Cronobacter, which used to be called Enterobacter sakazakii, is a germ that can live in very dry places. Cronobacter has been found in dry foods, like powdered infant formula, powdered milk, herbal teas, and starches. It has also been found in sewer water. Cronobacter infections are often very serious for babies; they can die. Cronobacter infection can also be very serious for older people and people whose bodies have trouble fighting germs, like people with HIV, organ transplants, or cancer.

Getting sick from Cronobacter does not happen often, but infections in infants can be deadly. Cronobacter infections in infants less than 12 months old are often linked to powdered infant formula. If your baby is fed with powdered infant formula, you can take steps to protect your baby from sickness.

Cronobacter sakazakii is a germ found naturally in the environment.

These germs can live in dry foods, such as:

• Powdered infant formula
• Powdered milk
• Herbal teas
• Starches

Rare but Serious Illness in Infants

Cronobacter infections are rare, but they can be deadly in newborns. Infections in infants usually occur in the first days or weeks of life. About two to four cases are reported to CDC every year, but this figure may not reflect the true number of illnesses. That’s because most hospitals and laboratories are not required to report Cronobacter infections to health departments.

Cronobacter germs can cause a dangerous blood infection (sepsis). They can also make the linings surrounding the brain and spinal cord swell (meningitis).

Infants who are more likely to get sick include:

• Infants 2 months and younger. These infants are most likely to develop meningitis if they get sick from Cronobacter.
• Infants born prematurely.
• Infants with weakened immune systems. Babies with this condition can’t fight germs as well because of illness or medical treatment, such as chemotherapy for cancer.

Cronobacter illness in infants will usually start with a fever and poor feeding, excessive crying, or very low energy. Some infants may also have seizures. You should take an infant with these symptoms to a medical provider as soon as possible.

Cronobacter infection can also be serious for:

• People 65 years and older.
• People who have immune systems weakened due to illnesses or conditions, such as HIV, organ transplants, or cancer.

Powdered formula is not sterile and might have germs in it.

Powdered infant formula can be contaminated in homes or in processing facilities that make it.

In the home:

You can accidentally get Cronobacter in powdered formula after you open the container. Cronobacter can live on surfaces in your home, such as a kitchen counter or sinks, and in water. Cronobacter could get into powdered formula if you place formula lids or scoops on contaminated surfaces and later touch the formula. It can also get into formula if you mix the formula with contaminated water or in a contaminated bottle.

In a processing facility:

Cronobacter can also get into powdered infant formula in a processing facility in these ways:

• If the manufacturer uses contaminated ingredients to make the formula.
• If the formula powder touches a contaminated surface.

What is Cronobacter?

Cronobacter is a bacteria that has been found in a variety of dry foods, including powdered infant formula, powdered milk, herbal teas, and starches. It has also been found in water. Cronobacter illnesses are rare, but they can be deadly for infants and can be serious among people with weakened immune systems and people 65 years and older.

Cronobacter multi-species complex (formerly Enterobacter sakazakii) is a group of Gram-negative bacteria that exists in the environment and can survive in very dry conditions. The natural habitat for Cronobacter is not known.

Who is at risk of Cronobacter infection?

Cronobacter infections have been reported in all age groups. However, infants less than 2 months old are most likely to develop meningitis (an inflammation of the membranes that protect the brain and spine) if they are infected with Cronobacter bacteria. Infants born prematurely and those with weakened immune systems are also at risk for severe illness.

What kinds of illnesses does Cronobacter cause?

Cronobacter can cause several kinds of infections, and symptoms vary with the patient’s age and what part of the body is infected.

