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CDC

Antimicrobial Resistance Lab Network

Carbapenem-Resistant Acinetobacter baumannii

Number of CRAB Isolates Tested

34,771

2017 – 2024

Percentage of CRAB with at least one targeted Carbapenemase Gene Detected

2.74%

955 CRAB with carbapenemase gene detected / 34,771 CRAB isolates tested

Most Common Carbapenemase in CP-CRAB

88.37% NDM

844 CRAB with NDM / 955 CP-CRAB

AR Lab Network Priority Area

Carbapenem-Resistant Acinetobacter baumannii

Acinetobacter is a particularly hardy and persistent pathogen. Carbapenem-resistant Acinetobacter can cause pneumonia as well as wound, bloodstream, and urinary tract infections.

In the United States, most carbapenem-resistant Acinetobacter contain mobile genetic element(s) carrying resistance genes such as carbapenemases that are easily shared between bacteria. These elements make carbapenem antibiotics ineffective by degrading these important drugs. In the AR Lab Network, CP-CRAB is defined as carbapenem-resistant Acinetobacter baumannii isolates having at least one targeted carbapenemase gene. CDC targets CP-CRAB for detection and response because they can be spread easily and because they are resistant to nearly all available antibiotics.

The AR Lab Network routinely performs molecular testing to identify the presence of the following five targeted carbapenemase genes:

  • Klebsiella pneumoniae Carbapenemase (KPC)
  • New Delhi Metallo-beta-lactamase (NDM)
  • Verona Integron-encoded Metallo-beta-lactamase (VIM)
  • Imipenemase Metallo-beta-lactamase (IMP)
  • Oxacillinase-48-like beta-lactamase (OXA-48)

Other mobile oxacillinase (OXA) genes, such as OXA-23, OXA-24/40, OXA-58, are known to be common in CRAB. The AR Lab Network does not routinely test for these OXA genes. For more information about detection of these other OXA genes in CRAB in the AR Lab Network, see CRAB feature item.

AR Lab Network data are presented in both aggregated and year-to-year formats. The AR Lab Network is not a traditional surveillance system; changes in year-to-year carbapenemase rates may also be reflective of year-to-year changes in testing priorities, methods, or volume, jurisdictional reporting criteria, and other factors. Year classification is defined by specimen collection date.

Data Source
AR Lab Network
Years Included
2017 - 2024
Resources

Carbapenemase Gene Detection

Carbapenemase-positive (CP) means that an organism is positive for carbapenemase activity and/or has at least one of the five targeted carbapenemase genes detected. The frequency of carbapenemase gene detection varies by organism and is driven by several factors, including antibiotic use, environmental persistence, and infection control practices in individual healthcare facilities, and regional spread from nearby geographic locations.

Carbapenemases Detected in CRAB or CP-CRAB, by All Years

Targeted Genes Detected

Select data visualizations using the tabs above to view denominator or isolate type data. This graph displays the distribution of carbapenemases detected among CRAB or CP-CRAB isolates in the United States from 2017 - 2024. To view the number of isolates with CP Gene not detected, select “add a comparison”.

Note: The AR Lab Network does not routinely test for other mobile oxacillinase (OXA) genes known to be common in CRAB. Additional information on more common genes in CRAB can be found in the Featured Item.

Geographic Locations

The frequency of targeted carbapenemase gene detection varies by location and is driven by several factors, including antibiotic use and infection control practices in individual healthcare facilities, the underlying health and age of the patient population, and regional spread from nearby locations.

Carbapenemase Genes Detected in CRAB, by Year(s) and Region

This map displays the percentage of CRAB with targeted gene(s) detected, by AR Lab Network Region, from 2017 - 2024.

Note: The AR Lab Network does not routinely test for other mobile oxacillinase (OXA) genes known to be common in CRAB. Additional information on more common genes in CRAB can be found in the Featured Item. View a map of the AR Lab Network regions on the CDC website.

Carbapenemase Genes Detected in CRAB or CP-CRAB, by All Years and Region

KPC DetectedNDM DetectedVIM DetectedIMP DetectedOXA-48 Detected

Select data visualizations using the tabs above to view denominator or isolate type data. This graph displays the distribution of carbapenemases detected among CRAB or CP-CRAB isolates, by AR Lab Network Region, in 2017 - 2024. To view the number of isolates with CP Gene not detected, select “add a comparison”.

Note: The AR Lab Network does not routinely test for other mobile oxacillinase (OXA) genes known to be common in CRAB. Additional information on more common genes in CRAB can be found in the Featured Item. View a map of the AR Lab Network regions on the CDC website.

Antimicrobial Susceptibility to Carbapenem Drugs

Antimicrobial susceptibility testing (AST) is a laboratory procedure that determines whether antibiotics, like carbapenems, might be effective in treating the bacteria being tested. Susceptibility to carbapenems may vary by the presence of a carbapenemase gene. Understanding how carbapenemase genes can affect carbapenem susceptibilities can help improve surveillance and detection of carbapenemase genes by setting containment priorities and helping to identify isolates for AR Lab Network testing.

Susceptibility to carbapenem drugs, by carbapenemase gene, 2017 - 2024

This table shows the percentage of CRAB isolates that were not susceptible or had an intermediate or resistant interpretation for each carbapenem tested, by the presence or absence of a targeted carbapenemase gene. These data may be used by public health officials to recommend specific phenotypic definitions that will enhance reporting and submission of clinical isolates to public health for enhanced detection and surveillance of carbapenemase genes. This table is not intended to provide any information to assist with clinical decision making.

Antimicrobial susceptibility testing results were interpreted using the most current version of the CLSI M100 document for breakpoints where available.

* Isolates positive for more than one carbapenemase gene and isolates positive for carbapenemase activity but negative for all five targeted carbapenemase genes were excluded from the analysis.

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Footnotes

  • The AR Lab Network was not designed to be a traditional surveillance system. Isolates tested are a convenience sample and include clinical, surveillance, and outbreak specimens. Within each state, isolate submissions and testing are determined by state priorities and reporting regulations.
  • A map of the AR Lab Network regions is available at https://www.cdc.gov/antimicrobial-resistance-laboratory-networks/php/about/.
  • CP Isolates are defined as those testing positive for carbapenemase activity and/or any of the five targeted genes (KPC, NDM, VIM, IMP, OXA-48).
  • Carbapenem-resistant Enterobacterales (CRE) isolates were resistant to ertapenem, imipenem, meropenem, or doripenem using antimicrobial susceptibility testing breakpoints.
  • Carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates were resistant to imipenem, meropenem, or doripenem, using antimicrobial susceptibility testing breakpoints.
  • Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates were resistant to imipenem, meropenem, or doripenem, using antimicrobial susceptibility testing breakpoints.
  • Carbapenemase gene screens aimed to detect colonization with bacteria carrying at least one of five targeted carbapenemase genes. Screens were positive when at least one of five targeted carbapenemase genes (KPC, NDM, VIM, IMP, OXA-48) was detected using real-time polymerase chain reaction (PCR).
  • Suggested Citation: CDC. Antibiotic Resistance & Patient Safety Portal (AR&PSP) AR Lab Network Data. Atlanta, Georgia: U.S. Department of Health and Human Services, CDC. https://arpsp.cdc.gov/.
  • Data displayed are updated as of June 2025. Given the structure of the AR Lab Network and its testing strategies, supplementary testing and the availability of improved methods and additional data may result in changes or corrections to data reported on PSP.