Screening for Candida auris colonization in healthcare settings

Key points

Patients or residents of healthcare facilities^* can be asymptomatically colonized with C. auris, meaning they have it on or in their body but without causing an infection.
Colonized patients or residents can spread C. auris to other patients or residents, so appropriate infection prevention and control measures should be implemented based on screening results to help prevent spread.
Screening to identify patients or residents who are colonized with C. auris can be conducted by testing swabs of the skin.
The screening strategy should be informed by local epidemiology, patient risk factors, facility characteristics, and the intended purpose of screening.

Background

C. auris is an emerging, frequently antimicrobial-resistant yeast that can cause severe illness. Patients or residents in healthcare facilities can be asymptomatically colonized with C. auris. They can subsequently spread the fungus to other patients through contaminated surfaces (e.g., bedrails, bedside tables), shared mobile medical equipment (e.g., glucometers, ultrasound machines) or the hands or clothing of healthcare personnel. Because C. auris can persist on patients and surfaces for long periods of time and many commonly used hospital grade disinfectants are not effective against it, C. auris can spread easily among patients and cause outbreaks in healthcare settings.

Screening

Screening for C. auris colonization is a key strategy to prevent spread in healthcare facilities and can be conducted by testing swabs taken from the skin of facility patients or residents. Identifying patients or residents who are colonized allows healthcare facilities to implement appropriate infection prevention and control measures, including use of barrier precautions and disinfectants that are effective against C. auris.

Deciding which patients or residents to screen and how often to perform screening should be based on several factors, including the local C. auris epidemiology and burden, epidemiologic linkages to other cases, patient risk factors, and the purpose of screening.

Detailed guidance for who to screen and when to perform C. auris colonization screening can be found in the Interim Guidance for a Public Health Response to Contain Novel or Targeted Multidrug-resistant Organisms (MDROs) [PDF – 24 pages] [Containment Strategy | HAI | CDC] and Interim Guidance for Public Health Strategies to Prevent the Spread of Novel or Targeted Multidrug-resistant Organisms (MDROs) [PDF – 21 pages] [Prevention Strategy | HAI | CDC]. These guidance documents apply to multiple multi-drug resistant organisms, including C. auris, and to all healthcare facility types, allowing implementation and adaptation of strategies and measures based on local burden and epidemiologic stage as well as facility type.

Recommendations

Who and when to screen

Consider screening patients who are at high risk for C. auris colonization, such as:

Those with an epidemiologic link to a patient or resident who is infected or colonized with C. auris. Examples of epidemiologic links include
- sharing the same room, unit, or other care areas as a patient or resident with C. auris, even if that person has been discharged,
- receiving care from the same healthcare personnel during the same time as a person with C. auris, or
- being exposed to common mobile medical equipment that was used by a patient or resident with C. auris, especially if there are concerns about adequate cleaning and disinfection.
Patients with current or previous healthcare encounters at facilities including:
- Facilities with currently suspected or confirmed C. auris transmission
- High acuity post-acute care facilities including long-term acute care hospitals [LTACHs] and ventilator-capable skilled nursing facilities [vSNFs]
- Facilities located outside the United States or in a part of the country https://www.cdc.gov/fungal/candida-auris/tracking-c-auris.html with a high burden of C. auris
Patients with risk factors for acquiring C. auris, including:
- Mechanical ventilation
- Indwelling medical devices, including central lines, feeding tubes, urinary catheters, etc.
- Receipt of complex or high acuity medical care
- Frequent or long healthcare stays, especially at high-risk facilities
- Colonization or infection with other multidrug-resistant organisms

Screening strategies for different scenarios

Screening can be conducted using a prevention-based approach (i.e., not in response to a newly identified case), or a response-based approach (i.e., after detection of a new C. auris case). Screening can be conducted at different points during a patient’s healthcare stay, depending on the goal. Patients might be screened
- on admission to identify new introductions of C. auris cases needing appropriate infection prevention and control precautions and to identify other facilities with C. auris cases or transmission,
- during a healthcare stay to identify new cases resulting from intra-facility transmission or to assess the effectiveness of infection control interventions, or
- at discharge or transfer to identify patients or residents needing appropriate infection prevention and control precautions at a receiving facility. However, screening should be used to inform infection control strategies to prevent transmission and not be used to deny or delay transfers.

Scope of screening

Screening can often be conducted using a broad approach by conducting a point prevalence survey (PPS) (e.g., screening of all patients or residents on a unit or in a facility at the time), or by using a more targeted approach (e.g., screening only certain patients based on risk factors, epidemiologic links, or clinical characteristics). However, broad screening using PPSs is preferred because a targeted approach may miss patients who are colonized but did not have epidemiologic links to a known case or presence of risk factors.

Follow-up screening: Wider screening or follow-up response screening after a PPS is often recommended if there is evidence or suspicion for ongoing transmission and considerations for those are described in more detail in the MDRO containment guidance. In addition to response-based screening, routine prevention-based screening may be recommended by health departments at certain frequency intervals as described in the MDRO prevention guidance.

