Guidance

Introduction and background

Updated 19 March 2025

Note: numbers in round brackets refer to references which can be found in the References section.

Introduction

In 2024, Candida auris was proposed as the type species of a novel yeast genus Candidozyma (as Candidozyma auris) to reflect its distant relationship to the principal Candida species – C. albicans complex, C. tropicalis and C. parapsilosis complex (1). Throughout this guidance C. auris will be used in place of both the new and former designation.

This guidance is relevant to the laboratory investigation, management, and infection prevention and control (IPC) practices associated with C. auris in a healthcare setting. This update supersedes the previous guidance, released in 2017.

Who these guidelines are for

These guidelines are intended for healthcare professionals in acute NHS and independent sector healthcare settings in England, including laboratory personnel and IPC teams. The guidance is designed to support the development of local policies and can serve as a framework for clinical audit and quality improvement initiatives.

It may also be used by clinical and public health professionals involved in the management of healthcare-associated outbreaks of C. auris.

Further infection control guidance in community care setting can be found at Candida auris: infection control in community care settings.

For queries relating to this document, please contact cauris@ukhsa.gov.uk

What has changed

Changes to the previous version of guidance include:

• updated nomenclature of C. auris
• updated global and national epidemiology - data on laboratory reporting to the Second-Generation Surveillance System (SGSS) has been provided up until the end of December 2024, cross-referenced with UKHSA Mycology Reference Laboratory (MRL), NHS Mycology Reference Centre Manchester and NHS Mycology Reference Centre Leeds data
• investigation in laboratories expanded to include sub-sections addressing culture, biochemical, proteomic and molecular identification in greater detail, in addition to a new section covering clade typing and whole genome sequencing (WGS)
• screening section expanded to include recommendations and considerations for patient and contact screening, including screening sites and setting specific screening
• updates regarding the management of positive patients with isolation, de-isolation and cohorting recommendations, including considerations for screening of multi-drug resistant organisms (MDROs)
• updates regarding decolonisation and skin antisepsis
• new section on antimicrobial stewardship and its relevance to C. auris infection
• updated IPC section outlining principal measures to be undertaken to prevent transmission of C. auris
• greater detail provided on modes of transmission and the ability of C. auris to contaminate and persist in the healthcare environment
• new section on the management of invasive medical devices
• updated sections on the safe management of care equipment and the care environment, with an expanded section on decontamination
• new section on notification, reporting and information sharing responsibilities for healthcare providers, including outbreak notification. Updated case and outbreak definitions are provided

Guideline development

Evidence base

The guidance has been updated in line with the latest available evidence from published literature (2), international best practice, and expert consensus, alongside insights from national surveillance.

The evidence base, identified through a review of published literature since the 2017 publication, predominantly comprised cohort studies, case-control studies, before-and-after studies, laboratory investigations, environmental surveys, and outbreak reports. In some areas, expert opinion was also considered, particularly where no direct evidence was identified.

The strength of evidence supporting the recommendations was not formally rated due to the nature of the available evidence.

Development of recommendations

The recommendations were developed by a multidisciplinary group and represent examples of good practice, based on expert opinion informed by the available evidence.

Although the working group identified recommendations as best practice, no cost-effectiveness studies were available to directly inform implementation costs. Recommendations relating to laboratory procedures and screening practices require local risk assessment ^{[footnote 1]} and contextual considerations before adoption.

Stakeholder engagement

This guidance incorporates feedback received from stakeholders via the public consultation on the draft guidance held in 2023. A sub-group of the working group reviewed stakeholders’ comments and collectively agreed revisions.

Background

C. auris is a rapidly emerging fungal pathogen with a global distribution. First identified in 2009 from the external auditory canal of a patient in Japan (3), it has now been identified across 6 continents, in over 60 countries worldwide.

Designated a critical priority fungal pathogen by the World Health Organization in 2022 (4), severe invasive infections may occur, associated with high mortality, seen mostly within healthcare settings. C. auris can cause a wide variety of infections in both adult, paediatric and neonatal populations, including bloodstream, intra-abdominal, bone and cerebrospinal fluid (CSF) infections through to superficial skin infections. C. auris has developed resistance to many available classes of antifungals, with emergence of pan-resistant strains (5).

C. auris can grow at higher temperatures than many other fungi and is able to tolerate high salt concentrations. These are important characteristics in its ability to persist in the environment and survive for prolonged periods of time.

C. auris can spread between patients, indirectly via contamination of the environment or equipment, or via transient colonisation of healthcare workers (6). Colonisation (carrying C. auris without signs or symptoms) usually precedes invasive infection and can be detected through surveillance swabs. Swabs from the axilla, groin and nose are the optimal sites for patient screening, with the axilla and groin often sampled together as a composite swab.

The ability to readily transmit, colonise skin and survive for prolonged periods of time in the environment contributes to the increased outbreak potential of C. auris. This highlights the need for prompt, effective and sustained IPC practices. Acquisition can be rapid (as little as 4 hours from initial exposure to colonisation in affected units) (7), and colonisation can be prolonged (weeks or months from acquisition) (8).

Review of international literature has highlighted that infections largely occur within the augmented care setting, especially high-dependency and critical care units ^{[footnote 2]}. Additionally, there have been reports of detection within long-term care facilities in the USA, with colonisation rates found to be highest in long-term nursing facilities providing ventilator support (9).

Additionally, there have been reports of detection within long-term care facilities in the USA, with colonisation rates found to be highest in long-term nursing facilities providing ventilator support (9).

Over the past 18 months, C. auris isolates detected in England have been mainly linked to known UK outbreaks or sporadic introductions associated with patients with known connections to endemic countries, often originating from the independent health sector. A much smaller proportion of isolates from the UK have been identified in patients with no known links to outbreaks or overseas healthcare exposure.

