ByHeart engaged a third-party laboratory, IEH Laboratories and Consulting Group, to screen, detect, and characterize C. botulinum from finished products, using a tiered analytical approach combining anaerobic enrichment, molecular screening, culture confirmation, and genomic analysis.

The researchers concluded that “indicator-based screening (such as SRC enumeration), even if it had been in place before the [ByHeart] outbreak, would not have prevented its occurrence.”

‘Gold-Standard’ Test Failed to Stop Infant Botulism Outbreak

SRC enumeration is used by several competitors to ByHeart—that is, smaller, independently owned organic formula brands that market their products as "wholesome" and "clean"—including Nara Organics, which is now embroiled in its own, ongoing infant botulism outbreak (and which shared a powdered milk supplier with ByHeart). In fact, Nara tested to ten times the international best practice recommended by ICMSF, which set a maximum level of less than 100 colony forming units per gram (CFU/g). Nara had set its specification at less than 10 CFU/g, and went as far as to test each batch of formula for SRC at three stages: raw ingredients, formula powder during production, and finished product. Still, SRC enumeration was unable to prevent the Nara Organics outbreak.

As of June 15, three babies who were fed Nara Organics formula contracted botulism, and the company recalled its product out of an abundance of caution based on early epidemiologic evidence. Product testing for C. botulism in Nara products is still ongoing.

The use of SRC enumeration is promoted by several infant formula manufacturers who use it as a voluntary effort to strengthen the safety of their products.

Novel Test Method is 1,000 Times More Sensitive

ByHeart’s new testing protocol layers two testing methods at three stages of production. It is built on the foundation of an ISO Standardized Method combined with a novel, fit-for-purpose test method that was developed by IEH Laboratories specifically to aid ByHeart’s outbreak investigation. Both test methods are polymerase chain reaction (PCR)-based.

The new testing protocol detects C. botulinum to 0.01 CFU/g, which is 1,000 times more sensitive than the limits of SRC enumeration, according to ByHeart.

The company says the new protocol has been essential in verifying the contamination and helping trace the root cause of the outbreak. The test protocol is part of the company's recently introduced action plan to enhance formula safety, which also involves expanded supplier audits and increased ingredient testing frequency, QR-enabled batch traceability, and the formation of an independent Food Safety Advisory Council.

“Science evolves, and so must we. While we utilized the industry-standard direct-plating SRC methodology, based on the best information available at the time, this outbreak shows that protecting babies means continuously reassessing our methods and strengthening them when needed. This new evidence shows that a long-used test, like SRC, is not a reliable indicator for Clostridium botulinum; we have a responsibility to acknowledge that openly and act on it,” said Devon Kuehn, M.D., ByHeart’s Chief Medical Officer and Chief Scientific Officer.