Food microbiology and pathogen testing: how to get lab quotes

Step 1: Decide what you're testing and why

• Finished product testing: to support a certificate of analysis, a customer requirement, or a hold-and-release program where product ships only after results come back
• Ingredient testing: to verify incoming ingredients that carry a known hazard
• Environmental monitoring: swabs or sponges from surfaces in the plant, to find contamination before it reaches food
• Water testing: for water used as an ingredient or for cleaning
• Validation or investigation: checking a new process, or tracing the source of a positive result

Why you test drives everything else: which organisms, how many samples, and how fast you need answers.

Step 2: Pick the tests

Pathogens (usually reported as detected or not detected in a stated sample size)

• Salmonella
• Listeria monocytogenes, or Listeria species for environmental screening
• E. coli O157:H7 and other Shiga toxin-producing E. coli, for some products
• Others where your hazard analysis points to them, such as Staphylococcus aureus or Bacillus cereus

Indicator and spoilage organisms (usually counts)

• Aerobic plate count
• Coliforms and generic E. coli
• Enterobacteriaceae, common for dry and low-moisture foods
• Yeast and mold

If you don't know which tests you need, your food safety plan or process authority should say. Labs can suggest a panel, but they can't write your plan.

Step 3: Understand when testing is required

• Preventive controls. Under FDA's preventive controls rule, a facility has to run environmental monitoring when contamination of a ready-to-eat food with an environmental pathogen is a hazard that needs a preventive control, for example when ready-to-eat food is exposed to the plant environment before packaging and gets no later kill step. Product testing is a verification activity the plan uses where appropriate.
• Listeria. FDA's draft guidance on Listeria in ready-to-eat foods recommends environmental monitoring for Listeria species on food-contact and non-food-contact surfaces, with corrective actions after positives.
• Accredited labs for specific cases. FDA's laboratory accreditation rule (LAAF) requires an accredited lab only for certain tests, such as some import testing and tests FDA orders directly. Most routine testing for a small manufacturer isn't covered, but customers often ask for a lab accredited to ISO/IEC 17025 anyway.

Sources: 21 CFR 117.165 (verification, environmental monitoring) · 21 CFR 1.1107 (LAAF scope)

Step 4: Send labs a request they can quote

• Product or sample type (finished product, ingredient, swab, water) and a short description
• Tests needed, or the reason for testing if you want a recommendation
• Sample size per test (for example the weight a pathogen test should cover) and whether samples can be composited
• Number of samples per week or per lot, and how often
• Turnaround you need, and whether you need a presumptive result first
• How samples get there: courier, overnight shipping, or lab pickup
• Report format: certificate of analysis per lot, online portal, or data export
• Accreditation required by your customers

Step 5: Compare lab quotes line by line

• Price per test, and whether it's per sample or per composite
• Method (for example a recognized reference method or a validated rapid method) and whether the lab is accredited for it
• Turnaround for negatives and for confirmed positives, which take longer
• Sample kits and shipping: included, extra, or billed by the lab
• Rush fees, weekend receiving, and cutoff times
• Volume pricing if you test every lot or swab every week
• Reporting: portal access, certificate format, and how positives are communicated

What drives micro testing prices

• The organisms tested and the method (rapid methods and confirmation testing add cost)
• Sample size and compositing
• Turnaround speed and rush requests
• Volume and test frequency
• Accreditation scope
• Shipping and sample handling

What drives turnaround

• The method: some tests need enrichment and confirmation steps before a result is final
• Positive results, which need confirmation
• Shipping time and the lab's receiving cutoff
• Lab queue and weekend operations

Ask each lab for its current turnaround for negatives and for confirmed positives.

Questions to ask a food micro lab

• Which tests and methods do you recommend for my product and purpose?
• Are you ISO/IEC 17025 accredited for those methods?
• What sample size does each test cover, and can samples be composited?
• What's the turnaround for a negative result, and for a confirmed positive?
• What's included: sample kits, shipping labels, courier pickup?
• How do you report results, and how do you notify me of a positive?
• What volume pricing do you offer for routine testing?

How PostRequest helps

Tell us what you need tested, how often and how fast once. Our agents shortlist food testing labs, email each one your request from a PostRequest address, follow up once, and line up the replies: price per test, methods, accreditation, turnaround, and what's included. Labs see your testing needs, not your name or company, until you choose to connect. During early access, a person on our team reviews every comparison before it reaches you.