Industry Information Session: Implementation of the 2011 Health Canada "Policy on Listeria monocytogenes in Ready-to-Eat Foods"
Topic 8: Industry Monitoring

Industry Monitoring

(Section 7 and Figures 1, 2 and 3 of the Listeria Policy)

  • Monitoring sampling is conducted to verify the effectiveness of the control measures which are used to eliminate, inhibit and prevent the growth of Lm
  • Sampling should include both: Environmental and End-Product

Industry Monitoring – Routine Environmental Sampling

(Section 7.2 of the Listeria Policy)

  • Test for the presence of Listeria spp. on both food contact surface (FCS) and non-food contact surface (Non-FCS).
  • The number of meaningful sample sites (preferably 10) depends upon the complexity of the processing system.
  • Environmental sampling for Listeria spp. helps verify the effectiveness of the GMPs/HACCP.
  • Presence of Listeria spp. on FCS could indicate that the controls (i.e., sanitation) are inadequate.
  • If Non-FCS samples (near to FCSs) are found positive for Listeria spp. on a regular basis, FCS should be tested more frequently.

Persistent contamination could be an indication of inadequate GMPs.

Industry Monitoring – End Product Testing

(Section 6.2, 7.3 and Table 1 of the Listeria Policy)

  • End-product sampling may be conducted for various reasons, including when FCS test positive for Listeria spp.
  • Testing may be required to verify RTE foods meet compliance criteria for Lm.
  • Samples submitted for Lm analysis should consist of 5 sample units of at least 100 g each.

Listeria Policy: Figures 1, 2 and 3

(Section 7.2 of the Listeria Policy)

Figure 1: Sampling Guidelines for FCS and Category 1 RTE food

Figure 2: Sampling Guidelines for FCS and Category 2 RTE food

Figure 3: Sampling Guidelines for Non-FCS

Figure 1: Sampling Guidelines for FCSs (Category 1 RTE Food)

Figure 1: Step A

Purpose is to determine if Listeria spp. is present

  • Collect FCS samples, as per MFLP-41
    • Collect preferably 10 FCS samples
    • Samples should be collected during production, typically 3 hours into production
    • Frequency and the number of sampling sites should reflect the manufacturing processes and controls
    • Special circumstances may warrant an increase in the frequency of sampling and/or the number of sample sites
  • Analyze samples either individually, or as composites
  • Use any enrichment (presence/absence) method for Listeria spp. published in HC's Compendium of Analytical Methods in which the "Application" section is appropriate for the intended purpose
  • FCS positive for Listeria spp.?
    • No, continue routine monitoring program.
    • Yes, proceed to Step B.

Figure 1: Step B

(Section 6 and 7 of the Listeria Policy)

  • Initiate corrective actions ASAP
    • Step B and onward should be recorded to include information on corrective actions, investigational sampling, product testing and/or disposition
    • Corrective actions:
      • Prevent or eliminate Lm
      • Control conditions that will enable growth
      • Be monitored to confirm effectiveness

Corrective actions should include

  • In-depth review of the food safety system (GMPs/HACCP) to ensure compliance and adjusting it, if necessary
  • Improvement in sanitation procedures
  • Identification of the source of the contamination through investigational sampling
  • After corrective actions are implemented:
    • All products from that line should be placed on hold
    • Collect FCS samples to verify efficacy of corrective actions, as per MFLP-41
      • At a minimum, the FCS sites in the routine monitoring program should be included
      • The number and location of samples sites should be adequate to verify that the entire line is negative for Listeria spp.
    • Analyze FCS samples individually
    • Use any enrichment (presence/absence) method for Listeria spp. published in HC's Compendium of Analytical Methods in which the "Application" section is appropriate for the intended purpose
  • (2nd) FCS positive for Listeria spp.?
    • No, resume routine monitoring program and release product put on hold at Step B.
    • Yes, test product as per Table 1, Listeria Policy and proceed to Step C.

