Validation and implementation of a commercial real-time PCR assay for direct detection of Candida auris from surveillance samples.

BACKGROUND: Rapid and reliable laboratory methods are required for detecting the nosocomial yeast Candida auris. AurisID® (Olm Diagnostics) is a real-time PCR assay approved for detecting C. auris in fungal cultures and directly from blood samples, involving a nucleic acid extraction as a prior step. OBJECTIVES: The purpose of this study is to validate the AurisID® kit for direct detection of C. auris from surveillance samples without prior DNA extraction and to analyse the results of implementing this methodology to our daily laboratory routine protocol for C. auris surveillance studies. METHODS: Our PCR method using the AurisID® kit was compared with our routine protocol, consisting of culture in CHROMagar® Candida and identification by mass spectrometry. A total of 113 swabs were used for validation and 136 pair of surveillance samples were tested. Limit of detection (LOD) was determined by using swabs in Amies transport medium, which were spiked in a series of dilutions of a C. auris standardised suspension (0.5 McFarland). RESULTS: The PCR method showed high sensitivity, specificity, predictive positive value and predictive negative value (96.6%, 100%, 100% and 98.2%, respectively) when compared with the routine protocol. LOD was 500 CFU/ml, which corresponds to approximately 1 CFU/PCR. CONCLUSIONS: Our PCR method using the AurisID® kit allows a reduction in the turnaround time for surveillance of C. auris compared with other methods. These results are expected to contribute to control C. auris outbreaks, allowing isolation of patients and cleaning of environmental surfaces in advance.

Characteristics and Management of Candidaemia Episodes in an Established Candida auris Outbreak.

The multi-resistant yeast Candida auris has become a global public health threat because of its ease to persist and spread in clinical environments, especially in intensive care units. One of the most severe manifestations of invasive candidiasis is candidaemia, whose epidemiology has evolved to more resistant non-albicansCandida species, such as C. auris. It is crucial to establish infection control policies in order to control an outbreak due to nosocomial pathogens, including the implementation of screening colonisation studies. We describe here our experience in managing a C. auris outbreak lasting more than two and a half years which, despite our efforts in establishing control measures and surveillance, is still ongoing. A total of 287 colonised patients and 47 blood stream infections (candidaemia) have been detected to date. The epidemiology of those patients with candidaemia and the susceptibility of C. auris isolates are also reported. Thirty-five patients with candidaemia (74.5%) were also previously colonised. Forty-three patients (91.5%) were hospitalised (61.7%) or had been hospitalised (29.8%) in the ICU before developing candidaemia. Antifungal therapy for candidaemia consisted of echinocandins in monotherapy or in combination with amphotericin B or isavuconazole. The most common underlying disease was abdominal surgery (29.8%). The thirty-day mortality rate was 23.4% and two cases of endophtalmitis due to C. auris were found. All isolates were resistant to fluconazole and susceptible to echinocandins and amphotericin B. One isolate became resistant to echinocandins two months after the first isolate. Although there are no established clinical breakpoints, minimum inhibitory concentrations for isavuconazole were low (≤ 1 µg/mL).

Evaluation of a novel chromogenic medium for Candida spp. identification and comparison with CHROMagar™ Candida for the detection of Candida auris in surveillance samples.

A shift to Candida non-albicans infections has been noted during the last years, and the emergence of multi-resistant Candida auris has complicated their management. The aim of this study was first to compare the performance of the novel chromogenic medium CHROMagar™ Candida Plus (CHROMagar, France) with CHROMagar™ Candida (Becton Dickinson, Germany) for the presumptive identification of Candida species; and then, to evaluate its utility in the detection of C. auris in surveillance samples. CHROMagar™ Candida Plus showed a good performance compared with the reference medium CHROMagar™ Candida. Sensitivity and specificity were 100% in both media for tested species at 48 h of incubation, except for Candida glabrata and Candida lusitaniae. Furthermore, the new medium allows a reliable presumptive identification of C. auris, as a new specific color for this species is assigned (light blue with a blue halo), obtaining a sensitivity and specificity of 100% at 36 h of incubation.