The US Food and Drug Administration is sharing a new warning about the risks of probiotics for hospitalized preterm infants. The products have been linked with over two dozen reported adverse events since 2018 and one death in 2023, the agency said.
On Thursday, the agency announced it had sent a warning letter to Abbott Laboratories for its Similac Probiotic Tri-Blend product, which the FDA described as an unapproved new drug and unlicensed biological product based on statements on its website and in marketing materials. The company agreed to discontinue sales of the product, the agency said.
In a statement on Friday, Abbott said that the issue “pertains to a single probiotic additive” for Similac Probiotic Tri-Blend, and that the probiotic is used by fewer than 200 hospitals. It does not apply to Abbott infant formula products.
“Parents and caregivers can continue to find and use Similac infant formulas nationwide. This Warning Letter is not related to any manufacturing quality issue. This product has been used for the past several years and has had a strong safety profile,” the statement said.
Probiotics, which contain live bacteria or other microorganisms for health benefits, are commonly used in the United States as dietary supplements. However, dietary supplements are not subject to the rigorous FDA approval process.
In hospitals, probiotics are often used to help prevent necrotizing enterocolitis, known as NEC, a life-threatening inflammation of the intestines in preterm infants. According to Dr. Katherine Chetta, a pediatric neonatologist at the Medical University of South Carolina, the disease can affect up to 1 in 20 premature infants, causing about one baby each day to die.
The American Academy of Pediatrics says that about 10% of preterm infants receive probiotics while in neonatal ICUs, a number that’s steadily increasing around the country. They’re one of the “main tools” that health care providers use for NEC, Chetta said.
However, in a statement, the FDA said that there is “conflicting data” about safety and effectiveness of probiotics for prevention of necrotizing enterocolitis. It urged more “high quality clinical trials” that could provide definitive evidence.
“Adverse events in any infant following the use of a probiotic are a concern to the FDA. We especially want to make clear that products containing live microorganisms may present serious risks to preterm infants in hospital settings,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said in a statement.
Earlier this month, the FDA reported that an infant died after receiving the probiotic Evivo with MCT Oil. The product, manufactured by Infinant Health for use in hospital settings, contained the infantis subspecies of the live bacterium Bifidobacterium longum. The baby died after developing sepsis caused by the same species of bacteria.
In a warning letter, the agency cautioned health care providers that bacteria and fungi found in probiotics might put preterm infants at risk of “invasive, potentially fatal” infections. The product was recalled after the FDA sent the warning letter and is no longer available in the US.
The FDA emphasized that it hasn’t approved any probiotic products for infants of any age, and products haven’t been evaluated for safety, effectiveness or compliance with manufacturing and testing standards.
“With today’s message, we want to warn parents, caregivers and healthcare providers that if these products are used for the prevention or treatment of disease, they have not undergone the agency’s rigorous premarket process to evaluate their safety, effectiveness and quality for these medical uses,” Marks added.
The American Academy of Pediatrics also does not recommend the supplements for preterm infants.
“Given the lack of FDA-regulated pharmaceutical-grade products in the United States, conflicting data on safety and efficacy, and potential for harm in a highly vulnerable population, current evidence does not support the routine, universal administration of probiotics to preterm infants, particularly those with a birth weight of <1000 g,” according to a 2021 clinical report from the pediatrician group.
But some physicians are concerned by the FDA’s opposition to probiotic therapy.
For many infants being treated in hospitals, Chetta explained, antibiotic treatment can alter the ecosystem, or microbiome, of bacteria in a baby’s gut, killing “good” types of bacteria while leaving “bad” types, like E. coli. Probiotics can help reintroduce more diverse, healthy bacteria into the infant’s body — rebuilding the microbiome and staving off infections such as NEC.
For Chetta, there’s enough data supporting the use of probiotics, especially since hospitals like hers select probiotics that they say they’ve seen work.
“We have high confidence in the probiotics we use,“ Chetta said. “We know that the babies actually get less sepsis with probiotics, they get less NEC, they get less death. “The real concern was and is: When is the FDA going to approve a product?”
There’s about a 1 in 5,000 chance that an infant receiving probiotics develops sepsis, far lower than the chance of an NEC infection, Chetta said. When preparing to treat an infant with probiotics, she also gives parents a say in evaluating the risks — including that the treatments are not FDA approved — compared with its effectiveness. For her, those benefits far outweigh the harms.
“The answer is not just removing all probiotics,” she said. “The answer is finding a solution, a safe solution where our babies can get the medicines and supplements they need.”
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