cronobacter bacteria microorganism


  • Cronobacter are Gram-negative, motile, rod-shaped, non-sporulating bacteria. Formerly known as Enterobacter sakazakii, it is believed to have been first recorded in a 1961 report describing the isolation of uniquely yellow-pigmented microorganisms from neonates suffering from fatal meningitis.

    Cronobacter can be found naturally in the environment, but these bacteria can survive for prolonged periods in low-moisture foods. In fact, Cronobacter has been isolated from powdered infant formula, rehydrated infant formula and utensils used to prepare infant formula, making the bacterium especially risky for newborn infants.

  • Cronobacter has also been found in powdered milk, herbal teas and starches, as well as powdered protein and dietary supplements. It has been isolated from food processing facilities and has occasionally been found by health officials in places like sewer water.
    Cronobacter can cause wound infections or urinary tract infections in people of all ages. In immunocompromised adults and the elderly, it can lead to bloodstream infections.

    While the Centers for Disease Control and Prevention (CDC) reports few cases of Cronobacter infection each year, with infants, Cronobacter can cause dangerous bloodstream infections or infections of the linings surrounding the brain and spine (meningitis) and can cause death. Infection in infants two months of age and younger most likely leads to meningitis. The first symptom of Cronobacter infection in infants is usually fever coupled with lack of appetite, crying or low energy.

Outbreak Threats and Methods of Detection

  • Recent Cronobacter infections and outbreaks involving powdered infant formula have occurred in the U.S., France and Mexico. Powdered infant formula is not sterile and its nutrients provide good conditions for the preservation and growth of Cronobacter after reconstitution. There have been reports, in fact, of these bacteria surviving in powdered infant formula for up to two years. 

    Since the pathogen does not survive pasteurisation used in powdered milk production, it has been suggested that Cronobacter contamination mainly occurs following the spray drying step of manufacturing. Experts speculate this is either due to a contaminated post-drying environment or addition of heat-sensitive ingredients after pasteurization. 

    For food manufacturers, there are various approaches, including culture-based and rapid methods, for identifying Cronobacter, and certain regulatory authorities such as the U.S. FDA and International Organization for Standardisation (ISO) have developed methods for Cronobacter detection.

    From a consumer perspective, it is important to keep powdered formula lids and scoops clean and to close containers of infant formula or bottled water as soon as possible. All baby bottles and other feeding items should be carefully cleaned, sanitised and safely stored. Powdered formula should be used within two hours of preparation unless refrigerated, and refrigerated formula should be used within 24 hours. Any unused formula from a feeding should be thrown away.