Effect of heat treatment onCronobacterspp.in reconstituted, dried infant formula: preparation guidelines for manufacturers

AIM: To explore safe guidelines for manufacturers and consumers to prepare, handle and store dry infant formula (DIF) to protect infants against Cronobacter spp. METHODS AND RESULTS: Selected strains (2.45, FSM 293, ATCC-12868, FSM-271) screened from 68 strains of Cronobacter spp. were used to study growth and survival in commercial DIF. Prototype growth patterns in Enterobacteriaceae enrichment broth (EEB) containing a cocktail comprised of ATCC 12868, ATCC 29004, ATCC 29544 and ATCC 51329 showed a rapid increase in cell count (2.0 log(10) to 6.2 log(10) CFU ml(-1)). Infant formula provided a better protective environment for the cells of Cronobacter strains than did buffered peptone water. Experiments on survival in inoculated (10(4)-10(6) CFU ml(-1)) reconstituted infant formula (RIF), preparation temperature, the effect of preparation volume (one-serving or two-serving) and effect of storage at room temperature for up to 10 h provided information to develop consumer guidelines for DIF preparation and handling. CONCLUSIONS: Reconstituted DIF in water at >70 degrees C in larger volumes, minimizing storage time before feeding and storing unused reconstituted formulate at <4 degrees C, may reduce the risk of Cronobacter infection in infants. SIGNIFICANCE AND IMPACT OF THE STUDY: Meningitis, necrotizing enterocolitis and bacteremia in premature babies has been linked to contaminated milk powder and DIF; better handling practices may improve the safety of these foods for neonates.