Neosartorya udagawae pulmonary infection requiring a surgical treatment in a paediatric haematopoietic progenitor cell recipient

Neosartorya udagawae is a known cause of fungal infection in humans and animals. It is found to be more refractory to antifungal treatment in comparison to other Aspergillus species. With this report we present a case of proven invasive infection with Neosartorya udagawae in a child with chronic myeloid leukaemia after haematopoietic stem cell transplant. The patient received several lines of antifungal therapy including dual therapy appropriate to the antifungal susceptibility profile with progression of the invasive fungal disease requiring left lung upper lobe lobectomy. The case emphasizes the importance of early biopsy with antifungal susceptibility testing for targeted therapy and demonstrates the potential requirement for surgical management in addition to appropriate antifungal treatment.

Terbinafine-resistant Trichophyton indotineae causing extensive dermatophytosis in a returning traveller, London, UK

Severe and antifungal-resistant dermatophyte infections are a growing global public health concern. Trichophyton indotineae, a novel dermatophyte species, has caused an epidemic of severe, difficult-to-treat and recalcitrant dermatophytoses in India and South Asia, where it is now common. We present a case of terbinafine-resistant T. indotineae in London, UK, causing extensive dermatophytosis associated with recent travel to Latin America, outside the previously reported risk area.

The laboratory investigation, management, and infection prevention and control of Candida auris: a narrative review to inform the 2024 national guidance update in England

The emergent fungal pathogen Candida auris is increasingly recognised as an important cause of healthcare-associated infections globally. It is highly transmissible, adaptable, and persistent, resulting in an organism with significant outbreak potential that risks devastating consequences. Progress in the ability to identify C. auris in clinical specimens is encouraging, but laboratory diagnostic capacity and surveillance systems are lacking in many countries. Intrinsic resistance to commonly used antifungals, combined with the ability to rapidly acquire resistance to therapy, substantially restricts treatment options and novel agents are desperately needed. Despite this, outbreaks can be interrupted, and mortality avoided or minimised, through the application of rigorous infection prevention and control measures with an increasing evidence base. This review provides an update on epidemiology, the impact of the COVID-19 pandemic, risk factors, identification and typing, resistance profiles, treatment, detection of colonisation, and infection prevention and control measures for C. auris. This review has informed a planned 2024 update to the United Kingdom Health Security Agency (UKHSA) guidance on the laboratory investigation, management, and infection prevention and control of Candida auris. A multidisciplinary response is needed to control C. auris transmission in a healthcare setting and should emphasise outbreak preparedness and response, rapid contact tracing and isolation or cohorting of patients and staff, strict hand hygiene and other infection prevention and control measures, dedicated or single-use equipment, appropriate disinfection, and effective communication concerning patient transfers and discharge.

The yeast genus Tardiomyces gen. nov. with one new species and two new combinations

PURPOSE

Rare yeasts species are increasingly reported as causative agents of invasive human infection. Proper identification and antifungal therapy are essential to manage these infections. Candida blankii is one of these emerging pathogens and is known for its reduced susceptibility to multiple antifungals.

METHODS

To obtain more insight into the characteristics of this species, 26 isolates reported as C. blankii were investigated using genetic and phenotypical approaches.

RESULTS

Among the 26 isolates, seven recovered either from blood, sputum, urine, or the oral cavity, displayed substantial genetic and some phenotypical differences compared to the other isolates, which were confirmed as C. blankii. We consider these seven strains to represent a novel species, Tardiomyces depauwii. Phylogenomics assigned C. blankii, C. digboiensis, and the novel species in a distinct branch within the order Dipodascales, for which the novel genus Tardiomyces is erected. The new combinations Tardiomyces blankii and Tardiomyces digboiensis are introduced. Differences with related, strictly environmental genera Sugiyamaella, Crinitomyces, and Diddensiella are enumerated. All three Tardiomyces species share the rare ability to grow up to 42 °C, display slower growth in nutrient-poor media, and show a reduced susceptibility to azoles and echinocandins. Characteristics of T. depauwii include high MIC values with voriconazole and a unique protein pattern.

CONCLUSION

We propose the novel yeast species Tardiomyces depauwii and the transfer of C. blankii and C. digboiensis to the novel Tardiomyces genus.

