Pathogen Environmental Monitoring – 25/03/10

Pathogen Environmental Monitoring (PEM) is an important part of the quality and food safety management systems in the manufacturing environment for high risk products. The products concerned are usually ready to eat such as dairy, ready meals, and meats but also those that will readily support bacterial growth such as gelatine. It is a fundamental requirement in many audit protocols for these products.

PEM is the monitoring of pathogens in the manufacturing environment under normal operating conditions. The manufacturing environment excludes food contact surfaces but includes non food contact areas such as floors, walls, drains, overheads, equipment exteriors, aprons, etc. The pathogens usually targeted are Salmonella, Listeria, and E Coli although others such as Staphylococcus can be targeted if the manufacturing conditions selects for these e.g. high salt levels in the environment. It is important to stress under normal operating conditions because, in RQAs experience, this procedure is quite often confused with cleaning verification swabbing which focuses on food contact surfaces.

Requirements and instructions for PEM should be documented and available to those involved. The instructions should define:

• Applicable products and processes
• Sampling location, frequency and method of sampling e.g. swab, air samplers etc.
• Testing methodology
• Test results and acceptance criteria
• Corrective action plans

PEM data can be used as a verification tool. It can confirm the effectiveness of many prerequisite programmes such as:

• Environmental practices
• Infrastructure and equipment design
• Personnel training

The information it provides about the environment is used to enhance practices, eliminate sites of infection and correct potential design problems before they pose a risk to the product. It is a proactive procedure that minimises food safety risks.

A number of plants risk assess the effect of pathogens in the environment and modify their response to a positive result accordingly. The manufacturing environment is divided into zones appropriate to the risk. The system typically consists of three zones:

• Zone 1 - Non product contact surfaces but close to food contact surfaces e.g. exterior of equipment, control panel buttons, aprons, tables etc. A typical response here would be to clean and reswab such that 3 consecutive negative are obtained together with restricted line operations and/or increased product monitoring and cross contamination precautions (glove changes) until clearance is given.
• Zone 2 - Remote non product contact areas within the high risk area such as floors, walls, drains, leg supports, wheeled items, etc. A typical response here would be to clean and reswab the affected area such that three consecutive negatives are found.
• Zone 3 - Remote areas outside of the high risk area where the product is produced e.g. hallways, doors, canteens, changing rooms etc. A typical response here is to clean the affected area and reswab and if found negative continue with the programme.