First, one should be aware and somewhat knowledgeable about the FDA Investigations Operations Manual (IOM) and within that, Chapter 4. Sampling.
The author of the Food Safety Magazine article points out keys of what FDA within their environmental sampling regiment may do that may be different than what a company's sampling plan may do.
- "They will not tell you that they are going to sample, until they are ready to start"
- "They are going to sample food contact and indirect contact surfaces"
- "They are not going to sample floors and drains"
- "They are going to sample during production, with a target of four hours of activity after a wet clean"
- "If a positive is found, they are sending it out for identification, adding it to the U.S. Centers for Disease Control and Prevention (CDC) database, and cross-referencing for any outstanding or past food safety incidents."
Selected items from 4.3.7.7.1
INVESTIGATIONS OPERATIONS MANUAL 2022 (https://www.fda.gov/media/75243/download)
4.3.7.7.1 - Environmental Sampling
- Every effort should be made to conduct Listeria sampling when the facility has been in production for at least four hours and before any wet cleaning is performed. In instances with smaller firms that have short production periods, swabbing should be conducted during the mid to tail end of their production schedule.
- In most cases, subsamples for Salmonella will be collected from the Zones 2 – 4 (see below), concentrating primarily on Zone 2. Samples should be collected from the equipment itself, particularly equipment mounting and support structures. When targeting Listeria, swabs will be collected primarily from Zones1 and 2. Perform most of the sampling for Listeria in, on, and around food contact equipment, focusing on areas where food is exposed and being processed, particularly post-treatment/pasteurization.
- A large majority of the environmental samples collected should be taken from Zones 1 (when directed and depending on the organism in question) and 2, and to a lesser degree Zone 3 areas. Very few, if any, environmental samples should be taken from Zone 4 areas.
- Swab subsample numbers for each organism are as follows:
- For Salmonella environmental swabbing, collect at least 100 swabs/subs and ideally 300 or more
- subs
- For Listeria environmental swabbing, collect at least 50 swabs/subs and ideally 100 or more subs.
Here are the FDA Zone definitions: