Carbapenem-resistant Enterobacteriaceae are a family of germs that are difficult to treat because they have high levels of resistance to antibiotics. Klebsiella species and Escherichia coli (E. coli) are examples of Enterobacteriaceae, a normal part of the human gut bacteria, that can become carbapenem-resistant.

In healthcare settings, CRE infections most commonly occur among patients who are receiving treatment for other conditions. Patients whose care requires devices like ventilators (breathing machines), urinary (bladder) catheters, or intravenous (vein) catheters, and patients who are taking long courses of certain antibiotics are most at risk for CRE infections.

General information about CRE

CRE stands for carbapenem-resistant Enterobacterales. Enterobacterales are an order of germs, specifically bacteria. Many different types of Enterobacterales can develop resistance, including Klebsiella pneumoniae and Escherichia coli (E. coli). These bacteria can cause infections including pneumonia, bloodstream infections, urinary tract infections, wound infections, and meningitis.

CRE are a major concern for patients in healthcare settings because they are resistant to carbapenem antibiotics, which are considered the last line of defense to treat multidrug-resistant bacterial infections. Often, high levels of antibiotic resistance in CRE leave only treatment options that are more toxic and less effective.

How common are CRE infections?

In 2017, CRE caused an estimated 13,100 infections in hospitalized patients, and 1,100 estimated deaths in the United States.

Who is most likely to get a CRE infection?

Healthy people usually do not get CRE infections—they are most common in patients in hospitals and long-term care facilities like skilled nursing facilities and long-term acute care hospitals. Patients whose care requires devices like ventilators (breathing machines), urinary (bladder) catheters, or intravenous (vein) catheters, patients who are taking long courses of certain antibiotics, and patients with weakened immune systems are among those at risk for CRE infections.

What is the difference between colonization and infection?

Some people have germs on or in their body, but those germs do not cause an infection. These people are said to be colonized.

People colonized with CRE can develop infections, but most will not. CRE can cause infections when the germs enter the body, often through medical devices like ventilators, intravenous catheters, urinary catheters, or wounds caused by injury or surgery.

How are CRE germs spread?

CRE are usually spread person to person through contact with infected or colonized people, particularly contact with wounds or stool (poop). This contact can occur via the hands of healthcare workers, or through medical equipment and devices that have not been correctly cleaned.

How can I protect myself from CRE?

As a patient, there are several ways you can protect yourself.

• Tell your healthcare provider if you have been hospitalized in another healthcare facility, including hospitals in other countries.
• Make sure all healthcare providers clean their hands before caring for you. If you don’t see your providers clean their hands, ask them to do so.
• Clean your own hands often, and ask anyone taking care of you to clean their hands:

  Clean Hands Count

  • Before preparing or eating food
  • Before touching your eyes, nose, or mouth
  • Before and after changing wound dressings or bandages
  • Before handling medical devices or touching tubes going into your body
  • After using the bathroom
  • After blowing nose, coughing, or sneezing

Be Informed about Antibiotic Resistance

• If you are prescribed antibiotics, take them exactly as your healthcare provider recommends.
• Talk to your healthcare provider about your care and any concerns you have. Ask them what they are doing to protect you from getting an infection while receiving care.
• Avoid preventable infections by making sure you are up to date on all recommended vaccinations.

How are CRE infections treated?

Treatment decisions for patients with CRE infections are made on a case-by-case basis by a healthcare provider. For patients who are colonized with CRE but do not have an infection, treatment is often not required.

What if I have CRE?

Follow your healthcare provider’s instructions. If your provider prescribes antibiotics, take them exactly as instructed and finish the full course, even if you feel better. Clean your hands often, especially after you have contact with the infected area, after using the bathroom, and before preparing or eating food. Follow any other hygiene advice your provider gives you. Be alert to changes in your health (e.g., if you develop diarrhea), and contact your healthcare provider if changes occur.

Clinicians play a critical role in helping to identify patients colonized or infected with CRE and preventing its spread.

What are CRE?

CRE stands for carbapenem-resistant Enterobacterales. Enterobacterales are an order of bacteria commonly found in people’s gastrointestinal tract that can cause infections both in healthcare and community settings.

All CRE are likely multidrug-resistant organisms and interventions might be required in healthcare settings to prevent transmission. However, a subset of CRE, called carbapenemase-producing CRE (CP-CRE), are currently believed to be primarily responsible for the increasing spread of CRE in the United States and have therefore been targeted for aggressive prevention.

What is the CDC CRE definition?

