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Healthcare-associated infections (HAI) program

Carbapenem-resistant and Carbapenemase-producing Organisms for Public Health and Healthcare Providers


Carbapenem-resistant organisms (CRO) are Gram-negative bacteria that are resistant to the broad-spectrum, “last resort” carbapenem class of antibiotics. They include: bacteria from the Enterobacterales order (previously Enterobacteriaceae) (CRE), such as E. coli or Klebsiella pneumoniaePseudomonas aeruginosa (CRPA); and Acinetobacter baumannii (CRAB). Patients with CRO infections have significantly worse outcomes than patients with susceptible infections. Certain CRO are resistant because they produce carbapenemase enzymes (e.g., KPC, NDM, OXA, VIM, IMP) that make carbapenems ineffective. Carbapenemase genes can be transferred between different kinds of bacteria and lead to the spread of antibiotic resistance.

Carbapenemase-producing organisms (CPO) are increasingly more common throughout California healthcare settings. Public health and healthcare providers across the continuum of care are coordinating efforts to prevent the emergence and transmission of CRO, CPO and other highly drug-resistant infections in California. 

Key Documents:

Carbapenemase-producing Organisms: ​CDPH Laboratory and Epidemiology Updates. May 14, 2024
Best Practices for SNFs in Accepting Residents with MDROs.  February 15, 2024
The Role of Carbapenemase Testing in Clinical Practice.  December 6, 2022
Testing for Carbapenemase Production Among Carbapenem-Resistant Organisms: When and How? October 27, 2022
Carbapenemase-producing Organisms: Guidance for Reporting and Containment. September 29, 2022
Antimicrobial Resistance Testing: Public Health Laboratory Testing Updates, and Recommendations for Isolate Submission and Reporting
 October 6, 2021
Prevention of Multidrug-resistant Organisms in Long-term Care Facilities. December 10, 2020

 Coordinated CRO/CPO Prevention Strategies



​Laboratory Identification


  • ​Ensure the laboratory rapidly notifies infection prevention and clinical staff when a patient or resident with CRO/CPO is identified.
  • Consider tracking CRE LabID events using the NHSN MDRO module (PDF).
  • Participate in the AR Lab Network Targeted Surveillance Program​ (PDF) to access confirmatory identification, antibiotic susceptibility and carbapenemase testing for CRAB at no cost. Contact for more information.
  • ​Know the local epidemiology and prevalence of CRO/CPO in your region.
  • Understand patient risk factors and high-risk facilities for CRO/CPO in your jurisdiction, such as long-term acute care hospitals (LTACH) and ventilator-equipped skilled nursing facilities (vSNF).
  • Work with local healthcare facilities to ensure awareness of CRO/CPO.

​Colonization Testing

  • ​Perform CPO colonization testing of patients and residents who are epidemiologically-linked to a patient newly identified with a CPO. Epi-linked patients include roommates, patients residing on the same unit, or patients exposed to the same medical device.
  • Consider performing CPO colonization testing upon admission of high-risk patients. High-risk patients include those admitted from LTACH or vSNF, or have received healthcare outside the United States during the prior 12 months.
  • ​Access CPO colonization testing services free of charge using the AR Lab Network. To learn more, contact the HAI Program to initiate a request.
  • Use the CPO Screening Decision Tree (PDF) to guide colonization testing recommendations in healthcare facilities.

Infection Control Measures

  • Place patients infected or colonized with CPO in a single room whenever possible, and implement Standard and Contact precautions; in skilled nursing facilities, if there is no evidence of transmission, place residents with risk factors for MDRO transmission on Enhanced Standard precautions.

Adherence Monitoring

  • ​During an outbreak, consider requesting the facility provide documentation of their own adherence monitoring.

Environmental Cleaning

  • ​Ensure thorough daily and terminal environmental cleaning. Focus on high-touch surfaces or any shared reusable medical equipment.
  • Review environmental cleaning checklists available on the CDPH HAI Program website.

​Interfacility Communication

  • ​Communicate CRO/CPO status to the receiving facility ahead of time to ensure appropriate care is maintained when transferring a patient/resident.
  • Use the HAI Program interfacility transfer form during all patient transfers available via the Interfacility Transfer Communications Guide webpage

  • ​Set expectations for facilities to communicate CRO/CPO status when transferring patients/residents to another healthcare facility.
  • During an outbreak, consider requesting facilities notify public health of all discharges and transfers involving individuals with CRO/CPO.

Antimicrobial Stewardship

  • ​Implement strategies to limit use of broad spectrum antimicrobial agents and an antimicrobial stewardship program (ASP) to promote and measure appropriate antimicrobial use by optimizing the selection, dosing, route, and duration of therapy.

  • Apply to be recognized as a top-performing ASP through the CDPH Antimicrobial Stewardship Honor Roll.

Regional Prevention


  • Contact the HAI Program for any suspected and confirmed CRO/CPO outbreaks.
  • Complete relevant investigation information in CalREDIE Lab and Epi Info tabs for CP-CRE and CPO (excluding CRE) conditions.

Additional CRO/CPO Resources

For additional information contact the HAI Program at

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