Test product as per Table 1, Listeria Policy

  • End-product sampling should be linked to the environmental sampling
  • 5 sample units should be collected aseptically at random from the implicated lot
  • Each sample unit should consist of at least 100 g

Lm detected in 125 g – consult with regulatory authorities (e.g., CFIA) about disposition of product.

Lm not detected in 125 g – consult with regulatory authorities (e.g., CFIA). A health risk assessment (HRA) may be requested.

Figure 1: Step C

  • Notify regulatory authorities (e.g., CFIA) as soon as possible
  • Repeat Step B until FCS samples are negative for Listeria spp. and product samples are negative for Lm
    • Hold and test each lot of product until the results demonstrate that control of Listeria has been achieved
  • Sample FCS and end-product until results are negative for 3 or more consecutive production days and product samples do not exceed criteria for Lm

Figure 2: Sampling Guidelines for FCSs (Category 2 RTE Food)

  • Figure 1 and Figure 2 are very similar.

Figure 2: Step A

  • Step A is the same in both flowcharts; 10 samples from food contact surfaces would be collected and analyzed for the presence of Listeria spp.

Figure 2: Step B

  • However, in Step B, the two diagrams begin to look a bit different. Figure 1 recommends holding product produced on the implicated line following the first positive FCS sample, whereas Figure 2 recommends holding product produced on the implicated line after the second positive FCS sample. The Listeria Policy recommends that subsequent lots be put on hold after at Step C.

Figure 2: Step C

  • In Figure 1, end-product testing is recommended if a second FCS sample is positive, where as in Figure 2 end-product testing is recommend if a third FCS sample is positive. 
  • There is also a difference regarding the analysis and the action level for Lm between the two figures. For a Category 1 food, a regulatory authority should be contacted regarding product disposal if Lm is detected in 125 g. For a Category 2 food, these actions should occur if Lm exceeds 100 CFU/g at any point throughout the product's stated shelf-life. If the presence of Lm does not exceed these criteria, the facility should still be in contact with a regulatory authority, and a health risk assessment (HRA) may be requested.

Figure 2: Step D

  • Finally, Figure 2 has an extra step, Step D.
  • Determine if positives are due to processing conditions (possible HRA) or due to recontamination, continue intensified corrective actions until FCS are negative and review all results with regulatory authorities (e.g., CFIA).
  • For category 2 products, the company can resume routine monitoring sampling activities once FCS sample is negative for Listeria species and their respective product sample are negative for Lm or within the acceptable limits (Lmless then or equal to 100 CFU/g). The Listeria Policy states that product samples found with acceptable level of Lm not exceeding 100 CFU/g still may require an HRA, depending on different criteria (product intended for high risk population, or used in Category 1 product, remaining shelf-life of the sample, etc.). 
  • All positive results from Lm in a RTE food or persistent Listeria spp. on a FCS should be communicated ASAP to the regulatory authority (e.g., CFIA).

Figure 3: Sampling Guidelines for Non-FCSs, in Proximity to FCS (Category 1 and 2 RTE Food)

Figure 3: Step A

  • Collect non-food contact surfaces, as per MFLP-41 (either individually or as composites).
  • Non-FCS positive for Listeria species?
    • No, continue routine monitoring program.
    • Yes, proceed to Step B…

Figure 3: Step B

  • Initiate corrective actions as soon as possible.
  • Re-sample Non-FCS and analyze individually identify source of contamination and/or to verify efficacy of corrective actions.
  • Non-FCS positive for Listeria species?
    • No, resume routine monitoring program.
    • Yes, proceed to Step C…

Figure 3: Step C

  • Repeat Step B until Non-FCS samples are negative for Listeria species.
  • If Non-FCS samples are found positive for Listeria species on a regular basis, nearby FCS should be tested more frequently.

Industry Monitoring

(Section 7.4 of the Listeria Policy)

  • Trend analysis should be part of a company's verification process
  • Data can be used to model and predict risk
  • The results should be used to achieve improved control of Listeria over time
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