It is recognized internationally that breast milk is the best source of nutrition for infants. However, there are instances where it may be insufficient or not available and thus, may need to be supplemented or replaced. In those instances, one of the dietary options is the use of powdered formulae (PF). For the purposes of this document, “powdered formulae” include the following:

• Infant formulae and formulae for special medical purposes intended for infants, which serve as the sole source of nutrition;

• Follow-up formulae which are used in combination with other foods as part of the weaning diet of older infants and young children;

• Powdered formulae for special medical purposes for infants and young children, intended to partially replace or supplement breast milk, infant formulae or follow-up formulae;

• Human milk fortifiers used to supplement breast milk.

These products are to be distinguished from ready-to-feed liquid formulae that have been commercially sterilized. As dehydrated products, it is not possible using current technology to produce powdered formulae that are devoid of low levels of microorganisms, i.e., the products cannot be sterilized. Thus, their microbiological safety requires strict adherence to good hygienic practices during both manufacture and use. Two FAO/WHO meetings of experts on the microbiological safety of powdered infant formula considered cases of illnesses in infants associated with PF consumption either epidemiologically or microbiologically.

They identified three categories of microorganisms based on the strength of evidence of a causal association between their presence in PF and illness in infants: A) microorganisms with a clear evidence of causality, namely, Salmonella enterica6 and Enterobacter sakazakii; B) microorganisms for which the causality is plausible but not yet demonstrated, i.e., they are well-established causes of illness in infants and have been found in PF, but contaminated formula has not been convincingly shown, either epidemiologically or microbiologically, to be the vehicle and source of infection, e.g., other Enterobacteriaceae; and C) microorganisms for which causality is less plausible or not yet demonstrated, including microorganisms, which despite causing illness in infants, have not been identified in PF, or microorganisms which have been identified in PF but have not been implicated as causing such illness in infants, including Bacillus cereus, Clostridium botulinum, C. difficile, C. perfringens, Listeria monocytogenes and Staphylococcus aureus.

Salmonella is a well-known long-standing foodborne human pathogen. The incidence of salmonellosis among infants, originating from various sources, was reported to be more than eight times greater than the incidence across all ages in the United States of America (CDC, 2004). Infants are also more likely to experience severe illness or death from salmonellosis, and infants with immunocompromising conditions are particularly vulnerable. It is unclear whether the increased incidence of salmonellosis among infants results from greater susceptibility, or whether infants are more likely than persons in other age groups to seek medical care or have stool cultures performed for symptoms of salmonellosis.