Resistance to echinocandin antifungal agents in the United Kingdom in clinical isolates of Candida glabrata: Fifteen years of interpretation and assessment.

Candidemia is widely reported as the fourth most common form of bloodstream infection worldwide. Reports of breakthrough cases of candidemia are increasing, especially in the context of a move away from azole antifungals as prophylactic or first line treatment toward the use of echinocandin agents. The global evaluation of echinocandin antifungal susceptibility since 2003 has included switches in testing methodologies and the move to a sentinel echinocandin approach for classification reporting. This study compiles previously unpublished data from echinocandin susceptibility testing of UK clinical isolates of C. glabrata received at the Public Health England Mycology Reference Laboratory from 2003 to 2016 and reevaluates the prevalence of resistance in light of currently accepted testing protocols. From 2015 onward, FKS gene mutation detection using a novel Pyrosequencing® assay was assessed as a predictor of echinocandin resistance alongside conventional susceptibility testing. Overall, our data show that echinocandin resistance in UK isolates of C. glabrata is a rare phenomenon and prevalence has not appreciably increased in the last 14 years. The pyrosequencing assay was able to successfully detect hot spot mutations in FKS1 and FKS2, although not all isolates that exhibited phenotypic resistance demonstrated detectable hot spot mutations. We propose that a rapid genomic based detection method for FKS mutations, as part of a multifactorial approach to susceptibility testing, could help provide accurate and timely management decisions especially in regions where echinocandin resistance has been reported to be emerging in this important pathogen.

Candida auris outbreak: Mortality, interventions and cost of sustaining control.

OBJECTIVE: Candida auris has recently emerged as a global cause of multidrug resistant fungal outbreaks. An outbreak occurred at a tertiary care center in London in 2016. Transmission characteristics, interventions, patient outcomes and cost of resources are described. METHODS: Outbreak interventions included patient isolation, contact screening, single-use equipment, environmental screening and decontamination, staff education, and enhanced surveillance. Risk factors for infection were recorded. Survival probabilities of patients with C. auris and other Candida bloodstream infections (BSI) were calculated. Antifungal susceptibility and epidemiological typing were performed. Actual and opportunity costs of interventions were determined. RESULTS: 34 patients acquired the organism including 8 with BSI. Clinical infection was significantly associated with prolonged hospital stay, haemodialysis and antifungal therapy. Variable susceptibility to amphotericin and the triazoles was seen and isolates clustered with the South Asian strains. No significant difference was detected in the survival probabilities of C. auris BSI compared to other candidemias. Outbreak control cost in excess of £1 million and £58,000/month during the subsequent year. CONCLUSION: C. auris outbreaks can be controlled by a concerted infection control strategy but can be expensive. Transmission maybe prolonged due to patient movements and unidentified transmission mechanisms.

Assessment of accuracy of identification of pathogenic yeasts in microbiology laboratories in the United kingdom.

Rapid, accurate identification of yeast isolates from clinical samples has always been important given their innately variable antifungal susceptibility profiles. Recently, this has become paramount with the proposed introduction of species-specific interpretive breakpoints for MICs obtained in yeast antifungal susceptibility tests (M. A. Pfaller, D. Andes, D. J. Diekema, A. Espinel-Ingroff, D. Sheehan, and CLSI Subcommittee for Antifungal Susceptibility Testing, Drug Resist. Updat. 13:180-195, 2010). Here, we present the results of a 12-month evaluation of the accuracy of identifications that accompany yeast isolates submitted to the Mycology Reference Laboratory (United Kingdom) for either confirmation of identity or susceptibility testing. In total, 1,781 yeast isolates were analyzed, and the robustness of prior identifications obtained in microbiology laboratories throughout the United Kingdom was assessed using a combination of culture on chromogenic agar, morphology on cornmeal agar, and molecular identification by pyrosequencing. Over 40% of isolates (755) were submitted without any suggested identification. Of those isolates with a prior identification, 100 (9.7%) were incorrectly identified. Error rates ranged from 5.2% (for organisms submitted for antifungal susceptibility testing) to 18.2% (for organisms requiring confirmation of identity) and varied in a strictly species-specific manner. At least 50% of identification errors would be likely to affect interpretation of MIC data, with a possible impact on patient management. In addition, 2.3% of submitted cultures were found to contain mixtures of at least two yeast species. The vast majority of mixtures had gone undetected in the referring laboratory and would have impacted the interpretation of antifungal susceptibility profiles and patient management. Some of the more common misidentifications are discussed according to the identification method employed, with suggestions for avoiding such misinterpretations.

An improved protocol for the preparation of total genomic DNA from isolates of yeast and mould using Whatman FTA filter papers.

Here, we present a significantly improved version of our previously published method for the extraction of fungal genomic DNA from pure cultures using Whatman FTA filter paper matrix technology. This modified protocol is extremely rapid, significantly more cost effective than our original method, and importantly, substantially reduces the problem of potential cross-contamination between sequential filters when employing FTA technology.