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Carbapenem-Resistant Acinetobacter baumannii

Closeup of Acinetobacter bacteria

Acinetobacter baumannii is a type of bacteria commonly found in the environment, including in soil and water. While generally harmless in the environment, Acinetobacter baumannii is a key cause of healthcare-associated infections, particularly in individuals who are immune-compromised. This is in part because many Acinetobacter baumannii bacteria are resistant to a group of antibiotics called carbapenems. Carbapenems are considered the last line of defense to treat multidrug-resistant bacterial infections, so infections caused by carbapenem-resistant Acinetobacter baumanii (CRAB) bacteria can be very difficult to treat. CRAB can cause pneumonia, as well as wound, bloodstream, and urinary tract infections.

Some types of CRAB (carbapenemase-producing CRAB) can pass on their resistance to carbapenem antibiotics to other bacteria and can lead to widespread antibiotic resistance.

It can be difficult to eliminate CRAB once it is found in a health care facility, since the organism can live on skin and may survive in the environment for months.

Healthy people do not usually get sick from CRAB. People with longer hospital or long-term care facility stays, open wounds, tracheostomies, or invasive devices like ventilators or urinary catheters are at risk for infection with CRAB. Individuals with weakened immune systems, chronic lung disease, or diabetes are also at risk for infection.

CRAB can be spread person-to-person in health care settings through direct contact with patients or residents who are colonized or infected with CRAB, or via health care workers’ hands following care of those people. It can also be spread via contaminated surfaces in the patient’s or resident’s environment.

Symptoms of CRAB infection will depend on which part of the body is affected. CRAB can cause many different types of infections, such as bloodstream, wound, urinary tract, and lung infections.

Because there is such a wide range of symptoms, a laboratory test is needed to see whether a patient has CRAB.

The most commonly prescribed antibiotics are not effective against CRAB infections. Treatment decisions should be made on a case-by-case basis by a health care provider.

People who are colonized with CRAB who do not show active signs of infection do not need to be treated or decolonized.

Carbapenemase-producing CRAB (CP-CRAB) became a reportable communicable disease condition in Wisconsin in July 2022. Data on CP-CRAB cases prior to that time are based on voluntary reporting of isolates by clinical laboratories to the Wisconsin State Laboratory of Hygiene.

As shown in the map below, there was an increase in the number of positive CP-CRAB clinical and colonized cases identified in Wisconsin in 2021, as compared to 2020. Other data points of interest include:

  • In 2020, three Wisconsin public health regions reported CP-CRAB cases compared to four regions in 2021.
  • In 2021, 15% of CP-CRAB cases were found to be pan-resistant, meaning they were resistant to all antimicrobials against which they were tested.
  • In 2021, among the 134 individuals for whom case history information was available, 90% (n=121) were either a current or former long-term care facility (LTCF) resident.

Reported CP-CRAB cases in Wisconsin


As of July 1, 2022, carbapenemase-producing carbapenem-resistant Acinetobacter baumannii (CP-CRAB) is a Category II reportable communicable disease condition in Wisconsin. See the Reportable Multidrug-Resistant Organism webpage for additional information about communicable disease reporting for this organism.

Wisconsin Department of Health Services resources
CDC resources


Questions about carbapenem-resistant Acinetobacter baumanii? Contact us!

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Last revised January 18, 2023