Why Passing USP <61> Doesn't Mean Your Botanical Ingredient Is Safe: The Case for Specified Organism Testing

Passing a total count test is not the same as proving a product is safe. That distinction trips up more supplement brands than you’d expect — especially those sourcing botanical raw materials from international suppliers who include a certificate of analysis showing TAMC and TYMC results and little else.

USP <61> tells you how many microorganisms are present. USP <62> tells you which ones. And when it comes to Salmonella and E. coli in herbal ingredients, that difference can be the gap between a compliant product and an FDA-initiated recall.

What USP <61> and USP <62> Actually Measure — and Why They’re Not Interchangeable

Most quality professionals working in dietary supplements are familiar with USP <61> — the compendial method for enumerating total aerobic microbial count (TAMC) and total yeast and mold count (TYMC). Acceptance criteria for most oral non-sterile botanical raw materials sit at TAMC ≤ 100,000 CFU/g and TYMC ≤ 1,000 CFU/g, though specific limits vary by ingredient and intended use.

USP <62> is the companion chapter, and it covers something fundamentally different: the detection of specified (objectionable) organisms that must be absent or present below defined thresholds. For oral, non-sterile dietary supplement ingredients, the standard specified organism panel typically includes:

• Salmonella species — absent in 10 g
• Escherichia coli — ≤ 10 CFU/g for finished oral products
• Bile-tolerant gram-negative bacteria (BTGN) — ≤ 100 CFU/g
• Staphylococcus aureus — ≤ 100 CFU/g, depending on product category
• Pseudomonas aeruginosa — required for topical and ophthalmic formulations

The applicable organisms and limits are product-category-specific. Table 5 in USP <62> provides the full matrix; an oral capsule formulation follows different criteria than a topical botanical cream. It’s worth confirming your product category before ordering a panel, because a one-size-fits-all approach often misses something.

Here’s the part that matters most in practice: a raw material can pass every USP <61> criterion — total aerobic count well within limits, yeast and mold clean — and still return a Salmonella positive. The two chapters answer different questions. Running one and assuming the other is covered is a compliance gap that doesn’t become visible until an FDA inspection or, worse, a recall.

Why Botanical Ingredients Carry Unusual Microbial Risk

Herbal and botanical raw materials carry inherent microbial risk that refined pharmaceutical excipients simply don’t have. Most of that risk comes from the field, not the processing facility.

Botanicals are grown in open soil, often in regions where animal-derived fertilizers are standard agricultural practice and infrastructure for post-harvest sanitation is limited. The supply chains for ingredients sourced from South Asia, East Africa, and parts of Latin America can involve multiple handling steps — drying, milling, blending, bagging — each of which is an opportunity for cross-contamination before a sample ever reaches a North American receiving dock.

The piece that surprises sourcing teams most often: low water activity doesn’t kill Salmonella. Desiccated botanical powders — black pepper, turmeric, cumin, coriander, dried ginger — have been repeatedly implicated in Salmonella outbreaks precisely because the pathogen survives dehydration and can persist in low-moisture matrices for months. FDA has documented Salmonella contamination in botanical ingredients at concentrations well below 1,000 CFU/g. A batch with a TAMC of 8,000 CFU/g (comfortably within the 100,000 CFU/g limit) could still harbor a Salmonella positive. Total count data gives you no information on that.

The same logic applies to E. coli. Most E. coli strains present in a standard environmental sample are harmless indicator organisms. But the presence of any E. coli in a botanical raw material signals fecal contamination — which means pathogenic strains, including STEC, cannot be ruled out without additional testing. USP <62>‘s ≤ 10 CFU/g limit for oral products reflects the conservative stance the compendium takes on organisms that carry pathogenic potential even at low counts.

Herbs with complex surface morphology — root powders, bark pieces, leaf fragments — are also particularly difficult to decontaminate after harvest. Steam treatment and gamma irradiation can reduce microbial load, but both have regulatory and labeling implications that aren’t always desirable, and neither eliminates the need for incoming testing.

What 21 CFR Part 111 Actually Requires From Your Testing Program

Under 21 CFR Part 111, the cGMP regulation for dietary supplements, manufacturers must establish specifications for identity, purity, strength, and composition for every component used in production (§ 111.70). They must also perform laboratory testing — or otherwise verify — that components meet those specifications before use in manufacturing (§ 111.75).

FDA’s consistent interpretation: “purity” includes the absence of objectionable microorganisms. A TAMC result that falls within a numeric limit does not satisfy the purity specification if known organisms of concern — Salmonella, specifically — were never tested for. This is not a gray area. FDA has stated this position clearly in guidance documents and in warning letters.

Between 2019 and 2023, FDA issued more than 40 warning letters to dietary supplement manufacturers citing inadequate microbial testing of raw materials or finished products. In several of those letters, the agency noted that manufacturers had run total count tests but had not performed Salmonella or E. coli screening on botanical ingredients with documented contamination histories. “Documented contamination history” is language FDA uses deliberately — it identifies ingredient categories where agency surveillance data has repeatedly found pathogen contamination, and it signals that a manufacturer who doesn’t test for those pathogens in those ingredients is taking a risk the agency has already noticed.

