How did US baby formula get contaminated with dangerous bacteria?

By Carrie Arnold

Nearly half of the usual supply of baby formula in the US is currently out of stock.

That is according to the latest analysis from Datasembly, a company that analyses real-time product data. In the first half of 2021, baby formula stock was relatively stable, with out of stock rates between 2 and 8 per cent. But as supply chain issues made it harder to get hold of raw ingredients and staffing shortages interrupted production, those rates steadily crept up last year.

They continued to rise in early 2022. Then, in late January, after several reported cases of illness and two infant deaths, the US Food and Drug Administration (FDA) began an inspection of a plant in Sturgis, Michigan owned by the country’s largest formula manufacturer, Abbott Nutrition.

Inspectors discovered that Cronobacter sakazakii bacteria were present in the formula and on multiple surfaces in the facility. In mid February, while the investigation was ongoing, Abbott Nutrition announced a voluntary recall of formulas produced at the plant and halted production. The FDA also warned consumers not to use powdered infant formula produced at the facility.

On Monday, FDA Commissioner Robert Califf said the plant should reopen within the next two weeks.

How did the bacteria get into the formula?

“That’s the million-dollar question,” says microbiologist Séamus Fanning at University College Dublin in Ireland.

Although powdered baby formula isn’t required to be sterile, Fanning says that regulations require manufacturers to take great pains to eliminate all sources of contamination.

Many baby formulas use cow’s milk proteins, such as whey and casein, as well as fatty acids and sugar, often lactose. Most of these ingredients are added at an early stage of manufacturing, after which the formula is heat-treated to kill any potentially harmful bacteria.

But because certain ingredients, including things like iron and vitamins A and D, degrade at high temperatures, they are added after this step, says food microbiologist Aliyar Fouladkhah at Tennessee State University. So it may be that contamination happened at this stage, although its precise origin is still unknown.

How dangerous is C. sakazakii?

C. sakazakii can be found throughout the environment, says Fanning. In mild cases of illness, the bacterium causes symptoms such as stomach upset, fever and malaise. But in more severe cases, C. sakazakii can cause meningitis – inflammation of the fluid and membranes surrounding the brain and spinal cord, which is life-threatening for children under 2 months old.

“Infants are very vulnerable,” says Fanning. “And in many of those situations, the meningitis is fatal.”

The presence of C. sakazakii in powdered formula is especially concerning because of the bacterium’s ability to survive desiccation. By erecting a series of chemical barriers, it can preserve moisture inside the cell even as the world around it dries out. It can also form hardy biofilms that help it survive harsh, dry environments.

What is the safest way to prepare baby formula?

Suggested best practice varies between countries, and in some cases, even between authorities within the same country. In the UK, the National Health Service (NHS) has a detailed 13-step guide that includes using cooled, boiled water to prepare infant formula.

In the US, the CDC recommends washing hands, bottles and teats before preparation, using “water from a safe source” and following manufacturer guidelines about the proper amount of powder to add. It also advises using the formula within two hours or refrigerating it for no longer than 24 hours before discarding.

Lawrence Goodridge, a food scientist at the University of Guelph in Ontario, Canada says that the shortage may tempt parents to use formula after this time has elapsed but warns that this could increase a baby’s risk of becoming ill. He also recommends against using homemade formulas as these may lack the vital nutrients babies need and could be unsafe.

For caregivers of the most vulnerable babies, including premature infants, those under 2 months of age, and those with compromised immune systems, the CDC, NHS and World Health Organization offer similar guidance: heat water to 70°C to kill off potentially harmful bacteria, mix in the powdered formula and allow the bottle to cool before feeding it to babies.

But if baby formula is known to be contaminated, it needs to be discarded as there is no way to ensure that it is safe, says Goodridge.

Can parents struggling to find formula switch to breast milk?

There are many reasons people don’t breastfeed: they may have difficulty producing milk or getting the infant to latch, lack access to facilities or have work schedules that don’t permit feeding or pumping, or they may simply prefer not to. People who aren’t already breastfeeding can’t spontaneously begin milk production.

Some organisations run milk banks for parents to obtain pasteurised breast milk from pre-screened donors. Outside of such programmes, which may require a doctor’s prescription to access, it is difficult to monitor safe storage and potential contamination of donations.

For people in the US affected by the formula shortage, the American Academy of Pediatrics has issued guidance about what to do until formula is widely available again.

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