• Infants (<12 months old): In infants, Cronobacter can cause sepsis (a severe bloodstream infection) or meningitis (an infection of the protective membranes that surround the brain). Meningitis due to Cronobacter occurs almost exclusively among infants in the first 2 months of life. Infants with meningitis may develop seizures, brain abscesses or infarcts, hydrocephalus, or other serious complications that can cause long-term neurological problems. A recent report estimates that approximately 20% of infants with meningitis or bloodstream infections due to Cronobacter in the United States have died (Strysko, 2020). Worldwide, approximately 40% of infants reported to have Cronobacter meningitis or bloodstream infections have died (Strysko, 2020).
• People of all ages: Cronobacter can cause wound infections or urinary tract infections. People who have weakened immune systems due to illnesses or conditions, such as HIV, organ transplants, or cancer, and people who are 65 years and older are more likely to develop bloodstream infection due to Cronobacter. Cronobacter has also been found in the stool (poop) of people who have no symptoms, likely due to colonization. That means the bacteria is found in or on the body, but it does not cause any symptoms or disease. Cronobacter has also been found in the respiratory fluids of people on mechanical ventilators—but in this case, Cronobacter is likely to be colonizing the respiratory tract rather than causing illness.

How common is illness due to Cronobacter?

Cronobacter infection is rare. CDC typically receives reports of about 2 to 4 infections in infants per year, but Minnesota is the only state that requires reporting. Because most states do not require reporting, rates of Cronobacter infection in the United States are not well understood. However, a literature review from 1961 to 2018 provides evidence that Cronobacter infections are most common in infants less than 2 months old and often cause death in this age group. Also, infections among older adults may be more common, although milder, than infections among infants.

How many Cronobacter cases happen every year?

Unlike other foodborne illnesses, Cronobacter sakazakii infection is not a nationally notifiable condition and is not reportable in most states. This means that the true number of annual cases is unknown. Typically, CDC receives 2-4 reports of severe Cronobacter infections in infants annually from health departments and has received reports from 32 states. From January 2002 to July 2022, CDC received 76 reports of severe Cronobacter illnesses among infants. A recent report estimates that approximately 20% of infants with meningitis or bloodstream infections due to Cronobacter in the United States have died (Strysko, 2020). Worldwide, approximately 40% of infants reported to have Cronobacter meningitis or bloodstream infections have died (Strysko, 2020).

How is Cronobacter transmitted?

Cronobacter infections are often reported among infants who have been fed powdered infant formula. In some cases, Cronobacter has been found in powdered infant formula that was likely contaminated in the factory. In other cases, Cronobacter likely contaminated the powdered infant formula after it was opened at home or elsewhere. There have also been reports of infants getting sick after drinking pumped breast milk. In these cases, Cronobacter contaminated the breast pump parts.

Since Cronobacter bacteria live in the environment, there might be other ways babies can become infected. It is unknown if Cronobacter infection can be spread from one person to another, but other types of bacteria spread this way, especially in hospitals, if people do not wash their hands well.

How is Cronobacter infection diagnosed?

Cronobacter infection is diagnosed by a laboratory culture. Cronobacter can be detected in the blood or cerebrospinal fluid (CSF) of patients with sepsis or meningitis caused by these bacteria. Cronobacter bacteria grow on routine culture media, and microbiological laboratories can detect Cronobacter from blood or CSF samples.

If a Cronobacter infection is diagnosed by a laboratory culture in an infant, CDC encourages physicians, hospitals, and laboratories to inform their local or state health department.

How is Cronobacter infection managed?

Infants suspected of having Cronobacter sepsis or meningitis should undergo a full clinical evaluation for sepsis, including blood culture, urine culture, and cerebrospinal fluid culture. They should be hospitalized and given empiric antibiotics for sepsis immediately. Antimicrobial susceptibility testing for Cronobacter isolates should be performed because multidrug-resistant strains have been reported. Brain imaging studies of infants with meningitis can help detect brain abscesses and other complications. People with urinary tract infections or serious wound infections should also be treated with antibiotics. If a patient is colonized, rather than infected, with Cronobacter, treatment is not needed.

How does powdered infant formula become contaminated with Cronobacter?

Powdered infant formula is not sterile. Manufacturers report that, using current methods, it is not possible to produce sterile powdered infant formula. At the factory, Cronobacter could get into formula powder if:

• Contaminated ingredients are used to make the formula.
• The formula powder touches a contaminated surface.

