A tiny microbe gained national prominence at the end of 2011 when four US infants were diagnosed with Cronobacter infections. The children lived in Florida, Missouri, Illinois, and Oklahoma. Two of the children died from the infection.

The microbe is most lethal to the youngest infants, especially those born prematurely and those with weakened immune systems.

Cronobacter is a group of bacteria that are found naturally in the environment. It can survive in very dry conditions and has been found in dry foods such as powdered milk and formula, herbal teas, starches, and waste water.

Initially, factory contamination of powdered infant formula was suspected, but this was disproved following a thorough CDC investigation. It is most likely that the infants contracted the disease in their homes or communities, possibly from contamination of their formula powder after it had been opened up or from the use of contaminated water to mix it.

Cronobacter infections are rare. There were only 13 cases reported to the CDC in 2011. It can cause blood infections and meningitis and is most lethal to the youngest infants, especially those born prematurely and those with weakened immune systems.

In older children and adults, the bacteria can cause diarrhea, wound infections and urinary tract infections. The elderly and adults with weakened immune systems are also at higher risk of serious infections.

There are many ways to help keep babies safe from Cronobacter and other foodborne infections. The CDC notes that almost no cases of Cronobacter infections have been found in babies who were exclusively breastfed. They also note that liquid infant formula is sterilized during production and therefore should not be a source.

In order to avoid contamination of powdered formula during preparation, The CDC recommends the following steps:

  • Wash hands and work surfaces before preparing formula
  • Clean bottles in a dishwasher or hand wash and sterilize them
  • Keep powdered formula container lids, and scoops clean
  • Keep containers closed when not in use
  • Use hot water, 158° F, to make formula
  • Shake formula rather than stirring with a spoon to mix
  • Cool formula prior to feeding infant and test temperature on wrist

To be sure that formula doesn't become contaminated after preparation the CDC recommends:

  • Using formula within 2 hours of preparation and discarding unused formula remaining in feeding bottle
  • Refrigerate prepared formula if it is not going to be used immediately
  • Use refrigerated formula within 24 hours of preparation
  • Discard old formula.