Botanical raw materials that appear in FDA’s flagged ingredient data include ashwagandha root powder, dried ginger, black cohosh, licorice root extract, and various Ayurvedic herb blends. If any of these are in your formulations, a supplier CoA that lists Salmonella as “Not Tested” isn’t a clean bill of health — it’s an open question.

What the USP <62> Testing Protocol Looks Like in Practice

The USP <62> methods are more involved than a standard plate count, which is why turnaround time for specified organism results runs longer than for USP <61> data. Understanding what happens in the lab helps with quarantine planning.

Salmonella testing follows a multi-step enrichment protocol. The 10 g test portion is first pre-enriched in buffered peptone water (BPW) for 18–24 hours — this step allows injured or stressed Salmonella cells to recover and become detectable. The culture then transfers to a selective enrichment broth, typically Rappaport-Vassiliadis or tetrathionate broth, for another 18–24 hours. Selective enrichment suppresses background flora while amplifying Salmonella if it’s present. From there, the culture is plated onto two selective differential agars (xylose lysine deoxycholate and bismuth sulfite are common choices) and incubated for 24–48 hours. Suspicious colonies are confirmed biochemically or by PCR. Start to confirmed result: 4–6 days.

E. coli and BTGN testing uses a separate membrane filtration or MPN approach. Samples are filtered through a 0.45 µm membrane, which is transferred to MacConkey agar or equivalent selective media and enumerated after 24–48 hours of incubation. Characteristic colonies are confirmed by additional biochemical tests if needed.

A complete USP <61>/<62> panel on a botanical raw material typically returns results within 5–7 business days. That’s the quarantine window to build into your receiving process. Releasing a lot before testing is complete — even if it’s “expected to pass” — remains one of the more commonly documented cGMP violations in FDA 483 observations at supplement manufacturers.

What to Ask Your Analytical Testing Laboratory Before Submitting Samples

Not every contract lab runs a full USP <62> panel by default. When you’re vetting an analytical testing laboratory for microbial compliance work, a few questions clarify whether you’re getting compendial testing or something weaker:

Is USP <62> within your ISO 17025 accreditation scope? Accredited analytical testing laboratories are required to validate and document the methods within their accredited scope. Request the scope document, and confirm that USP <62> methods for your organisms of interest are included — not just referenced.

What test portion size are you using for Salmonella? The compendial requirement is a 10 g test portion. Some labs use smaller inputs, which reduces detection sensitivity and may not satisfy FDA’s expectation for the method. Confirm the portion size is documented on the CoA.

Does the CoA include method detail or just a pass/fail? FDA expects manufacturers to have documentation sufficient to reconstruct the testing. A CoA that says “Salmonella: Absent” is useful; one that also states the method (USP <62>), enrichment steps, and test portion size is defensible.

Is the specified organism panel matched to your product category? An ingredient destined for an oral capsule needs the oral non-sterile product criteria. A botanical extract going into a topical needs a different organism set. Confirm the lab is applying Table 5 criteria correctly for your use case.

At our Chicago sample receiving facility, we regularly see supplier CoAs from overseas growers that list Salmonella as “Tested: Pass” with no supporting method information — no enrichment protocol cited, no test portion stated. Those results require verification before we’d consider them sufficient for a 21 CFR Part 111 purity specification. The method matters as much as the result.

Practical Steps for Midwest Supplement Brands

If you’re a small to mid-size brand sourcing botanical ingredients through a distributor or directly from an overseas contract grower, the following steps translate the compliance requirements into operational terms:

1. Identify your high-risk ingredients. Cross-reference your formulation’s botanical inputs against FDA’s historically flagged ingredient categories. Any ingredient on that list should receive Salmonella and full BTGN testing on every incoming lot — not just during supplier qualification or periodic skip-lot.

2. Audit your supplier CoA fields. Verify that CoAs from your suppliers state the test method (USP <62> or an equivalent validated method), the sample size used, and the numerical or absence/presence result. A CoA that says only “microbiology: compliant” without method detail is insufficient for demonstrating specification conformance under 21 CFR § 111.75.

3. Build the 5–7 day testing window into your quarantine timeline. A receiving workflow that accounts for full microbial results before lot release is easier to defend in an FDA inspection than one that approves ingredients against supplier documentation while waiting for independent data.

4. Retain all testing records for at least 6 years. Under 21 CFR Part 111 § 111.415, records must be retained for 2 years beyond the shelf life of the batch, or a minimum of 3 years — whichever is longer. In practice, FDA investigations frequently reach back 5–6 years, and CoAs from that window are routinely requested.

The USP <61>/<62> distinction matters more for botanical raw materials than for virtually any other ingredient category in the supplement supply chain. Total count data is a hygiene indicator. Specified organism testing is the safety checkpoint. Running one without the other doesn’t constitute a complete microbial profile — and FDA is treating it that way in enforcement.

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Written by Nour Abochama, VP Operations, Qalitex | Quality Consultant, Ayah Labs. Learn more about our team

Ship your sample to our Chicago facility — get a Qalitex CoA in 5–7 days. Contact us

Related from our network

• USP <61>/<62> Microbial Testing and ISO 17025 Accredited Lab Services — Qalitex Laboratories performs compendial microbial testing for supplement manufacturers and raw material distributors under ISO 17025 accreditation.