Recall Guidelines for Packaged Ready-to-eat foods found to contain Listeria monocytogenes  at point of sale

April 2001

Background:

There is an increasing concern world wide about Listeria monocytogenes as a major foodborne pathogen.   Recent large outbreaks, a high case fatality rate, and the fact that L. monocytogenes can be isolated from a wide range of foods at a time when there is an expanding population of highly susceptible persons means that there is a need for continual vigilance and surveillance.

Foods that have been most often associated with human listeriosis are ready-to-eat products that support growth of L. monocytogenes, have a long refrigerated shelf life, and are consumed without further listericidal treatments.  

These Recall Guidelines for Packaged Ready-to-eat foods found to contain L. monocytogenes have been developed in response to the need for a national approach for determining when ready-to-eat packaged products available for sale at retail level have an unacceptable level of contamination and should be recalled.  

Australian Food Standards Code

In the current Australian Food Standards Code(FSC) microbiological standards for L. monocytogenes,specify:

• 'not detected' in soft cheeses, cheeses manufactured from thermized milk, smoked fish products, smoked mussels, meat paste and paté.  

These standards apply to product sampled at the processing factory or wholesale level, and do not apply to product at retail level. 

Joint Australia New Zealand FSC

Microbiological standards for L. monocytogenes are also contained   in the new joint Australia New Zealand FSC.   Changes in the new standards for L. monocytogenes include:

• ' not detected' level for packaged cooked cured/salted meat and cooked crustacea;
• the ' not detected' level for soft cheeses and cheeses made from thermized milk changed to soft and semi-soft cheese;  
• the ' not detected' levels for smoked mussels, meat paste and paté, and smoked fish have been retained but the terminology changed to 'molluscs that have undergone processing other than depuration' , ' packaged heat treated meat paste and paté' and ' ready-to-eat finfish (other than fully retorted)' respectively.   In the latter, one sample out of five may contain up to 100cfu/g of L. monocytogenes;and
• there is a ' not detected' level for unpasturised milk and butter, where expressively permitted by States and Territories, and a ' not detected' level for raw milk cheese, where expressively permitted by the FSC.  

These new standards apply for the full shelf life of the product.

Microbiological guidelines

Microbiological guidelines are being developed to complement the microbiological standards and will   include a ' not detected' level for L. monocytogenes in pasteurised milk and cream, dried milk, ice cream, and infant cereals and formula and for cooked meats.

Responding to the finding of L.monocytogenes in foods for which there are not standards  L. monocytogenes may on occasion be found in a wide variety of packaged foods sampled at the retail levels and for which there are no standards.   The absence of qualitative and quantitative baselines for determining the risk that the presence of L. monocytogenes poses in these foods has been a problem for State and Territory Health Authorities who, when confronted with isolation of L. monocytogenes  must decide on an appropriate action (such as recall).   In the past, the detection of L. monocytogenes in any food product would often lead to a recall without any evaluation of the actual risk

Purpose:

These recall guidelines have been prepared to assist State and Territory Health Authorities determine when the presence/level of  L. monocytogenes in packaged ready-to-eat foods presents a risk to public health, which may warrant recall action.

Similar guidelines exist in the UK, Canada, Denmark and the EU.

These guidelines have been developed specifically for use by Environmental Health Officers for packaged product at retail level.  

A decision to recall should only be made after full consultation with the relevant State or Territory Health Officer.   In addition to these guidelines, State and Territory Health Officers should consult with the manufacturer on issues such as the extent of the contamination, channels by which the goods have been distributed, and the level to which distribution has taken place, and remaining shelf-life.   These factors and any history of illness should be taken into account in determining the appropriate recall level.

This document should be read in conjunction with the ' Government Health Authorities Food Recall Protocol' and ' Food Industry Recall Protocol, 5th Edition ' .

Action Levels:

Using the approach proposed by the EC, a concentration of L. monocytogenes less than 100cfu/g can be considered to be of low risk to consumers, although the possibility of infection from low numbers of L. monocytogenes, especially among the most susceptible population groups (young, old, pregnant, immunocompromised) cannot be discounted (EC, 1999).   However action levels lower than 100 cfu/g will need to be applied for those foods in which growth can occur due to the uncertainty that exists in the estimation of risk for the consumer.  

