Different mechanisms cause the carbapenem resistance, with carbapenemase-producing CRE (CP-CRE) considered primarily responsible for the increase in the spread of CRE. CP-CRE produce enzymes that break down many antibiotics: penicillins, cephalosporins, monobactams, and carbapenems. This trait is most commonly seen in Enterobacteriaceae , which include clinically important bacterial species such as Escherichia coli (E. coli ) and Klebsiella pneumoniae . Because of the public health risk CRE poses, predominantly attributed to the rapidly spreading CP-CRE, healthcare facilities must implement stringent infection control practices to reduce CRE-associated transmission and to ensure that healthcare settings remain safe for patients. Many toolkits and guidance documents exist to assist healthcare workers and infection control specialists to design and implement their CRE prevention policies. CRE is commonly associated with clusters and outbreaks in healthcare settings and is responsible for increasing morbidity, mortality, and healthcare costs worldwide. In the United States, 42 States over the past decade have had at least one type of CRE infection diagnosed in their medical facilities. Carbapenem resistance can be transferred between patients and between different species of bacteria via plasmids, allowing the rapid spread of the resistance gene within healthcare and community settings. Although CRE are largely associated with nosocomial transmission, species within the Enterobacteriaceae family (such as E. coli) have been associated with community-acquired infections and outbreaks in the past. Therefore, as CRE becomes more prevalent, both nosocomial and community transmission should be considered when developing prevention efforts. Mortality among patients with CRE infections can be as high as 40 to 50% due to both the severity of the infections and the lack of effective antibiotics with which to treat them. Because of their increasing global incidence and associated morbidity and mortality, the World Health Organization has identified CRE as critical pathogens requiring focused prevention research. 86 Contact precautions to prevent CRE infections Contact precautions are one of three types of transmission-based precautions to control the spread of infectious diseases, the other two being airborne and droplet precautions. Contact precautions are currently recommended to prevent nosocomial transmission of CRE for patients with known or suspected infections or at an increased risk of infection with CRE. Maintaining appropriate contact precautions can be challenging for patients undergoing procedures or those who are critically ill and require intensive patient care. Contaminated stool and bodily fluids can transmit CRE, making environmental contamination a concern for patients who are incontinent, who have draining wounds or secretions, or who require high levels of care. Patient transport within and between healthcare facilities also complicates strict adherence to contact precautions.
However, when successfully implemented, contact precautions have been shown to reduce transmission of CRE in healthcare facilities. Contact precautions include appropriate patient placement (e.g., single-patient spaces), use of personal protective equipment, a reduction in the movement and transportation of the patient, the use of disposable or dedicated patient-care equipment, and the frequent and thorough cleaning of patient spaces (especially high-touch surfaces and equipment in close proximity to the patient). Variations on implementation of contact precautions differ by setting, risk of transmission, and the type of care being provided. • Some level of patient isolation should also be a part of contact precautions when feasible. This may include: • Isolating carriers or individuals infected with CRE in single rooms with attached bathrooms • Isolating carriers into rooms shared only by other patients colonized or infected with the same pathogen • Cohorting staff (to reduce staff-to-patient transmission), defined as using a dedicated team of healthcare staff to care for patients infected with a particular multi-drug resistant organism (MDRO) • Prioritizing patients at higher risk of transmission for single rooms, and rooming the remaining carriers or infected individuals together Of these options, single patient rooms are always preferred whenever possible. The placement of appropriate signs outside patient rooms is essential to alert staff and visitors to the isolation status of the patient(s) whose room(s) they are entering. In addition to the contact precaution practices described above—particularly during invasive procedures—contact precautions may include full- head protection and/or face masks. When feasible, individual supplies and equipment dedicated to a colonized patient should be used. However, more studies are needed to determine which variations or additions to contact precautions improve control of CRE transmission. Initiating contact precautions Contact precautions are often initiated following a positive screening test. Active screening using perirectal swabs or swabs of other body sites may be used to screen patients for CRE colonization for the purpose of initiating contact precautions. The European Centers for Disease Control and Prevention (ECDC) recommends active screening on admission to specific wards or units (e.g., oncology units), during outbreak scenarios, and upon admission to a hospital. 87 Active surveillance (upon admission) may not be appropriate in all settings. In units that regularly perform contact precautions, such as ICUs, active screening may be unnecessary. For some organisms, such as extended-spectrum beta-lactamase (ESBL)-producing bacteria, active surveillance
has not been found to reduce transmission. Active surveillance also may not be appropriate in settings where the prevalence is low. Passive surveillance may be sufficient to reduce transmission in low- endemicity settings—initiating contact precautions only if a CRE infection is identified during the course of clinical care, as opposed to screening upon admission. Pre-emptive isolation relies on identifying CRE carrier risk factors at admission to the facility, which requires information about potential risks. The CDC recommends isolating patients who transfer from high-risk settings (e.g., hospitals in endemic areas or facilities with known outbreaks). Further research is needed to design a decision tree or risk score that can be used as a simple and accurate screening tool in a variety of settings. A study performed at the Johns Hopkins Hospital found that despite their assessed risk factors at admission (history of vancomycin-resistant Enterococcus, methicillin-resistant Staphylococcus aureus , and/ or multi-drug-resistant gram-negative organisms), 57 percent of CRE-colonized patients and 50% of patients colonized with CP-CRE were not isolated with contact precautions. 88 The Johns Hopkins study demonstrates that even with a review of a patient’s history at the time of hospital admission, many CRE carriers are missed, and are placed on contact precautions only after a positive clinical culture is isolated. This type of study is valuable for determining the positive predictive value of existing methods for preemptively assessing risk, and similar research is needed to assess the risk prediction models suggested in other studies and guidance documents. There is currently no global consensus on whether it is appropriate, or when it is appropriate, to discontinue contact precautions. The CDC recommends that contact precautions be continued indefinitely. However, some recommend discontinuation on a case-by-case basis if: (1) at least 6 months have elapsed since a positive culture, and (2) at least two consecutive negative cultures were collected at least one week apart. BEFORE MOVING ONTO THE NEXT SECTION, PLEASE COMPLETE CASE STUDY 5 ON THE NEXT PAGE. Implementation Fostering a workplace environment that encourages consistent use of contact precautions requires multi-institutional stakeholder involvement. Local health departments and large health systems may mandate contact precautions for patients with CRE infections. On a facility level, administrators and infection control specialists should encourage appropriate contact precautions by implementing monitoring and compliance audits as well as education of staff, patients, and visitors. Cross-sectional surveys have found that CRE acquisition is negatively correlated with workplace factors such as lack of staff engagement in infection control efforts and the impression that the work environment is overwhelming, stressful, and chaotic.
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