Environmental Swabbing of Production Areas

The most common source of microbial contamination in a finished product is the processing environment.

Development and implementation of an effective environmental sampling program requires a basic understanding of microorganisms, the purpose of the sampling and how the data will be used.

Tailoring a program to fit the individual needs of the company is essential and requires judgment.

The reason for establishing the environmental monitoring programs drives the selection of sites, time of sampling and testing parameters.

A contaminated environment increases the risk of finished product contamination.

Sources of Microorganisms in Food Plants

  • Raw materials and ingredients
  • Air and aerosols
  • Water
  • Packaging material
  • Shipping material
  • Equipment
  • Facility Structures
  • Personnel
  • Insects, birds, rodents

Regulatory Requirements
Prerequisite programs
SSOP validation
Sanitation Verification
Ongoing and routine in nature
Distinct from SSOP validation
Risk Management
Identify growth niches
Hygienic design of facility and equipment
Potential post process cross contamination sites
Traffic and people flow issues
Personnel practices
Equipment maintenance and repair
Pathogen contamination of finished product
Product not achieving expected shelf life
Product not meeting microbial specifications
Routine monitoring results exceed established criteria
Routine Monitoring
Process Control
Alert to Developing Problems
Customer Requirements
Various as required by the Customer
  • What is the purpose of the sampling
  • Think like a bacteria – consider the basic principles discussed
  • Where is the product more at risk from the environment
  • Where are the more likely niche locations
  • Where are cleaning and sanitation activities more likely to be compromised
  • What practices increase the chances of growth niche creation, cross contamination, transport of microorganisms from on area to another, etc
  • Take into account the zone concept and assignment of the designated zones
  • There is no set standard for establishing frequency
  • What is the purpose of the sampling
  • What is the risk to the product
  • Initially established based on results obtained during initial risk assessments and surveys
  • Can be adjusted as the data is accumulated and trended
  • Rotation of sites
  • Common practice to identify a list of sites and rotate complete sampling of list over a period of time
  • Allow for out of rotation or additional sites based on observations of production environment by sampling personnel
  • Adverse results should always result in adjustment of frequency until resolution identified

Each group of microorganisms (gram positives, gram negatives, spore-formers, biofilm-formers) will have general characteristics relative to how they adapt and survive in the environment.

Microbial growth niches, a.k.a harborage site

  • Areas within the facility or equipment that allow ongoing propagation of microorganisms
  • Allows dispersion of the microbial population into the environment or equipment

Microbial biofilms

  • Bacteria attached to a solid surface that produce extracellular polymeric substances that enclose and anchor the bacteria to surfaces
  • The cells are protected from general cleaning and sanitizing efforts by the extracellular materials and are very difficult to remove once formed
  • Biofilms are considered a microbial growth niche

Often product and process dependent

  • Wet process
  • Dry process
  • Post CCP risk


  • Most often used to assess sanitation effectiveness or general sanitary conditions
  • Useful to develop SPC charts and evaluate trends
  • No correlation to the presence of pathogens
  • APC
  • Enterobacteriaceae
  • Coliforms
  • Yeast & Molds


  • Salmonella
  • Listeria – L. monocytogenes and L. species
  • E.coli O157:H7
  • Cronobacter sakazaki
  • Spoilage organisms
  • Directly related to product and process
  • General groups of organisms
  • Psychrotrophs
  • Thermophiles
  • Lactic acid bacteria
  • Fungi

Specific organisms rarely

Zone 1:  Product contact Surfaces
Slicers, Mixers, Conveyors, Utensils, Racks, Work tables, Filler heads
Zone 2:  Area immediately adjacent to contact surfaces that can directly contaminate product contact surfaces.
Exterior of equipment, Equipment housing, Framework, Food carts, Chill units, Ventilation equipment, Floors
Zone 3:  The area immediately surrounding zone 2 which can contaminate zone 2 by actions of humans or movement of equipment.
Corridors & doorways, Walls, Phones, Forklifts, Mules, Drains
Zone 4:  The area outside zone 3 and generally considered a remote area.
Locker rooms, Cafeteria/lunch room, Warehouse facilities, Loading/receiving dock, Hallways
  • Training of sampling personnel
  • Sampling tools
  • Sampling techniques
  • Sample site selection
  • Sampling frequency and numbers
  • Organisms of interest
  • Test methodology
  • Criteria or specifications
  • Data management

Educated in the concepts of aseptic sampling using aseptic techniques

  • Collection of samples using sterile materials and utensils
  • Practices and techniques that avoid/prevent contamination of sampling materials or samples
  • Gloves are for single use only – their purpose is to protect the sample from contamination, not to protect the samplers hands

Sampling protocols

  • General guidance often provided by manufacturer of supplies
  • FDA/ORA has training guidelines for investigations
  • ISO 18593:2004 provides a general platform for critical steps in the sampling procedure

Organized and prepared

  • Identify sampling sites prior for routine monitoring
  • Fill out as much information on records or labels as much as possible
  • Single sample for each location – do not use same sponge/swab for multiple locations
  • Apply pressure to remove organisms
  • Use both sides of the sponge to optimize recovery and surface area sampled
  • Begin sampling in the “cleanest” production areas and move backward through the higher risk areas

Maintain integrity of the samples prior to testing

  • Close and seal containers with samples
  • Maintain at ambient temperature for minimal time
  • <1 hour if quantitative testing involved
  • 1 – 2 hours for pathogens
  • Hold in refrigeration (2 – 7° C) until testing
  • If shipping to test site
  • Refrigerated, not frozen
  • Use appropriate coolers and ice packs (no dry ice or loose ice)
  • Testing initiated within 48 hours after sampling