples may form 12 composite samples made up of five individual samples (or 5 composite
samples of 12 individual samples) for the purposes of laboratory analysis. Laboratory results
should report presence or absence of L. monocytogenes in a 125g or 300g sample. It is important
to confirm with the laboratory that they are able to test composites, especially the larger volumes.
 When the composite sampling of on hold or recalled product is required, only unopened packages
of product should be submitted to the laboratory.
 Alternatively where there are large cartons of product, individual samples could be taken aseptically
by the food operator at the premises. Care should be taken to ensure that the equipment and
packaging material used does not contaminate the product.
Sample selection
Samples should be selected using a random sampling system. For example, the total number of cartons in
each batch should be known prior to computing the sampling plan. Each carton in the batch is then issued
with a sequential number and the required numbered cartons randomly generated5. For example:
 Take as a batch, all product processed and packaged on the same line on a particular working-day.
 Determine where this product is held and the total number of cartons.
 Assign each carton in the batch a sequential number.
 Using random number tables (or other means), generate 60 random numbers.
 A sample should be taken from each of the 60 cartons corresponding to the random numbers.
 Any carton which fits the parameters of the batch but which was not included in the batch at the
time of sampling should not be considered as part of that batch (i.e. as a late entry) for the
purposes of release.
 Use of results from retesting product previously found to contain L. monocytogenes (i.e.
contaminated product) is not permitted other than for the purpose of providing trace back
information.
The compositing of samples may not be applicable for certain products, e.g. non-instantised milk powders. Further information is available on the MPI
website (www.foodsafety.govt.nz) [Guide for the compositing of seafood samples for microbiological analysis
(http://www.foodsafety.govt.nz/elibrary/industry/Guidance_Compositing-.pdf)].
4
A simplified approach to sample selection is as follows:
Establish the number of pallets or cartons produced (if it was less than one pallet)
Ensure that samples are taken from all pallets or (if there are more pallets than the required number of samples) ensure that sampling is evenly
distributed over all of the production).
Where multiple samples are taken from the same pallet then they should be taken from different levels to ensure an even distribution
5
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
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Appendix 3: Product Disposition Form
Food operator:
Registration/Approval Number:
Date:
Contact Person:
Contact person signature:
Phone
Mobile:
Fax
Email:
L monocytogenes limit that applies to the product(s):
Level of L. monocytogenes in the product(s) (if known):
Illness details (symptoms, number of consumers affected) (where applicable and known)
Details of contaminated or potentially contaminated product(s) (attach more pages if needed):
Product
Name/Brand
Identification
details e.g. Batch
codes
Dates of
manufacture
Use-by / Best before
dates
Shelf life
Quantity
Location(s) of contaminated or potentially contaminated products:
Details of Distributors, Retailers, and Manufacturers to whom this product has been distributed:
Results of routine testing available?
Yes
No
Trend analysis completed?
Yes
No
Any Additional Information – (For example, where the problem is isolated to an
ient, other supply chain members identified)
This record should be held on file and provided to MPI, the Food Compliance Officer or verifier on request.
Ministry for Primary Industries
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Guidance Document: Guidance for the Control of Listeria monocytogenes in Ready-to-eat Foods Part 4: Corrective Actions
13 February 2017
Food operator:
Registration/Approval number:
Date:
Contact Person:
Signature of contact person:
Phone
Mobile:
Fax
Email:
Details of contaminated or potentially contaminated product(s)
Product Name/Brand
Identification details
Dates of manufacture
e.g. Batch codes
Use-by / Best
before dates
Quantity
Location(s) of contaminated or potentially contaminated products:
Method being used to hold the contaminated products (if any):
Physical
Labelling
Segregation
L monocytogenes limit that applies to the product(s):
Electronic
Other
Level of L. monocytogenes in the product(s) (if known):
Intended disposal option
Destruction
Reprocessing for human consumption
Animal consumption with or without reprocessing
Non-food or non-animal feed
Other
(state):____________________________________________________________________________________________
(state method, transportation and final location details of destroyed products or final product type and intended market):
Justification to support disposal options:
(attach data to support disposal option, e.g.; investigative findings, laboratory test results, trace back findings, corrective
actions, other relevant documents).
Records of disposal (including traceability of reprocessed product):
Ministry for Primary Industries
Attached
Page 33 of 33
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