Deadly, drug-resistant yeast infection spreading around the world

The C. auris yeast causes bloodstream infections, wound infections, and otitis (ear infections). Death can occur 30-50% of infected patients.

The most common risk factors are having an indwelling venous catheter, urinary catheter, recent surgery, previous courses of antibiotics or antifungals and prolonged hospitalization.

Summary

The Centers for Disease Control and Prevention (CDC) has received reports from international healthcare facilities that Candida auris, an emerging multidrug-resistant (MDR) yeast, is causing invasive healthcare-associated infections with high mortality. Some strains of C. auris have elevated minimum inhibitory concentrations (MICs) to the three major classes of antifungals, severely limiting treatment options. C. auris requires specialized methods for identification and could be misidentified as another yeast when relying on traditional biochemical methods. CDC is aware of one isolate of C. auris that was detected in the United States in 2013 as part of ongoing surveillance. Experience outside the United States suggests that C. auris has high potential to cause outbreaks in healthcare facilities. Given the occurrence of C. auris in nine countries on four continents since 2009, CDC is alerting U.S. healthcare facilities to be on the lookout for C. auris in patients.

Background

Candida auris is an emerging multidrug-resistant (MDR) yeast that can cause invasive infections and is associated with high mortality. It was first described in 2009 after being isolated from external ear discharge of a patient in Japan ¹. Since the 2009 report, C. auris infections, specifically fungemia, have been reported from South Korea ², India ³, South Africa ⁴, and Kuwait ⁵. Although published reports are not available, C. auris has also been identified in Colombia, Venezuela, Pakistan, and the United Kingdom.

It is unknown why C. auris has recently emerged in so many different locations. Molecular typing of strains performed by CDC suggests isolates are highly related within a country or region but highly distinct between continents ⁶. The earliest known infection with C. auris, based on retrospective testing of isolate collections, occurred in South Korea in 1996 ². C. auris may not represent a new organism so much as one that is newly emerging in various clinical settings. Although the causes for such emergence are unknown, they may include new or increasing antifungal selection pressures in humans, animals, or the environment.

C. auris infections have most commonly been hospital-acquired and occurred several weeks into a patient’s hospital stay. C. auris has been reported to cause bloodstream infections, wound infections, and otitis ². It has also been cultured from urine and the respiratory tract; however, whether isolation from these sites represented infection verses colonization in each instance is unknown. C. auris has been documented to cause infections in patients of all ages. Patients were found to have similar risk factors for infections with other Candida spp. ^{6, 7}, including: diabetes mellitus, recent surgery, recent antibiotics, and presence of central venous catheters ³. Co-infection with other Candida spp. and detection of C. auris while the patient was being treated with antifungals have also been reported ².

Although no established minimum inhibitory concentration (MIC) breakpoints exist for C. auris, resistance testing of an international collection of isolates conducted by CDC demonstrated that nearly all isolates are highly resistant to fluconazole based on breakpoints established for other Candida spp. More than half of C. auris isolates were resistant to voriconazole, one-third were resistant to amphotericin B (MIC ≥2), and a few were resistant to echinocandins. Some isolates have demonstrated elevated MICs to all three major antifungal classes, including azoles, echinocandins, and polyenes, indicating that treatment options would be limited.

C. auris phenotypically resembles Candida haemulonii ¹. Commercially available biochemical-based tests, including API strips and VITEK-2, used in many U.S. laboratories to identify fungi, cannot differentiate C. auris from related species. Because of these challenges, clinical laboratories have misidentified the organism as C. haemulonii and Saccharomyces cerevisiae. Some clinical laboratories do not fully identify all Candida to the species level, and C. auris isolates have been reported as “other Candida spp.” Clinical, state, and public health laboratories should be aware of this organism and of the limitations in its identification.

At least two countries have described healthcare outbreaks of C. auris infection and colonization involving more than 30 patients each. Analysis of isolates from these clusters demonstrate a high degree of clonality within the same hospital, supporting the idea that the organisms are being transmitted within those healthcare facilities. The precise mode of transmission within the healthcare facility is not known. However, experience during these outbreaks suggests that C. auris might contaminate the environment of rooms of colonized or infected patients. Good infection control practices and environmental cleaning may help prevent transmission.

Interim Recommendations

CDC is concerned that C. auris will emerge in new locations, including the United States. CDC and partners continue to work closely, and new information will be provided as it becomes available. CDC recommends the following actions for U.S. healthcare facilities and laboratories:

♦  Reporting — Healthcare facilities who suspect they have a patient with C. auris infection should contact state/local public health authorities and CDC (candidaauris@cdc.gov)

♦  Laboratory Diagnosis — Diagnostic devices based on matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) can differentiate C.auris, but not all devices currently include C. auris in the reference database to allow for detection. Molecular methods based on sequencing the D1-D2 region of the 28s rDNA can also identify C. auris. CDC requests that laboratories identifying C. auris isolates in the United States notify their state or local health departments and CDC (candidaauris@cdc.gov). C. haemulonii isolates and other isolates from clinical specimens that cannot be identified beyond Candida spp. by conventional methods can be forwarded through state public health laboratories to CDC for further characterization.

♦  Infection Control — Until further information is available, healthcare facilities should place patients with C. auris colonization or infection in single rooms and healthcare personnel should use Standard and Contact Precautions. In addition, state or local health authorities and CDC should be consulted about the need for additional interventions to prevent transmission. CDC is working with domestic and international partners to develop definitive infection control guidance.

♦  Environmental Cleaning – Anecdotal reports have suggested that C. auris may persist in the environment. Healthcare facilities who have patients with C. auris infection or colonization should ensure thorough daily and terminal cleaning and disinfection of these patient’s rooms using an EPA-registered hospital grade disinfectant with a fungal claim.