In the home, you can accidentally get Cronobacter in powdered infant formula after the container is opened. For example, Cronobacter could get into the formula if:

• You place formula lids or scoops on contaminated surfaces, like countertops or sinks, and they later touch the formula.
• You mix the formula with contaminated water or in a contaminated bottle.

How can I prepare powdered infant formula with hot water if my baby is at higher risk?

In most cases, it is safe to mix powdered infant formula following manufacturer’s instructions on the container. But, if your baby is at higher risk, consider taking these extra steps to prepare your powdered formula with hot water (at least 158°F/70°C):

1. Wash hands with soap and water before preparing infant formula.
2. Clean work surfaces such as countertops and sinks with soap and water or use a disinfectant wipe or paper towel sprayed with cleaning product.
3. Boil water and let it cool for about 5 minutes.
4. Pour into a clean bottle or feeding cup.
5. Add the exact amount of formula listed on the container, put a cap on the bottle. Carefully shake the bottle instead of stirring the mixture.
6. If you plan to use the prepared formula right away, cool the formula to body temperature to ensure it is not too hot before feeding your baby. Run the prepared, capped bottle under cool water or place it in an ice bath. Do not let the cooling water get into the bottle or on the nipple.
7. Before feeding your baby, test the formula’s temperature by putting a few drops on the inside of your wrist. It should feel warm, not hot.

Use prepared infant formula within 1 hour from the start of feeding and within 2 hours of preparing it. If your baby does not finish the entire bottle of formula, throw away leftover formula.

If you do not plan to start feeding your baby with the prepared formula right away, put it in the refrigerator immediately. Use formula in the refrigerator within 24 hours. Throw out formula if you can’t remember how long you have kept it in the refrigerator. Do not feed it to your baby.

What is the best way to clean, sanitize, and store infant feeding items?

Help prevent Cronobacter from growing on these items and keep your baby’s milk safe by carefully cleaning, sanitizing, and storing bottles and breast pump parts.

• Clean surfaces like countertops and sinks with soap and water, or use a disinfectant wipe or paper towel sprayed with cleaning product.
• Clean and sanitize infant feeding items (such as nipples, caps, rings, and valves) and breast pump parts in a dishwasher or a clean wash basin that you use only for washing these supplies.
  • Take apart bottles and breast pump equipment after use for thorough cleaning.
  • Do not place these items directly in the sink because germs in sinks or drains could contaminate these items.
  • Allow items to air-dry thoroughly and store them in a clean, protected area.
• Keep powdered formula in the container dry to prevent germs from growing.
  • Avoid getting the formula scoop wet. There is no need to wash the scoop unless it becomes wet or dirty (such as falling on the floor). If the scoop needs to be washed, clean it as carefully as you would your baby’s bottles.
  • The formula scoop must be completely dry before putting it back into the container.

Cronobacter is a type of bacteria that can live in very dry places. Cronobacter has been found in dry foods, like powdered infant formula, powdered milk, herbal teas, and starches. It has also been found in water. Since Cronobacter bacteria live in the environment, there might be different ways babies can become infected.

Powdered formula is not sterile and might have bacteria in it.

Contaminated powdered infant formula from opened containers is the most common way that Cronobacter can spread to babies. Powdered infant formula can be contaminated with Cronobacter in homes or in processing facilities that make it.

At a processing facility, Cronobacter bacteria can get into powdered infant formula if:

• The manufacturer uses contaminated ingredients to make the formula.
• The formula powder touches a contaminated surface.

Manufacturers report that, using current methods, it is not possible to eliminate all germs from powdered infant formula in the factory.

In the home,Cronobacter can live on surfaces, such as a kitchen counter or sink, and in water.

Powdered infant formula can become contaminated with Cronobacter:

• After opening the container.
• If formula lids or scoops are placed on contaminated surfaces and then touch the formula.
• If the formula is mixed with contaminated water or in a contaminated bottle.

Infants have also become sick from Cronobacter bacteria grown on breast pump parts that were not cleaned properly.

