Carbapenemase-producing Enterobacteriaceae* (CPE) infection or colonisation

Clinical criteria
Not relevant for surveillance purposes.

Laboratory criteria
The identification of carbapenemase-producing Enterobacteriaceae* (CPE) from any specimen, whether a diagnostic (invasive, non-invasive infection or colonisation, also known as carriage) or screening specimen (colonisation, also known as carriage).

CPE are Enterobacteriaceae* confirmed to have one or more specific families of gene that encode for production of a carbapenemase (e.g., OXA-48 like, KPC, NDM, VIM, IMP etc.).

Confirmation of the presence of a carbapenemase gene/enzyme should be by a reliable laboratory method, such as molecular or immunological methods.

Epidemiological criteria
Not relevant for surveillance purposes.

Case classification
- Possible case: Not applicable
- Probable case: Not applicable
- Confirmed case: Any person meeting the laboratory criteria

Outbreak
An outbreak of CPE is defined as two or more confirmed cases of the same carbapenemase (causing any of; invasive or non-invasive infection or colonisation) that are linked epidemiologically in time and place.

Note: Given that chains of CPE transmission are generally silent at the time of transmission and may involve multiple species of Enterobacteriaceae, assessment of linkage is challenging. Guidance on making this assessment is available at HCAI website. An outbreak control team should be convened to assess what action is required.

Definitions
Carbapenem: A group of antimicrobials used to treat infection due to antimicrobial resistant organisms, such as extended spectrum beta lactamase (ESBL)-producing or other multi-drug resistant (MDR) Enterobacteriaceae. Carbapenems include; meropenem, ertapenem and imipenem.

Carbapenemases: Enzymes produced by some Enterobacteriaceae and other bacteria, which can break down carbapenems, rendering them ineffective for treatment of infection. The genes that code for carbapenemase production can easily be transferred from one strain of bacteria to another in the human gut. Bacteria that produce carbapenemases can easily be spread from one person (or patient) to another in the absence of adequate precautions (e.g., good hand washing).

Enterobacteriaceae: This is a family of bacteria. Due to recent technical changes in bacterial classification the strict meaning of the term Enterobacteriaceae has been narrowed. The term Enterobacterales now encompasses the group of bacterial genera formerly considered to be Enterobacteriaceae. In practical terms, at present, the terms are often used as interchangeable. This group of bacteria are found in the gut of humans and animals, where they make up a large part of the normal bacterial flora. They are shed in very large numbers in faeces and can contaminate the environment. Occasionally, they can cause infection or disease. Enterobacteriaceae include (but are not restricted to) the following genera: Escherichia, Klebsiella, Citrobacter, Enterobacter, Serratia, Proteus, Morganella, Salmonella, Shigella.

Carbapenem resistance and carbapenemase production can also be problematic in non-Enterobacteriaceae including; Acinetobacter spp. and Pseudomonas spp. However, as these are not in the family Enterobacteriaceae they are not notifiable as CPE. Certain genera (e.g., Stenotrophomonas spp.) have an intrinsic property of carbapenemase production and are generally intrinsically resistant to carbapenems. These bacteria are not notifiable as CPE.

• Colonisation or carriage = Detection of CPE from a rectal swab or faeces or from a diagnostic specimen taken in the absence of evidence for active infection (e.g., midstream or catheter specimen of urine, swabs of wounds or chronic skin breaks, sputum etc.)
• Non-invasive infection = Detection of CPE from a diagnostic specimen taken in presence of evidence for active infection (e.g., urine, sputum, wound swabs etc.)
• Invasive infection = Detection of CPE from a diagnostic specimen from a normally sterile site (e.g., blood, cerebrospinal fluid (CSF), peritoneal fluid, pleural fluid etc.)

Note on colonisation/carriage: Because Enterobacteriaceae are normal residents of the human gut, once a person acquires CPE they are considered to be colonised indefinitely. However, there is evidence that some people cease to be CPE carriers in time. Under certain conditions, a person designated as CPE colonised may have that designation removed if CPE is not detectable for an extended period of time. However, it is very difficult to be confident that non-detection represents complete clearance.

*Enterobacteriaceae are also known as Enterobacterales

Current as of: 5 February 2019