Cronobacter sakazakii (formerly known as Enterobacter sakazakii) is a rare, though often fatal, cause of meningitis in newborns and infants.

Some history

Cronobacter sakazakii has gone through more than one name change. It was first described as a yellow-pigmented Enterobacter cloacae, then – in 1980 – assigned the species name Enterobacter sakazakii (Farmer, J.J. III, et al. 1980. Enterobacter sakazakii: A new species of “Enterobacteriaceae” isolated from clinical specimens. Internat. J. Systemic Bacteriol. 30(3): 569-584). The pathogen was linked to cases of neonatal meningitis for the first time in 1961 in a British report (Urmenyi, AM & Franklin, AW. 1961. Neonatal death from pigmented coliform infection. Lancet 1(7172): 313-315), and for the second time in a 1965 report from Denmark (Joker, R.N., et al. 1965. A case of neonatal meningitis caused by a yellow enterobacter. Dan. Med. Bull. 12:128-130).

What is Cronobacter sakazakii, and where is its natural habitat?

Cronobacter sakazakii is an opportunistic pathogen, affecting mainly newborns, and causes neonatal necrotizing enterocolitis and neonatal meningitis. In older infants, children and adults, it can cause sepsis and/or respiratory illness. The microbe has been found in many countries around the world, and has been recovered from Mexican fruit flies and the larvae of stable flies. It is found in food production facilities and households, and has been detected at low levels in powdered infant formulas in a number of countries.

How is Cronobacter sakazakii transmitted? What is the incubation period of the infection?

Cronobacter sakazakii infections of newborns have been traced to the use of reconstituted powdered infant formula, especially in hospital settings where formula is prepared in bulk and stored for several hours under refrigeration until needed. In neonatal intensive care units (NICU), feedings can take several hours, during which time the reconstituted formula remains at room temperature – a recipe for microbial multiplication. The incubation period for a Cronobacter sakazakii infection may be as short as one day or as long as three weeks; typically, infections show themselves within one week.

What illnesses are caused by Cronobacter sakazakii? How long does it take to develop?

Cronobacter sakazakii is a cause of necrotizing enterocolitis and meningitis in newborns. In older babies, children and adults, this opportunistic pathogen can cause respiratory infections and sepsis.

What are the symptoms of Cronobacter sakazakii infections?

Symptoms in newborns include fever, rapid heart rate, seizures and other neurological abnormalities.

What is the prognosis of Cronobacter sakazakii infections?

Cronobacter sakazakii infections are often fatal in newborns. The death rate has been reported to be as high as 40-80%.

What foods carry Cronobacter sakazakii?

Cronobacter sakazakii has been found at low levels in powdered infant formulas. It also can be found in water and the environment.

How can susceptible people protect themselves from infection?

The Illinois Department of Public Health offers the following advice:

Clean utensils

  • Wash hands, forearms and fingernails thoroughly before handling any feeding materials or preparing formula.
  • All bottles, nipples, caps and rings should be washed in hot, soapy water with thorough rinsing.

Preparing formula

  • Before use, powdered formula should be kept dry in an airtight container with a firm cap or lid and stored in a cool, dark area. Make sure the expiration date has not passed.
  • During formula preparation, bring water to a bubbling boil for two minutes and allow the water to cool before mixing.
  • Do not use a microwave oven to warm the formula.

Storing formula

  • Formula should be prepared in small amounts immediately before feeding time to minimize the need for storing reconstituted formula.
  • Reconstituted formula should not be stored at room temperature for more than one hour or more than four hours in the refrigerator after preparation.
  • Throw out any formula left in a bottle after feeding.

You can find more information on Cronobacter sakazakii and other food-borne pathogens in Food Safety: Old Habits, New Perspectives.