Thus an action level of detected in 25g (10 or >10/g if an enumeration method is used) will be applied to packaged ready-to-eat foods capable of supporting growth of L. monocytogenes,ready-to-eat foods that have been implicated in human listeriosis and foods consumed by high risk groups to ensure that these foods do not exceed a level of 100 cfu/g at the point of consumption.

A recall decision tree is provided in Attachment 1.

Limits of growth for L. monocytogenes have been outlined in the ANZFA Technical Paper on L. monocytogenes which can be found in Attachment 2.

Sampling:

These guidelines provide microbiological levels for consideration of proposed recall action but do not provide sampling plans for determining the acceptance/rejection of sample lots. The statistical validity of a microbiological examination increases with the number of field samples analysed.   For regulatory purposes, a minimum of 5 sample units from a lot is generally examined.   The size of the samples taken should also be adequate to enable appropriate microbiological analyses to be undertaken.   A minimum sample size of 100g/ml is commonly required.

A lot can be defined as a quantity of food or food units produced and handled under uniform conditions. This may be restricted to a food item produced from a particular production line or piece of equipment within a certain time period (not exceeding 24 hours).

Field samples taken for laboratory analysis may be limited in number such as, for example, a single sample submitted as a consumer complaint.   While the relative microbiological quality of the submitted sample can be made, it may not be representative of the lot from which it is derived.   Further samples may be required if an assessment as to the microbiological status of the lot is needed.

The ICMSF publication ' Microorganisms in Foods 2, Sampling for Microbiological Analysis: Principles and Specific Applications' (1986) provides detailed information on using appropriate sampling plans.

Usage:

For the purposes of these guidelines, ready-to-eat foods are defined as those not requiring any further processing to maintain their safety (will not receive a listericidal treatment) before consumption.   Processes suchaswashingormoderatereheating(<70 degrees C for 2 minutes) are not considered to be listericidal.

For the purposes of these guidelines the term ' packaged food ' means food that has been fully encased in a wrap or container by the manufacturer and is not intended to be unwrapped except by the final consumer of the product.

Food processed correctly and protected from contamination after processing should normally be able to comply with a not detected (less than or equal to 10cfu) in 25g criterion.   While a tolerance of 100 organisms per gram is given for packaged ready-to-eat Category 2 foods, the presence of L. monocytogenes in products produced by a process which is capable of achieving a Listeria-free product may indicate that the process is not totally under control.   Thus the detection of L. monocytogenes in these foods would be an indication of either inadequate processing or post-process contamination that should be investigated by the manufacturer.

The action levels proposed are for recall purposes only.   Manufacturers must still strive for nil tolerance in their packaged ready-to-eat products.

Food categories and Action levels

Category of food	Level ofL. monocytogenes	Action
Category 1  -   ready-to-eat foods requiring refrigerated storage and able to support the growth of  L. monocytogenes*;                    - ready-to-eat foods that have been implicated in human listeriosis (e.g. soft & semi soft cheeses, pate, cooked cold chicken, cold-smoked fish**) and/or which may be consumed by at risk groups, especially infants	Detected in 25g# (Method: AS/NZS 1766.2.16.1- 1998 for the detection ofL. monocytogenes)***	recall
Category 2 - all other packaged ready-to-eat foods	equal to or greater than 100 cfu per gram (Method: No AS/NZ enumeration method; see FDA BAM for example for possible methods)	recall

*       Factors such as freezing, pH, water activity, lactates and organic acids may inhibit the growth of L. monocytogenes.  When it is difficult to predict whether a given food is supportive of growth for L. monocytogenes within the stated shelf-life, the authorities may take a conservative approach and regard growth as possible, unless there is documented evidence provided by the manufacturer that the product does not support growth of L. monocytogenes.

**    The Joint Australia New Zealand Food Standards Codehas a sampling plan for cold-smoked fish that allows one out of five samples to contain L. monocytogenes up to 100 cfu/g.

*** Equivalent methods may be used AS/NZS 4659

^#           10 or >10/g if an enumeration method is used.

April 2001