Carbapenem-Resistant Organisms (CRO)


What are carbapenems?

Carbapenems are a class of broad-spectrum antibiotics reserved to treat serious multidrug-resistant infections. Carbapenems are often considered antibiotics of last resort to treat an infection. This antibiotic class includes the following generic names: doripenem, ertapenem, imipenem, and meropenem.

Which organisms can become carbapenem-resistant?

All organisms have the potential to become resistant to carbapenems. Organisms of greatest concern include the Enterobacteriaceae family. Common organisms in this family include E. coli and Klebsiella species. Other organisms that can become resistant to carbapenems that are highly concerning include Acinetobacter and Pseudomonas species.

Why should I be concerned about carbapenem-resistant organisms (CROs)?

Infections that are resistant to these antibiotics are very difficult to treat. CDC considers these types of antibiotic-resistant infections an urgent threat in the United States. CROs may cause a variety of infections, ranging from gastrointestinal illness and pneumonia to invasive infections of the bloodstream or organs.

What are the risk factors for getting an infection caused by a CRO?

Healthy people usually do not get CRO infections. Patients who require devices like ventilators (breathing machines), urinary (bladder) catheters, or intravenous (vein) catheters; patients who are taking long courses of certain antibiotics, patients who are immunocompromised; and patients who have received international healthcare are most at risk for CRO infections.

How are CRO infections transmitted?

CRO is spread through contact with infected or colonized people, particularly contact with wounds, stool or contaminated hands or devices.


Infection Prevention

Decreasing antimicrobial resistant infections, such as carbapenem-resistant organisms (CROs) and carbapenemase-producing organisms (CPOs), require antimicrobial stewardship efforts and infection prevention measures.  Intensity of infection prevention measures is based on mechanism of carbapenem resistance (CPO vs non-CPO), patient’s clinical status, and factors that increase risk of transmission to other patients in the facility. VDH recommends following the below guidance documents.


Public Health Response: Virginia Containment Strategy for Carbapenemase-Producing Organisms

Reporting Requirements


The State Board of Health updated the Virginia Regulations for Disease Reporting and Control (12 VAC 5-90-80) effective November 14, 2018. Carbapenemase-producing organisms (CPOs) were added to the reportable disease list and conditions reportable by directors of laboratories. Thus, the responsibility for reporting the presence of these organisms rests with physicians, directors of medical care facilities, and directors of laboratories.  Because of the special laboratory testing needed to identify and confirm these organisms, however, it is expected that laboratories will be the primary responsible party for reporting these organisms.  A further complexity exists because of the differing levels of capacity for identifying and/or confirming the presence of these organisms in laboratories.  The guidance below is intended to clarify requirements for reporting and for submitting isolates for further public health testing.


Carbapenemase Producing Organisms (CPO) are defined as organisms where the isolate is:

  • Positive for carbapenemase production by a phenotypic method (e.g., mCIM, Carba NP)
  • Positive for a known carbapenemase resistance mechanism by a recognized test (e.g., PCR, X-pert CarbaR)


Public Health Response

Upon confirmation of CP-CRE or CP-CRPA, the local health department will work with the facility/provider to implement the CDC Containment Strategy for Novel or Targeted Multidrug-resistant Organisms by:

  1. Identifying transmission is occurring;
  2. Identifying affected patients, such as roommates and high risk healthcare contacts;
  3. Ensuring appropriate control measures are promptly initiated/implemented to contain potential spread; and
  4. Characterizing the organism or resistance mechanism in order to guide additional response actions, patient management, and future responses.

For more information, please see the VDH HAI High Sign Special Edition on Carbapenemase-Producing Organisms

Contact the HAI/AR Program for questions or discussion.

Last Reviewed:  November 2019.  VDH will review this interpretive guidance annually at a minimum, and as needed due to regulation changes.

Impact in Virginia

Infections caused by carbapenemase-producing organisms (CPOs) have been identified in all Virginia regions.

Virginia CPO Case Counts

Click here for our quarterly CPO report.

National Testing Data

CDC Antibiotic Resistance and Safety Patient Portal

Emergency Department Care Coordination System

The Emergency Department Care Coordination (EDCC) Program was established in 2017 to provide a statewide technology solution that connects healthcare facilities, including acute care hospitals and post-acute care facilities. EDCC now includes MDRO flags for Candida auris and Carbapenemase-producing Organisms (CPOs), but facilities should still communicate MDRO status on transfer as the alerts are not real-time and only include information for Virginia patients and residents known to VDH. The flags are not intended to replace recommended communication, but to provide an additional layer of information.


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