It is unknown if Cronobacter infection can be spread from one person to another, but other types of bacteria spread this way, especially in hospitals, if people do not wash their hands well.

Cronobacter infections are rare, but most diagnosed Cronobacter infections are among infants who have been fed powdered infant formula. Infants who are more likely to get sick include:

• Infants less than 2 months old. These infants are most likely to develop meningitis if they get sick from Cronobacter.
• Infants born prematurely.
• Infants with weakened immune systems. Babies with certain medical conditions can’t fight bacteria as well because of their illness or medical treatment, such as chemotherapy for cancer.

Cronobacter infection can also be serious for:

• People 65 years and older.
• People whose immune systems are weakened by illnesses or conditions, such as HIV, organ transplants, or cancer.

Cronobacter infections are rare, but when infections happen, they can be deadly for young infants. Cronobacer infections usually occur in the first days or weeks of life. Typically, CDC receives reports of about 2­ to 4 cases of Cronobacter illness in infants each year. But in most states, doctors are not required to report cases to their health department. Cronobacter bacteria can cause severe bloodstream infections (sepsis) or meningitis (an inflammation of the membranes that protect the brain and spine).

Who is most at risk?

Infants who are more likely to get sick include:

• Infants less than 2 months old. These infants are most likely to develop meningitis if they get sick from Cronobacter.
• Infants born prematurely.
• Infants with weakened immune systems. Babies with certain medical conditions can’t fight germs as well because of their illness or medical treatment, such as chemotherapy for cancer.

Cronobacter infection can also be serious for:

• People 65 years and older.
• People whose immune systems are weakened by illnesses or conditions, such as HIV, organ transplants, or cancer.

Sicknesses from Cronobacter may look different depending on the person.

What are the symptoms?

Infants (less than 1 year old)

• Sickness from Cronobacter in infants will usually start with a fever and poor feeding, excessive crying, or very low energy. Some babies may also have seizures. Babies with these symptoms should be taken to a medical provider as soon as possible.
• In infants, especially those less than 2 months old, Cronobacter bacteria can get in the blood or make the lining surrounding the brain and spine swell (meningitis).
• Babies with meningitis may develop serious, long-lasting problems in their brains. A recent report estimates that approximately 20% of infants with meningitis or bloodstream infections due to Cronobacter in the United States have died (Strysko, 2020). Worldwide, approximately 40% of infants reported to have Cronobacter meningitis or bloodstream infections have died (Strysko, 2020).

People of all ages

• Cronobacter can cause problems in cuts, scrapes, or places where people have had surgeries.
• Cronobacter can also get into the urinary tract.
• People 65 years and older and people with weakened immune systems due to illness or conditions are more likely to get Cronobacter in their blood. People with weakened immune systems include those being treated with immune-suppressing drugs for cancer, other illnesses, or organ transplants, or those with HIV infection or genetic conditions.

Cronobacter infection is diagnosed by a laboratory culture.

Cronobacter can be detected in the blood or cerebrospinal fluid (CSF) of patients with meningitis or sepsis caused by Cronobacter bacteria. Cronobacter bacteria grow on routine culture media and microbiological laboratories can detect Cronobacter from blood or CSF samples.

CDC does not recommend testing stool for Cronobacter. Cronobacter infection does not typically cause diarrhea in infants.

If a Cronobacter infection is diagnosed in an infant by a laboratory culture, CDC encourages clinicians and laboratories to inform their local or state health department.

Brain imaging studies of infants with meningitis can help detect brain abscesses and other complications.

CDC does not recommend testing formula for Cronobacter contamination unless an infant has a diagnosed Cronobacter infection. In these situations, clinicians should communicate with their local or state health department to arrange testing.

Cronobacter infections are treated with antibiotics. Infants suspected of having sepsis or meningitis should be hospitalized and given empiric antibiotics immediately. Once Cronobacter has been diagnosed, antimicrobial susceptibility testing should be performed because multidrug-resistant strains have been reported. This testing can help medical providers choose the best antibiotic.

