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The rod-shaped bacteria that killed a Missouri infant this month have
infected at least 120 infants worldwide since 1958 and have been linked to
the use of baby formula in the past, public-health researchers say.
The potential for the bacteria, called Cronobacter, to infect infants
through powdered baby formula has only been known since the 1980s, said
Kieran Jordan, a microbiologist at the Moorepark Food Research Centre of
Ireland’s Agriculture and Food Development Authority, in a telephone
interview. Cronobacter ends up in powdered formula because it is well
adapted at surviving in very dry environments, he said.
The bacteria may grow rapidly if the powdered product, with even small
amounts of Cronobacter, is reconstituted in water that’s not hot enough to
kill it, Jordan said. Once in a child, the infection can target the brain
and spinal cord, causing swelling of the brain lining, health officials said.
“Once the baby powder is rehydrated it is a very rich environment for the
bacteria to grow,” said Jordan, who has published multiple studies on
Cronobacter.
The U.S. Food and Drug Administration advises boiling water for one minute
and then letting it cool before mixing formula. Studies suggest powder needs
to be mixed with water heated to at least 158 degrees Fahrenheit (70
degrees Celsius) to kill off bacteria, the agency says on its website.
‘Not Sterile’
Powdered infant formula is “not a sterile product,” said Chris Braden, who
heads the Division of Foodborne, Waterborne and Environmental Diseases at
the U.S. Centers for Disease Control and Prevention in Atlanta.
While formula sold as a liquid typically is pasteurized and “a very low
risk,” it’s also more expensive, he said. Powdered formula should be used
within a couple of hours of being mixed, and parents should remember to wash
hands and equipment like bottles and nipples before preparation.
Not taking safety precautions can lead to permanent damage, Braden said.
Even when children survive the infection, they may have neurological
deficits, including developmental delays and seizures, he said.
Proving infant formula caused a given case of Cronobacter can be difficult
because the bacterium is found “in the kitchen, in soil, even around the
house,” Braden said in a telephone interview. It takes a “quite intensive
investigation” to prove a cause, he said.
Mead Johnston Results
Mead Johnson Nutrition Co.’s (MJN) Enfamil Newborn was pulled from store
shelves by retailers last week after it was learned that a baby from Lebanon
, Missouri, had taken it before becoming sick and dying. The company’s
tests after the death showed no evidence of the bacteria in the same batch
of product as that being evaluated by U.S. regulators, Mead Johnson said in
a Dec. 25 statement.
State and federal regulators also are analyzing the case of an Illinois
newborn given formula who fell sick with the infection during a trip in
Missouri, and CDC officials yesterday confirmed a third Cronobacter
infection in an Oklahoma baby who was hospitalized. While the Oklahoma child
used powdered formula, it wasn’t the same brand and there’s too little
evidence yet to say what caused the illness, Braden said.
Wal-Mart Stores Inc. (WMT), one of the retailers who pulled the Mead Johnson
product from store shelves, said it would await the result of government
tests before taking further action.
The CDC in 2009 estimated the number of infants infected with the bacteria
and reviewed a 2008 Cronobacter outbreak in which two babies in New Mexico
were confirmed with the illness. One of the infants died and the other
survived with severe brain damage, according to the CDC’s Oct. 30, 2009,
issue of Morbidity and Mortality Weekly Report, an agency publication.
‘Only Risk Factor’
While investigators couldn’t pinpoint the source of the bacteria, infant
formula “was the only known risk factor in the two cases,” according to
the 2009 paper from the Atlanta-based health agency.
In 2001, a Tennessee baby died following progressive brain damage from
Cronobacter infection. The baby was given powdered formula from a batch that
was found to contain the bacteria, according to a study in the April 12,
2002, Morbidity and Mortality Weekly Report.
The incident prompted Mead Johnson to voluntarily recall the batch in March
2002, according to the CDC’s report. It also heightened awareness among
formula makers, said Susan Ricker, Mead Johnson’s director of global
quality services.
New Standards
“The industry started working with the regulators and the health officials
worldwide to make sure that new and effective standards for Cronobacter
testing were in place,” Ricker said in a telephone interview.
Mead Johnson now performs 2,300 “quality-control checks” on formula,
including tests for nutritional quality and microbiological contamination
mandated by U.S. and international standards, according to Ricker. The
company samples 300 grams of each batch for Cronobacter contamination,
equipment is washed regularly and there’s a system in place to identify “
critical control points” where bacteria could enter.
“Once we have released a batch, we are stating it is safe for our consumers
,” Ricker said.
The Glenview, Illinois-based company also takes steps to educate consumers
about safety, said Chris Perille, company spokesman, in an e-mail.
All labels indicate that powdered formulas aren’t sterile and shouldn’t be
fed to premature infants or those with immune problems unless under medical
supervision, he said. The labels also cover proper hygiene, use and storage.
‘Very Young Infants’
The bacteria, when found, usually will have infected babies that are
premature or have weak immune systems, said Mary Alice Smith, a toxicologist
at the University of Georgia.
“It does seem to be the very young infants that are most susceptible to it,
” said Smith, who has studied the bacterial infection and has received
research funding from Mead Johnson.
The blood brain barrier in newborn babies, as well as parts of the
gastrointestinal tract, may not be fully developed, making them more
susceptible to the bacteria than older children and adults, Smith said. |
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