CPE stands for Carbapenemase-Producing Enterobacterales, a group of bacteria that have developed resistance to carbapenems, the most powerful antibiotics available. These bacteria are sometimes called “superbugs” because they can shrug off drugs that are normally reserved as a last resort when other antibiotics fail. CPE infections are rare but serious, with a 30-day mortality rate of about 19% for infected patients and 30% for those who develop bloodstream infections.
How CPE Bacteria Resist Antibiotics
Your gut naturally contains bacteria from a family called Enterobacterales. Common members include E. coli and Klebsiella pneumoniae. Most of the time these bacteria are harmless, but they can cause infections in the urinary tract, lungs, blood, or surgical wounds. When they do, doctors treat them with antibiotics.
CPE bacteria produce a specific enzyme called carbapenemase. This enzyme breaks apart carbapenem antibiotics at the molecular level, disabling them before they can kill the bacteria. What makes this especially dangerous is that the genetic instructions for producing this enzyme sit on small, mobile pieces of DNA called plasmids. Bacteria can pass these plasmids to entirely different species of bacteria, spreading resistance through a hospital like a shared blueprint.
CPE vs. CRE: What’s the Difference
You’ll often see the term CRE (Carbapenem-Resistant Enterobacterales) used alongside CPE, and the two overlap but aren’t identical. CRE is the broader category: any Enterobacterales bacteria resistant to at least one carbapenem antibiotic. CPE is a specific subset of CRE where that resistance comes from producing the carbapenemase enzyme. Other CRE bacteria achieve resistance through different mechanisms, like blocking the antibiotic from entering the cell or pumping it back out. The distinction matters clinically because the type of resistance determines which treatments still work.
Who Is Most at Risk
CPE is overwhelmingly a healthcare-associated problem. Among patients found to carry CPE, over 80% had been hospitalized within the previous three months. The strongest risk factor is time spent in an intensive care unit, which increases the odds of picking up CPE dramatically. Other significant risk factors include having catheters, feeding tubes, or other invasive devices in place, open wounds, recent antibiotic use, and admission to a nursing home.
Patients who have been hospitalized or had an invasive medical procedure in another country within the past six months are also considered higher risk, since CPE prevalence varies significantly around the world. The CDC recommends screening these patients on arrival.
Colonization vs. Active Infection
Being “colonized” with CPE means the bacteria are living in your body, usually in the gut, without causing any symptoms. You can carry CPE and feel perfectly fine. Colonization is far more common than actual infection, and hospitals screen for it using rectal swabs specifically because carriers can unknowingly spread the bacteria to other patients.
The concern is that colonization sets the stage for infection. Studies estimate that roughly 12% to 23% of people colonized with CPE go on to develop a clinical infection, most commonly a urinary tract infection. The jump from harmless carriage to dangerous infection typically happens when a patient’s immune system is already weakened or when the bacteria reach a normally sterile part of the body during surgery or through a catheter.
How CPE Is Detected
Hospitals use two main approaches to identify CPE. The first is culture-based: a sample (often a rectal swab) is placed on specialized agar plates designed to only grow bacteria resistant to carbapenems. If colonies appear, further testing determines whether the bacteria are actually producing the carbapenemase enzyme, using disc-based tests with different enzyme inhibitors.
The second approach is molecular testing, which is faster. PCR-based tests can detect the genes responsible for carbapenemase production directly from a rectal swab, identifying the specific type of enzyme involved. Some rapid tests can simultaneously screen for the four most common carbapenemase types in a single run. Speed matters here because every hour a carrier goes unidentified is an hour they could spread the bacteria to other vulnerable patients.
Treatment Challenges
Treating a CPE infection is difficult precisely because the bacteria have neutralized the strongest antibiotics in the standard toolkit. Treatment depends on which type of carbapenemase enzyme the bacteria produce, because different enzymes have different vulnerabilities. Doctors identify the enzyme type through lab testing, then select from a small number of newer antibiotic combinations that pair a carbapenem or related drug with a compound that blocks the enzyme.
For the most common enzyme type (called KPC), several combination antibiotics remain effective. For other enzyme types, options narrow considerably, sometimes requiring two different IV antibiotics administered simultaneously. These treatments are given in hospital settings and reserved specifically for confirmed resistant infections to avoid fueling even further resistance.
How Hospitals Prevent CPE Spread
Because CPE spreads primarily through direct contact in healthcare settings, infection control is the front line of defense. Patients identified as CPE carriers are placed in isolation with contact precautions, meaning healthcare workers wear gowns and gloves for every interaction. In nursing homes, the approach may be adapted to “enhanced barrier precautions” depending on the situation.
Environmental cleaning is critical because CPE can survive on surfaces. Hospitals enforce strict hand hygiene protocols and may conduct periodic screening of high-risk patients, particularly in ICUs, to catch new carriers before an outbreak develops. The incidence of CPE infections in hospitals has been rising steadily. In Canadian acute care facilities tracked over more than a decade, the rate of healthcare-associated CPE infections more than quadrupled between 2015 and 2023, though it remains low overall at roughly 0.09 per 10,000 patient-days.
For the average person outside a hospital, CPE poses minimal risk. The bacteria primarily threaten people who are already seriously ill, immunocompromised, or undergoing invasive medical procedures. The public health concern is that if CPE continues to spread and share its resistance genes with other bacteria, the pool of treatable infections shrinks for everyone.