People with urinary tract infections or serious wound infections should also be treated with antibiotics.

If a patient is colonized, rather than infected, with Cronobacter, treatment is not needed.

Follow These Five Guidelines to Protect Your Baby From Cronobacter

You may want to take extra precautions if your baby is younger than 2 months old, was born prematurely, or has a weakened immune system:

1. Breastfeed if you can. Breastfeeding is one of the best things you can do for your baby’s health and development. Health officials and medical providers report very few cases of Cronobacter infection in infants fed only breast milk.

2. Clean, sanitize, and store feeding items such as baby bottles and breast pump parts safely. Help prevent germs from growing on these items and keep your baby’s milk safe. You can do this by carefully cleaning, sanitizing, and storing bottles and breast pump parts. Take apart bottles and breast pump equipment after use for thorough cleaning.

3. Keep hands clean! Always wash your hands with soap and water for at least 20 seconds during key times:

• Before preparing and feeding bottles or food to your baby
• Before touching your baby’s mouth
• Before touching pacifiers or other things that go into your baby’s mouth
• After using the toilet or changing diapers

If soap and water are not available, use a hand sanitizer with at least 60% alcohol. Check the product label to be sure. Wash hands with soap and water as soon as possible after using hand sanitizer. Hand sanitizer with at least 60% alcohol kills Cronobacter. But hand sanitizer does not kill all types of germs. It may not work as well if hands are visibly greasy or dirty.

4. If you feed your baby with formula, consider using liquid formula when possible. Powdered infant formula is not sterile and might have germs in it. Using a liquid formula instead of powdered is especially important if your baby:

• Is less than 2 months old
• Was born prematurely, or
• Has a weakened immune system.

Liquid infant formula is made to be sterile (without germs). This means liquid formula should not make your baby sick with Cronobacter infection when you follow the instructions on the container.

You do not need to warm infant formula before feeding, but some people like to warm their baby’s bottle. If you do warm the bottle, never use a microwave. Microwaves heat milk and food unevenly, resulting in “hot spots” that can burn your baby’s mouth and throat.

• To warm a bottle, place it under warm running water. Keep the running water from getting into the bottle or on the nipple. Put a couple drops of infant formula on the inside of your wrist to make sure it is not too hot.

5. Prepare and store powdered infant formula safely. Make sure that your formula is not expired or recalled. The container should be in good condition with no dents, puffy ends, or rust spots. Keep powdered formula lids and scoops clean. Close containers of formula as soon as possible.

In most cases, it is safe to mix powdered infant formula following manufacturer’s instructions on the container. But, if your baby may be at higher risk, consider taking these extra steps to prepare your powdered formula with hot water (at least 158°F/70°C):

1. Clean work surfaces, such as countertops and sinks, with soap and water, or use a disinfectant wipe or paper towel sprayed with cleaning product. Do not place feeding items directly in the sink, because germs in sinks or drains could contaminate these items.
2. Wash hands with soap and water before preparing infant formula.
3. Boil water and let it cool for about 5 minutes.
4. Pour the water into a clean bottle or feeding cup.
5. Add the exact amount of formula listed on the container.
6. Carefully shake the capped bottle rather than stirring the mixture.
7. If you plan to use the prepared formula right away, cool the formula to body temperature to ensure it is not too hot before feeding your baby. Run the prepared, capped bottle under cool water or place it into an ice bath. Do not let the cooling water get into the bottle or on the nipple.
8. Before feeding the baby, test the formula’s temperature by putting a few drops on the inside of your wrist. It should feel warm, not hot.

Use prepared infant formula within 1 hour from start of feeding and within 2 hours of preparing it. If your baby does not finish the entire bottle of formula, throw away leftover formula.

If you do not plan to start feeding your baby with the prepared formula right away, put it in the refrigerator immediately. Use formula in the refrigerator within 24 hours. Throw out formula if you can’t remember how long you have kept it in the refrigerator. Do not feed it to your baby.