Candida auris – a rising global health threat

Candida auris – a rising global health threat

Over the past decade, Candida auris has emerged as a worldwide public health threat. Since its first isolation in 2009 in Japan, C. auris infections have been reported in over 30 countries. (1) Together with the increasing number of infections, this fungus is a cause of concern for three main reasons. First, C. auris easily proliferates in hospitals and has the potential to cause outbreaks in healthcare settings. Secondly, it is often resistant to multiple antifungal drugs commonly used to treat Candida infections, such as Fluconazole, and thirdly, it is often challenging to identify with standard laboratory methods.

C. auris has been isolated from various clinical specimens, including normally sterile body fluids, respiratory sections, ear canal, biliary fluid, urine, wounds and mucocutaneous swabs. Bloodstream infections (BSI) are the most commonly observed invasive infections, and, alarmingly, the mortality rates reported are in the range of 30-60%. (2) BSI are particularly dangerous in immunocompromised and critically ill patients, with the highest risk being for patients with breathing tubes, feeding tubes and central venous catheters.

Guidelines for C. auris surveillance and screening

Since 2016, the Centers for Disease Control and Prevention, the European Centre for Disease Prevention and Control and Public Health England, amongst others, has been releasing a series of alerts and guidelines to inform clinicians, laboratory scientists, and public health officials about the emerging threat posed by C. auris.

C. auris can spread in healthcare settings through contact with contaminated environmental surfaces or equipment, or from person to person, and implications of outbreaks can be dramatic (e.g., closing entire hospital departments). Therefore, surveillance and screening for C. auris colonisation are essential to implement infection prevention and control measures.

On microscopy evaluation, C. auris is indistinguishable from most other Candida species. Because of the multidrug resistance of some C. auris strains, guidelines recommend that any Candida species isolates associated with invasive infections and isolates from hospital superficial sites should be analysed to species level.

Use of C. auris-specific PCR kit in surveillance and screening

Commercially available biochemical-based tests or MALDI-TOF used in many front-line diagnostic laboratories can misidentify C. auris as a wide range of Candida species and other genera. In addition, they are time-consuming since they require culture and 24-48h incubation prior to identification.

AurisID? from OLM Diagnostics is a species-specific PCR kit approved for the detection of C. aurisfrom fungal cultures and directly from blood samples, with a previous step of nucleic extraction. A recent paper by Bayona and colleagues validated AurisID? kit for direct detection of C. aurisfrom clinical surveillance samples without the DNA extraction step, to reduce the turnaround time even further. (3) When compared to the routine protocol, the PCR method showed 96.6% sensitivity, 100% specificity, 100% positive predictive value and 98.2% negative predictive value, with a significant reduction in the time-to-result (45 minutes vs >24-48h). For a nosocomial pathogen like C. auris, a faster and more streamlined surveillance of colonisation is needed to enhance control measures and prevent hospital outbreaks and as shown by the recently published data, AurisID? is an effective tool to do so.

For more information, please contact our Scientific Director, Dr Gemma Johnson, on [email protected] ?