THERMAL-RESISTANCE OF ENTEROBACTER-SAKAZAKII IN RECONSTITUTED DRIED-INFANT FORMULA

Enterobacter sakazakii, designated a unique species in 1980, has been implicated in a rare but severe form of neonatal meningitis, with drie d-infant formula being implicated as the mode of transmission. The hig h mortality rate (40-80%) and the lack of information about this organ ism led to a study of the heat resistance of Ent. sakazakii in reconst ituted dried-infant formula. Ten Canadian Ent. sakazakii strains (5 cl inical and 5 food isolates) were used to determine the heat resistance of this organism at 52, 54, 56, 58 and 60 degrees C in reconstituted dried-infant formula. D-values of 54.8, 23.7, 10.3, 4.2 and 2.5 min we re obtained for each temperature, respectively. The overall calculated z-value was 5.82 degrees C. In a comparison of the D-values of severa l members of the Enterobacteriaceae in dairy products, Ent. sakazakii appeared to be one of the most thermotolerant organisms. The importanc e of process control during manufacture and the use of aseptic procedu res during the preparation, use and storage of dried-infant formula is discussed.