Enterobacterales that test resistant to at least one of the carbapenem antibiotics or produce a carbapenemase (an enzyme that can make them resistant to carbapenem antibiotics) are called CRE. Some Enterobacterales (e.g., Proteus spp., Morganella spp., Providencia spp.) have intrinsic elevated minimum inhibitory concentrations (MICs) to imipenem and therefore results for meropenem, doripenem, and ertapenem should be used for these organisms to determine if they meet the CRE definition.

In the United States, CRE are generally associated with healthcare settings, and approximately 30% of CRE carry a carbapenemase. These carbapenemase genes are often on mobile genetic elements, which can be easily shared between bacteria, leading to the rapid spread of resistance.

Why are CP-CRE considered epidemiologically important?

• CRE organisms are often resistant to multiple classes of antibiotics, substantially limiting treatment options.
• Infections caused by these organisms are associated with high mortality rates among hospitalized patients, up to 50% in some studies.
• Many CRE produce carbapenemases, which can be transmitted from Enterobacterales to other germs, facilitating spread of resistance.
• Enterobacterales are a common cause of infections in both community and healthcare settings. Although CRE is currently primarily associated with inpatient healthcare settings, it has the potential to spread to community settings.

For these reasons, CDC has developed resources to support healthcare providers as they screen patients for CRE and take action to decrease transmission of CRE.

What is the difference between CRE colonization and infection?

When found in clinical culture, CRE can represent an infection or colonization. Colonization means that the organism can be found in or on the body but it is not causing any symptoms or disease. Colonizing CRE strains can go on to cause infections or spread to other patients. Colonization screening is a CDC-recommended intervention that can help stop the spread of CRE. The AR Lab Network offers free colonization screening.

Which patients are at increased risk for CRE acquisition?

The main risk factors for CRE acquisition in the United States include exposure to healthcare and exposure to antibiotics. Healthcare-related risk factors include requiring help with most activities of daily living, like toileting and bathing, exposure to an intensive care unit, and mechanical ventilation. Several antibiotics have been associated with getting CRE, including carbapenems, cephalosporins, fluoroquinolones, and vancomycin.

How are CRE transmitted?

In healthcare settings, CRE are transmitted from person to person, often via the hands of healthcare personnel or through contaminated medical equipment. Additionally, sink drains and toilets are increasingly recognized as an environmental reservoir and CRE transmission source.

What infections do CRE cause?

CRE can cause infections in almost any body part, including bloodstream infections, ventilator-associated pneumonia, and intra-abdominal abscesses. Based on information from a CDC pilot surveillance system, most CRE infections involve the urinary tract, often in people who have a urinary catheter or have urinary retention.

What can clinicians do to prevent CRE transmission?

• Know if patients with CRE are admitted to your facility and stay aware of CRE infection rates in your facility.
• When you transfer a patient with CRE, use an inter-facility transfer form to alert the receiving facility during the transition of care.
• Ask if a patient has received medical care somewhere else, including another facility or other countries.
• Screen patients who have had an overnight stay in a healthcare facility outside the United States in the prior 6 months for the presence of carbapenemase-producing CRE. Free admission screening is available through the AR Lab Network. Contact your HAI coordinator for more information on accessing AR Lab Network testing.
• Whenever possible, place patients currently or previously colonized or infected with CRE in a private room with a bathroom and dedicate noncritical equipment (e.g., stethoscope, blood pressure cuff) to CRE patients.
• Wear a gown and gloves when caring for patients with CRE.
• Perform hand hygiene—use alcohol-based hand rub or wash hands with soap and water before and after contact with patient or their environment.
• Make sure labs immediately alert clinical and infection prevention staff when CRE are identified. If your laboratory does not perform testing for carbapenemases, talk to your HAI coordinator about getting isolates tested through the AR Laboratory Network.
• Prescribe and use antibiotics appropriately.
• Discontinue devices like urinary catheters as soon as no longer necessary.
• When a patient with an unusual type of carbapenemase-producing CRE is identified in your facility, work with public health to prevent spread, including following guidance to assess for ongoing transmission.

When can Contact Precautions be discontinued for patients colonized or infected with CRE?

There is currently not enough information for CDC to make a general recommendation on when isolation can be discontinued for patients colonized or infected with CRE. CRE colonization can be prolonged (> 6 months). Across multiple studies, predictors of prolonged CRE carriage have been found to include:

• exposure to antibiotics
• presence of an invasive device
• higher Charlson’s co-morbidity scores
• number of hospital admissions
• admission from another facility
• admission from or discharge to a long-term care facility [Schechner et al., 2011; Feldman et al., 2013; Zimmerman et al., 2013]

Presence of these predictors should be considered when deciding whether to discontinue Contact Precautions.

