Nurses are well aware of the problems with multidrug-resistant organisms (MDROs) and their ubiquitous presence across health care settings. Care issues and outcomes among patients with MDROs such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), and Clostridioides difficile (C. diff) have increased awareness, but MDROs remain a growing challenge in the provision of care in virtually all health care settings.

Carbapenem-resistant Gram-negative bacteria, another example of MDROs, have emerged as one of the most urgent public health challenges globally. Organisms such as carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and carbapenem-resistant Acinetobacter baumannii (CRAB) are associated with high morbidity, mortality, prolonged hospitalization, and limited treatment options. According to the World Health Organization (WHO), carbapenem-resistant A. baumannii and carbapenem-resistant Enterobacterales are among the highest-priority pathogens due to their rapid spread and severe clinical consequences (WHO, 2024).

Mechanisms of Carbapenem Resistance

Carbapenem resistance develops when bacteria change in ways that allow them to survive despite antibiotic treatment. Nurses and other health care personnel benefit from understanding these mechanisms because they directly relate to infection prevention activities, equipment cleaning and disinfection, and antimicrobial stewardship efforts.

Examples of how resistance develops are outlined below:

  1. Bacteria Produce Enzymes That Break Down the Antibiotic (Carbapenemase production)

Some bacteria create special enzymes that destroy carbapenem antibiotics before they can work. These are called carbapenemases. Common types of these enzymes include KPC (Klebsiella pneumoniae carbapenemase), NDM (New Delhi metallo-beta-lactamase), VIM (Verona integron-encoded metallo-beta-lactmase), IMP (Imipenemase metallo-beta-lactamases), and OXA-48 (Oxacillinase-48).  These enzyme abbreviations/names may be familiar, as they have been seen on microbiology laboratory reports. These enzymes can be shared between bacteria through plasmids, small pieces of DNA that bacteria carry in addition to their main chromosome. Plasmids can easily move from one bacterium to another, allowing bacteria to share traits—such as antibiotic resistance—very quickly (Aurilio, 2022). Simply speaking, the bacteria that create these carbapenemases are now able to ‘chew up’ antibiotics so that they cannot work.

  1. Bacteria Close the ‘Doorways’ Antibiotics Use to Enter (Porin Changes)

Carbapenem antibiotics such as imipenem, meropenem, ertapenem, and doripenem need to enter the bacterial cell to work. Bacteria have tiny “doorway” channels called porins. Some MDROs close these doorways, make them smaller, or reduce their number. This prevents the antibiotic from getting inside the cell (Aurilio 2022).

  1. Bacteria Pump the Antibiotic Back Out (Efflux Pumps)

Some resistant bacteria have efflux pumps—tiny mechanisms that actively pump antibiotics out of the cell. Even if the drug manages to enter the cell, the pump removes it back out before it can work. This mechanism is particularly important in Pseudomonas aeruginosa and Acinetobacter baumannii (Aurilio 2022).

Preventing the Spread of these Organisms in the Health Care Environment

Now that we know how carbapenem resistance impacts the bacterial cell and how it makes antibiotics ineffective, what do we need to know about how the health care environment enables movement of these organisms to patients, thereby presenting risks of MDRO infection?

Environmental Reservoirs and Transmission

The health care environment is a major reservoir for MDROs. These bacteria can survive for days to months on surfaces, especially when cleaning and disinfection practices are inconsistent or when high patient acuity increases contamination levels. High-touch surfaces such as bed rails, call bells, pumps, ventilator components, and other pieces of shared equipment or devices are frequently affected (CDC, 2025; CDC, 2024).

Environmental Cleaning and Disinfection

Key principles of environmental cleaning and disinfection include:

  • Prioritizing high-touch and frequently touched surfaces for cleaning and disinfection. This may need to be done several times throughout each day.
  • Cleaning furniture and equipment, then using a disinfectant that is EPA-registered for use in health care settings. This helps ensure that the disinfectant is effective against the MDRO.
  • Ensuring the disinfectant stays in contact with the furniture or equipment for the correct contact time. That means the item was completely cleaned, then a disinfectant applied to the entire item, and that disinfectant was allowed to dry undisturbed for the contact time listed on the product label.
  • Conducting thorough cleaning and disinfection of the entire room at discharge.
  • Disinfecting shared equipment between every patient. Never share equipment unless it has been cleaned and disinfected prior to use.
  • Monitoring cleaning quality and sharing results with the environmental services personnel and/or others responsible for environmental cleaning and disinfection.

(CDC Environmental Cleaning Guidelines)

Nursing Actions to Prevent Transmission

Nurses also play a critical role in preventing spread by practicing basic infection prevention and control practices such as hand hygiene, following isolation protocols, educating patients and families about isolation and hand hygiene, monitoring the practices of other health care personnel entering and exiting the patient environment, and ensuring shared equipment is cleaned and disinfected upon removal from the isolation room and prior to use on other patients.

Preventing transmission is a vital nursing action, and it is also important that nurses use their assessment and communication skills to rapidly respond to situations where MDROs are recognized so patients can be quickly moved into an isolation environment. In addition, implementation of antimicrobial stewardship activities such as use of evidence-based practices to collect specimens, timely removal of invasive devices, maintenance of antimicrobial administration schedules, and collaboration with medical, pharmacy, and microbiology team members regarding care of patients identified with an MDRO are critical elements of an infection prevention program.

Conclusion

Carbapenem-resistant Gram-negative organisms represent a growing global threat. They use several strategies—breaking down antibiotics, blocking entry, and pumping drugs out—to resist treatment. Because of these challenges, prevention is essential. Nurses play a vital role by performing hand hygiene, following isolation precautions, ensuring equipment disinfection, and supporting antimicrobial stewardship.

Ruth Carrico, PhD, FNP-C, CIC, FSHEA, FNAP, FAAN, is an adjunct professor, Division of Infectious Diseases, University of Louisville School of Medicine, Louisville, KY.

Michael Curran, MPH, BSN, CIC, NHDP-BC, is an infection control nurse/MDRO prevention lead, Kentucky Department for Public Health.