Possible risk factors for developing C. auris colonisation or infection include (10):

• healthcare abroad, including repatriations or international patient transfers to UK hospitals for medical care, especially from countries with ongoing transmissions (2)
• recent surgery, including vascular surgery within 30 days
• prolonged stay in critical care
• severe underlying disease with immunosuppression, such as HIV and bone marrow transplantation
• corticosteroid therapy
• neutropenia
• malignancy
• chronic kidney disease or diabetes mellitus
• mechanical ventilation
• presence of a central-venous catheter or urinary catheter
• extra-ventricular CSF drainage device
• prolonged exposure to broad-spectrum antibiotic or antifungal use
• underlying respiratory illness

Mortality associated with invasive C. auris is variably reported, with estimations of case fatality rate (CFR) between 30 and 72% (11). This is due, in part, to severe underlying conditions in at-risk populations, with attributable mortality being difficult to determine and likely much lower than the reported CFR. There is also variability between different countries, which may be associated with differences in epidemiology and clade, multi-drug resistance, and the limited availability of certain antifungal drugs in some countries.

Global epidemiology

C. auris is increasingly reported globally, either as isolated cases or in the context of healthcare-associated outbreaks. Significant under-ascertainment of cases is likely to occur due to the limited detection and surveillance capacity in many countries.

Six genetically distinct clades of C. auris have been discovered to date, including the South Asian clade, first detected in India and Pakistan (clade I), the East Asian clade, first detected in Japan (clade II), the South African clade, first detected in South Africa (clade III), the South American clade, first detected in Venezuela (clade IV), and 2 further clades that have recently been detected in Iran (clade V) and Singapore (clade VI). Each clade is associated with certain clinical presentations, resistance patterns, and differences in virulence (12).

The literature should be consulted to identify changing areas of prevalence, including additional cases and outbreak reports.

National epidemiology

A retrospective analysis revealed that C. auris was first identified in the UK in 2013 from blood cultures in unrelated patients (13). There have since been sporadic introductions into a number of hospitals in England. Between January 2013 and December 2024 inclusive, a total of 637 C. auris isolates were reported through laboratory surveillance in England, with 59 (9.3%) isolated from blood culture specimens.

Case numbers decreased in 2020, with just 5 cases detected (all colonisations), likely a consequence of the travel restrictions associated with the COVID-19 pandemic limiting international introduction. Since 2020 cases have increased year on year; with 26 reported in 2021, 38 in 2022, 93 in 2023 and 178 in 2024 (see Figure 1). Of the 178 C. auris detections in 2024, 24 (13.5%) were invasive with 7 (3.9%) from blood culture specimens. For the latest epidemiology please refer to the most recent C. auris Health Protection Report.

Figure 1. Number of patients with first detections of C. auris in England, January 2013 to December 2024 by isolate site: bloodstream infections (BSI) and non-BSI

This data was derived by review of the UK Health Security Agency (UKHSA) SGSS and liaison with the UKHSA Mycology Reference Laboratory (MRL), NHS Mycology Reference Centre Manchester and NHS Mycology Reference Centre Leeds.

There is known under-ascertainment of C. auris cases, particularly the reporting of colonisation, and outbreak notification has frequently been subject to delay.

Subject to Parliamentary approval, from April 2025, C. auris will be listed as a notifiable causative agent under schedule 2 of the Health Protection (Notification) Regulations 2010. Laboratories that test human samples in England will be required to report C. auris cases to UKHSA, with the aim of strengthening surveillance and the public health response to this organism.

International patient transfers

Repatriation and entry to UK hospitals for medical care continues to be a source for new introductions of C. auris in England with potential to spread more widely.

Unpublished data from one UK secondary care provider that offers a screening programme to international patients (admitted directly from home or healthcare facilities) reports that of 3,404 patients screened (groin, axilla, nose) for asymptomatic C. auris carriage between January 2020 and February 2023, 56 (1.6%) screened positive. Most of these positive patients with confirmed last location (25 out of 56) were direct healthcare facility transfers from the Middle East (notably Kuwait, Qatar, and the United Arab Emirates), India and Pakistan. Eighteen out of 56 patients could not have their last known location confirmed so this may be an under representation. Patients from Kenya, Nigeria, South Africa, and France, as well as UK residents repatriated from hospitals abroad, also screened positive following admission.

C. auris outbreaks in the UK

UKHSA is aware of 5 large and protracted C. auris outbreaks which have occurred in UK hospitals between 2015 and August 2024, each comprising more than 50 cases, and which have been responsible for peaks in incidence (14 to 16). These have occurred in adult surgical critical care and surgical ward settings, including neurosurgical, cardiothoracic, and vascular units. Please refer to the latest C. auris Health Protection Report for the most recent data.

Outbreaks have been highly disruptive and costly with one study estimating total outbreak control cost in excess of £1 million over 7 months (16). Outbreaks have proved challenging to control, leading to substantial service disruption with closures of clinical areas including critical care and surgical units.

Outbreaks continue to emerge, with recent outbreaks having no identified link to healthcare abroad. However, the index case may not have been identified. Delays in outbreak detection and response, including alerting referral networks, increase the likelihood of establishment of endemicity in regions within the UK.

1. The risk assessment should consider: patient risk factors (including high-risk groups), organisation-specific factors (such as high-risk units), local and regional epidemiology, laboratory capability and capacity, IPC infrastructure, resource availability and outbreak preparedness. ↩

2. Augmented care setting is defined in Box 2 in the UKHSA Framework of actions to contain carbapenemase-producing Enterobacterales). ↩