Reassessment of colonization: CDC does not recommend re-screening patients known to be infected or colonized with C. auris because patients in healthcare settings can be colonized for a prolonged period, perhaps indefinitely. Colonized patients and residents may intermittently have negative results followed by a positive result. Negative results for a colonized patient should not be used to discontinue implementation of appropriate infection prevention and control precautions.

Healthcare worker screening: CDC does not recommend screening healthcare workers for C. auris. Following recommended infection control precautions including barrier precautions and hand hygiene will prevent spread to healthcare workers. During studies performed during previous C. auris outbreaks, screening found that colonization of healthcare workers happened rarely, if at all.

How to screen

For C. auris colonization screening, CDC recommends using a composite swab of the patient’s bilateral axilla (i.e., armpit) and groin, meaning one swab that is used to swab both axilla and groin areas. Available data suggest that these sites are the most common and consistent sites of colonization, although other body sites may also be colonized, and research continues to explore the best method for assessing colonization.

Information about procedures for collecting patient swabs and informing patients about why screening is being conducted can be found on the CDC website, Procedure for Collection of Patient Swabs for Candida auris.

Testing for C. auris colonization is available through CDC’s Antimicrobial Resistance Laboratory Network (AR Lab Network). The AR Lab Network performs this testing free of charge, although this testing may require coordination through the healthcare-associated infection, antimicrobial resistance, or multidrug resistance program of your state public health department. To learn more about using the AR Lab Network to conduct colonization screening and to see the list of AR Lab Network regional laboratories to know which one covers your jurisdiction and who to contact for questions or support, visit the CDC webpage on How AR Lab Network Works. Some public health, academic, clinical, and commercial laboratories may also offer C. auris colonization screening. For laboratories interested in performing colonization testing in house, see CDC’s Guidance for Detection of Colonization of Candida auris.

* For this guidance, the term ‘healthcare facility’ refers to all acute care hospitals and post-acute care facilities that care for patients or residents who remain overnight and require medical care, nursing care or rehabilitation services. This generally excludes assisted living facilities.

diagram showing connectivity between people

Who to screen

Consider screening patients who are at high risk for C. auris, including:

Close healthcare contacts of patients with newly identified C. auris infection or colonization (see the section below for more information).
Patients who have had an overnight stay in a healthcare facility outside the United States in the previous one year, especially if in a country with documented C. auris cases. Strongly consider screening when patients have had such inpatient healthcare exposures outside the United States and have infection or colonization with carbapenemase-producing Gram-negative bacteria. C. auris co-colonization with these organisms has been observed regularly.

Screening of close healthcare contacts

Health departments and healthcare facilities should consider a number of factors when deciding which patients to screen who have had contact with a patient with C. auris infection or colonization (referred to here as index patients). At a minimum, screen roommates at healthcare facilities, including nursing homes, where the index patient resided in the previous month. Ideally, identify and screen roommates of the index patient even if they were discharged from the facility. Consider also screening patients who require higher levels of care (e.g., mechanical ventilation) and who overlapped on the ward or unit with the index patient for 3 or more days, as these patients are also at substantial risk for colonization. Patients with newly identified C. auris infection or colonization might have been colonized for months before detection of the organism. Therefore, it is also important to consider the patient’s prior healthcare exposures and contacts when devising a screening strategy.

Screening to detect ongoing transmission

Health departments and healthcare facilities should strongly consider performing more extensive screening, such as a point prevalence survey, if there is evidence or suspicion of ongoing transmission in a facility (e.g., C. auris detected from multiple patients through contact screening or clinical cultures, increase in infections from unidentified Candida species). In a point prevalence survey, every patient on a given unit or floor where transmission is suspected should be screened. Consider doing a point prevalence survey even if all known C. auris patients have been discharged.

Screening Resources

How to screen

Testing for C. auris colonization screening is available through CDC’s AR Lab Network. The AR Lab Network performs this testing free of charge, although this testing may require coordination through the healthcare-associated infection (HAI) program of your state public health department (view state HAI contacts). To learn more about using the AR Lab Network and to find a listing of AR Lab Network regional laboratories, visit this webpage on How AR Lab Network Works. Additionally, CDC and some public health laboratories may be able to assist with C. auris colonization screening.

For laboratories interested in performing swab testing in-house, guidance on processing swabs to assess for C. auris colonization see CDC’s Guidance for Detection of Colonization of Candida auris. At this time, commercial testing for C. auris screening is not available.

Screen for C. auris colonization using a composite swab of the patient’s bilateral axilla and groin. Available data suggest that these sites are the most common and consistent sites of colonization. Although patients have been colonized with C. auris in the nose, mouth, external ear canals, urine, wounds, and rectum, these sites are usually less sensitive for colonization screening. Consult with local or state public health department and CDC for more information on assessing C. auris colonization.

When screening identifies a patient with C. auris colonization, use the same infection control precautions as for patients with C. auris infection. While awaiting screening results, healthcare facilities could consider placing patients at highest risk of C. auris colonization on appropriate transmission-based precautions. Examples of patients at highest risk include patients from healthcare facilities with high prevalence or ongoing transmission or patients with recent overnight stays in countries with documented C. auris cases.

Additional guidance on screening is available in the Interim Guidance for a Health Response to Contain Novel or Targeted Multidrug-resistant Organisms [PDF – 10 pages].