The presence of Enterobacter sakazakii in powdered infant formula has been of serious concern because of recent outbreaks of infectious diseases. The FDA has determined that powdered infant formula has been the source of one-half to two-thirds of the infections caused by this bacterium. One study that sampled 141 cans of various brands of powdered formula concluded that E. sakazakii was present in 14 percent of the samples. In 2002, the FDA recalled 1.5 million cans of powdered infant formula because of possible contamination.
Explore this issueApril/May 2005
Enterobacter sakazakii is a gram-negative, rod-shaped member of the Enterobacteriaceae family. It has been implicated in rare, but potentially life threatening outbreaks of necrotizing enterocolitis, sepsis, and meningitis, mostly among premature infants and newborns. As many as a third of those affected die, and survivors may experience serious, chronic health problems such as severe digestive disorders, organ damage, hydrocephaleae, quadriplegia, and retarded neural development. The outbreaks in neonatal intensive care units worldwide have been of such concern that the FDA has instituted strict regulations for the use of powdered formula in neonatal intensive care units in the United States.
Need for Improved Method of Bacteria Removal
Powdered formula undergoes intensive heat treatment during processing to remove bacteria. The processed formula must meet the criteria set by the FAO/WHO Codex Alimentarius Commission for the presence of coliforms, including Enterobacter sakazakii. This criteria, which applies internationally, is less than 10 colony-forming units per gram (<10 cfu/g) of powdered formula. A problem is that one of the E. sakazakii phenotypes has demonstrated exceptionally high thermal resistance (more than three times that of other enterobacteriaceae). This may explain why some E. sakazakii remain in the powdered infant formula, even after heat treatment.
The E. Sakazakii bacteria remaining in this nonsterile formula, though at low levels, can cause infection. And these bacteria can survive in the formula powder for up to 24 months. Besides, scientific literature has shown that drastic heat treatment of powdered infant formula has numerous undesirable effects. It can cause poor nutrition and chronic inflammatory reactions, which themselves can bring about other health conditions. The higher the temperature at which the formula is processed, the greater the nutrient loss. Particularly affected are the solubility and nutritional value of proteins. When Maillard reaction occurs, irreversible changes in protein structure, irreversible interactions with sugar, and salt imbalance result. In the early Maillard reaction, there is a reduction in essential amino acids such as lysine and tryptophan. Powdered infant formula contains 20-25 % less lysine than breast milk. Since lysine is an essential nutrient, formula is enriched with proteins, and enriched formula has been linked to obesity. In the late Maillard reaction, carboxymethyllysine (CML) is produced. This molecule is known to cause chronic inflammatory reactions that can lead to sensitivities and allergies. Powdered infant formula has twice as much CML as fresh cow’s milk.
Out With the Old…
Manufacturers of powdered infant formula are committed to providing a safe, high quality product and have responded to the challenge of eliminating E. sakazakii by implementing more stringent process controls. These include the use of extremely rigorous hygiene practices, labels with explicit instructions for product preparation, and specific measures to satisfy HACCP. Additionally, most manufacturers have developed more stringent microbiological standards than those of the FDA and the FAO/WHO Codex Alimentarius, namely no coliform cells in 25 grams (0 cfu/25g) of powdered formula. While implementing this standard has probably helped reduce outbreaks, evidence shows that it has not completely eliminated them1. This is the reason why, to fully address the problem, the production process itself must be looked at.