Candida auris, clinical
2023 Case Definition

Background

Candida auris (C. auris) is an emerging multidrug-resistant yeast that can colonize the skin and cause invasive infections. It can spread readily between patients in healthcare facilities, causing numerous outbreaks that have been difficult to control. Containment of C. auris spread largely depends on timely detection and implementation of appropriate infection prevention and control measures (1).

Laboratory Criteria

Confirmatory laboratory evidence:

• Detection of C. auris in a specimen from a swab obtained for the purpose of colonization screening using either culture or validated culture-independent test (e.g., nucleic acid amplification test [NAAT]), OR
• Detection of C. auris in a clinical specimen obtained during the normal course of care for diagnostic or treatment purposes using either culture or a validated culture-independent test (e.g., NAAT)

Note: The categorical labels used here to stratify laboratory evidence are intended to support the standardization of case classifications for public health surveillance. The categorical labels should not be used to interpret the utility or validity of any laboratory test methodology.

Criteria to Distinguish a New Case from an Existing Case

A patient who is colonized or infected with C. auris is considered colonized indefinitely. The following provides guidance for health departments to distinguish a new case for patients who test positive for C. auris in either a screening swab (i.e., screening case) or in a clinical specimen (i.e., clinical case).

• For screening cases, count patient only once as a screening case; do not count if patient has been previously identified as a clinical or screening case. A person with a screening case can be later categorized as a clinical case (e.g., patient with positive screening swab who later develops bloodstream infection would be counted in both categories).
• For clinical cases, count patient only once as a clinical case, even if the patient has already been counted separately as a screening case. A person with a clinical case should not be counted as a screening case thereafter because all clinical cases are considered to also be colonized with C. auris (e.g., patient with clinical C. auris specimen who later has positive screening swab is not counted as a screening case).

Confirmed

Person with confirmatory laboratory evidence from a swab collected for the purpose of screening for C. auris colonization regardless of site swabbed.**

**Typical screening specimen sites are skin (e.g., axilla, groin), nares, rectum, or other external body sites. Swabs collected from wound or draining ear as part of clinical care are considered clinical specimens.^‡

‡Because it can be difficult to differentiate screening specimens from clinical specimens based on microbiology records, any swabs except wound swabs or draining ear swabs can be assumed to be for screening unless specifically noted otherwise. Laboratories do not need to change their practice; public health wants to identify all C. auris whether from screening or clinical specimens.