If considering discontinuing Contact Precautions based on the results of surveillance cultures, it is appropriate to wait for at least 3 to 6 months since last positive culture or screen. The decision to discontinue Contact Precautions for an individual with a history of colonization or infection with CRE should be made in consultation with public health. In general, failure to identify CRE from at least two sets of screening cultures are the minimum criteria that should be met before an episode of colonization is considered resolved. Additionally, retesting of the site(s) that were positive initially from clinical cultures is usually indicated, particularly non-sterile sites such as a wound or urine.

Carbapenem-resistant Enterobacterales (CRE) are a serious threat to public health. Infections with CRE are difficult to treat and have been associated with mortality rates of up to 50% for hospitalized patients. Due to the movement of patients throughout the healthcare system, if CRE are a problem in one facility, then typically they are a problem in other facilities in the region as well.

Healthcare facilities should:

• Recognize these organisms as important to patient safety and adhere to public health guidance for CRE detection, tracking, and reporting.
• Ensure their clinical laboratory can accurately identify CRE and has a policy to immediately alert clinical and infection prevention staff when CRE are identified.
• Understand the local epidemiology of carbapenemase-producing CRE, including prevalence in the facility and in the region. If your laboratory does not perform testing for carbapenemases, talk to your HAI coordinator about getting isolates tested through the AR Laboratory Network.
• Ensure precautions are implemented for CRE colonized or infected patients. These include:
  • Whenever possible, place acute care patients currently or previously colonized or infected with CRE in a private room with a bathroom and dedicate noncritical equipment (e.g., stethoscope, blood pressure cuff) to CRE patients.
  • Have and enforce a policy for using gown and gloves when caring for patients with CRE.
  • Have and enforce policies for healthcare personnel hand hygiene before and after contact with patient or their environment, and increase emphasis on hand hygiene on a unit caring for a patient or resident with CRE.
• Healthcare personnel should follow standard hand hygiene practices, which include use of alcohol-based hand sanitizer or, if hands are visibly soiled, washing with soap and water.
• When a patient with an unusual type of carbapenemase-producing CRE is identified in your facility, work with public health to prevent spread, including following guidance to assess for ongoing transmission.
• Have a system to assess, at admission, if a patient has received medical care somewhere else, including other facilities or other countries. Screen patients who have had an overnight stay in a healthcare facility outside the United States in the prior 6 months for the presence of carbapenemase-producing CRE. Admission screening is available free of charge through the AR Lab Network. Contact your HAI coordinator for more information on accessing AR Lab Network testing.

Transfer a Patient with CRE

• When transferring a patient or resident, require staff to notify the receiving facility about infection or colonization with CRE and other multidrug-resistant organisms.
• Support healthcare providers prescribing and using antibiotics appropriately.
• Participate in regional and facility-based prevention efforts designed to stop the transmission of these organisms.

Antibiotic-resistant germs have developed the ability to resist the effects of antibiotics designed to kill them. If your pet has an antibiotic-resistant infection, your veterinarian might ask to do additional tests to be sure they choose the correct drug to treat the infection. Antibiotic-resistant infections may take longer to treat and can be more expensive to treat. Talk to your veterinarian about what to expect and how to prevent your pet’s germs from spreading to other pets and people in your home.

What is CRE and why are some CRE a public health concern?

CRE is a type of antibiotic-resistant germ and is an urgent public health threat. CRE stands for carbapenem-resistant Enterobacterales. Enterobacterales are a group of bacteria (a type of germ) commonly found in the digestive systems of people and animals. Both people and animals can carry CRE in their gut without getting sick. But if these germs get into other parts of the body, they can cause serious infections of the lungs, blood, urinary tract, and brain.

Carbapenems are antibiotics used to treat serious multidrug-resistant bacterial infections. Carbapenem-resistant Enterobacterales (CRE) can survive carbapenem antibiotic treatment, making the infections they cause very difficult to treat. Antibiotics used to treat CRE can have more side effects and be less effective than treatments for less antibiotic-resistant germs.

Does everyone with CRE get sick?

No. Both humans and animals can be colonized with CRE, meaning they can carry the bacteria in their gut without it causing infection. People and animals colonized with CRE may still shed the germ into their environment and can still spread the germ to others.

How did my pet get this germ?

Animals can get CRE from many potential sources, including contaminated food or contact with people or animals who are infected with or carriers of the germ. Because people and animals can carry CRE in their gut without any symptoms, it might be hard to know exactly where your pet got CRE.

Can I/my family get this germ from our pet?

Pets and people can share germs, including CRE. We don’t know how often this happens with CRE. There are only a few reports describing exchange of CRE between animals and people, but it is difficult to find the direction of spread (from person to animal or from animal to person).

