A premature baby became ill after consuming formula made from powder in a neonatal ward in Tennessee. A culture obtained by the hospital tested positive for Enterobacter sakazakii (now called Cronobacter sakazakii), a rare, invasive bacteria that often leads to death in neonates. The baby died nine days after infection was identified. The Tennessee Department of Health and CDC investigated the source of the infection. Forty nine babies who had been hospitalied in the same neonatal intensive care unit (NICU) were enrolled in a cohort study. Nine of the babies were found to have E. sakazakii in their stool. The study showed a strong association between E. sakazakii infection and consumption of powdered infant formula, Portagen. Cultures from the Portagen tested positive for E. sakazakii. The NICU changed their policy and subsequently used only commercially sterile, ready-to use, liquid infant formula except in specific cases where powdered formula was needed. A designated formula mixing room was created.