Scientists are working to better understand the risk to owners of developing a CRE infection from exposure to a pet, but generally the risk is thought to be low. Healthy people rarely get CRE infections. The people who are most at risk of getting this germ are those who have weakened immune systems, have recently taken antibiotics, or who need medical devices like ventilators (breathing machines) or urinary catheters.

How can pet owners reduce the risk of getting antibiotic-resistant germs like CRE from their pets?

A few simple precautions can reduce the risk of getting CRE and other germs after contact with animals:

Clean Your Hands

Whether you are playing with, feeding, or cleaning up after your pet, it is important to clean your hands to help reduce the risk of getting sick from the germs pets can carry. If you or a family member are concerned about illness, talk to a doctor and mention the animals you’ve had contact with recently.

Always clean hands:

• After touching or playing with your pet
• After feeding your pet or handling pet food
• After providing medical or nursing care
• After handling pet habitats or equipment (crates, cages, toys, food and water dishes, etc.)
• After cleaning up after pets
• Before preparing food or drinks
• Before eating and drinking
• After removing soiled clothes or shoes

You can use either an alcohol-based hand sanitizer or soap and running water to clean your hands. If hands are visibly soiled, then soap and water should be used. Adults should help young children with hand washing.

Practice Good Pet Hygiene

In addition to hand washing, practicing good pet hygiene can help prevent the spread of germs between pets and people. Keep pets and their supplies out of the kitchen and disinfect pet crates/carriers and supplies outside the house when possible. Whenever possible, avoid cleaning pet supplies in the kitchen sink, food preparation areas, or the bathroom sink. Pets can contaminate surfaces in your home with germs—you don’t have touch pets to get sick from their germs.

Always remove your dog’s feces (poop) from your yard and public places using a bag, dispose of it in proper areas, and clean your hands after. Dog and cat poop can contain germs and parasites that can be harmful to people. Keep children away from areas that might contain dog or cat poop.

If your pet is sick, call your veterinarian. Cats or dogs that have diarrhea should be seen by a veterinarian. If your pet has a history of CRE, tell the veterinary clinic/hospital staff when you book an appointment and at the time of arrival about your pet’s history of this germ.

You can find more information about reducing the risk of spreading germs from pets to you and your family at Healthy Pets Healthy People.

Can other animals in our house get this germ?

CRE can spread between animals, so owners of a pet with CRE should discuss the risk to their other animals with their veterinarian. To avoid the spread of the germ between animals in the household:

• Practice good personal hygiene, especially hand washing after handling pets/pet food or cleaning litter boxes/cleaning up poop.
• Keep litter boxes, pet dishes, pet beds, and toys clean. Litter boxes should be cleaned at least daily.
• Keep pets away from wildlife.

Should I give up my pet if he/she gets CRE?

No, it is not necessary to give up a pet with CRE. You should take steps to reduce your risk of getting CRE from your pet, like cleaning your hands often and practicing good pet hygiene.

If you have a higher risk of infection (for example, you have a weakened immune system, you take antibiotics frequently, or you use medical devices like urinary catheters), then you should also follow these helpful tips to reduce your risk of getting CRE from your shared environment:

• Avoid changing cat litter, cleaning up your pet’s poop, or bathing your pet, if possible. If no one else can perform the task, then wear disposable gloves and wash your hands with soap and water afterwards.
• Avoid letting your pet lick/kiss your face and any wounds you have.
• Keep outdoor sandboxes covered.
• Wear gloves when gardening and during contact with soil or sand because it might be contaminated with animal feces (poop). Wash hands with soap and water after gardening or contact with soil or sand.

If you’re concerned about your risk of CRE infection, talk to your healthcare provider.

How long will my pet carry CRE?

Not much is known about how long companion animals may carry CRE. A veterinary clinic found that among 12 dogs with CRE, most tested negative within 3 months of CRE first being identified, and all tested negative after 6 months. More data are needed to understand how long CRE can stay in a pet. Additionally, pets might carry CRE longer if they are continually exposed over time or if they receive antibiotic treatment. If your pet has a CRE infection, they may continue to carry the germ even after they have been treated and their symptoms disappear.

Do pets that test positive for CRE need to stay away from the dog park?

If your pet has CRE, they could spread it to other animals at the dog park. So, it is recommended that dogs do not visit the dog park if they are currently sick, have an active infection, or are taking antibiotics. Since animals may carry CRE for several months, even if they don’t have symptoms of infection, talk to your veterinarian about when your dog can go back to the dog park or be around other animals. Always remove your dog’s feces (poop) from your yard and public places using a bag, dispose of it in proper areas, and clean your hands.