Comparative transcriptional analysis of Candida auris biofilms following farnesol and tyrosol treatment

Candida auris is frequently associated with biofilm-related invasive infections. The resistant profile of these biofilms necessitates innovative therapeutic options, where quorum sensing may be a potential target. Farnesol and tyrosol are two fungal quorum-sensing molecules with antifungal effects at supraphysiological concentrations. Here, we performed genome-wide transcript profiling with C. auris biofilms following farnesol or tyrosol exposure using transcriptome sequencing (RNA-Seq). Since transition metals play a central role in fungal virulence and biofilm formation, levels of intracellular calcium, magnesium, and iron were determined following farnesol or tyrosol treatment using inductively coupled plasma optical emission spectrometry. Farnesol caused an 89.9% and 73.8% significant reduction in the calcium and magnesium content, respectively, whereas tyrosol resulted in 82.6%, 76.6%, and 81.2% decrease in the calcium, magnesium, and iron content, respectively, compared to the control. Genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy were primarily affected in treated cells. To prove ergosterol quorum-sensing molecule interactions, microdilution-based susceptibility testing was performed, where the complexation of farnesol, but not tyrosol, with ergosterol was impeded in the presence of exogenous ergosterol, resulting in a minimum inhibitory concentration increase in the quorum-sensing molecules. This study revealed several farnesol- and tyrosol-specific responses, which will contribute to the development of alternative therapies against C. auris biofilms.

IMPORTANCE

Candida auris is a multidrug-resistant fungal pathogen, which is frequently associated with biofilm-related infections. Candida-derived quorum-sensing molecules (farnesol and tyrosol) play a pivotal role in the regulation of fungal morphogenesis and biofilm development. Furthermore, they may have remarkable anti-biofilm effects, especially at supraphysiological concentrations. Innovative therapeutic approaches interfering with quorum sensing may be a promising future strategy against C. auris biofilms; however, limited data are currently available concerning farnesol-induced and tyrosol-related molecular effects in C. auris. Here, we detected several genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy, which were primarily influenced following farnesol or tyrosol exposure. Moreover, calcium, magnesium, and iron homeostasis were also significantly affected. These results reveal those molecular and physiological events, which may support the development of novel therapeutic approaches against C. auris biofilms.

Antifungal susceptibility profiles for fungal isolates from corneas and contact lenses in the United Kingdom

OBJECTIVE

To report the identification and results of susceptibility testing for fungal isolates from the cornea or contact lens care systems.

MATERIALS AND METHODS

In this retrospective epidemiological study, we searched the results of fungal cultures from cornea or contact lens systems referred for identification and susceptibility testing to the United Kingdom National Mycology Reference Laboratory between October 2016 and March 2022. For each fungal isolate, we recorded the genus and species of the fungus and the minimum inhibitory concentration (MIC) to six antifungal agents available to treat corneal infection (amphotericin, econazole, itraconazole, natamycin, posaconazole, and voriconazole).

RESULTS

There were 600 isolates from 585 patients, comprising 374 (62%) from corneal samples and 226 from contact lenses and care systems, of which 414 (69%) isolates were moulds (filamentous fungi) and 186 (31%) were yeasts. The most frequent moulds isolated were Fusarium spp (234 isolates, 39%) and Aspergillus spp (62, 10%). The most frequent yeasts isolated were Candida spp (112, 19%), predominantly Candida parapsilosis (65, 11%) and Candida albicans (33, 6%), with 35 isolates (6%) of Meyerozyma guilliermondii. In vitro susceptibility was greatest for natamycin (347 moulds tested, mode 4 mg/L, range 0.25-64 mg/L; 98 yeasts tested, mode 4 mg/L, range 0.5-32 mg/L), with susceptibility for 94% for moulds and 99% yeasts. Of the 16 isolates interpreted as highly resistant to natamycin (MIC ≥16 mg/L), 13 were Aspergillus flavus complex.

CONCLUSIONS

In vitro susceptibility supports the use of natamycin for the empiric treatment of fungal keratitis in the UK.

Pulmonary endemic mycoses

While rare, the likelihood of encountering a case of a pulmonary endemic mycosis (PEM) in the UK is increasing. Diagnosis may be challenging, often leading to considerable delay to appropriate treatment. Clinical suspicion must be present for respiratory disease, particularly in the immunocompromised or in those not responding to empiric treatment approaches, and an extended travel history should be obtained. This article summarises the epidemiology of PEM, key clinical features, diagnostic strategies and management.

Changes in fungal taxonomy: mycological rationale and clinical implications

Numerous fungal species of medical importance have been recently subjected to and will likely continue to undergo nomenclatural changes as a result of the application of molecular approaches to fungal classification together with abandonment of dual nomenclature. Here, we summarize those changes affecting key groups of fungi of medical importance, explaining the mycological (taxonomic) rationale that underpinned the changes and the clinical relevance/importance (where such exists) of the key nomenclatural revisions. Potential mechanisms to mitigate unnecessary taxonomic instability are suggested, together with approaches to raise awareness of important changes to minimize potential clinical confusion.

Strain and temperature dependent aggregation of Candida auris is attenuated by inhibition of surface amyloid proteins

Candida auris is a multi-drug resistant human fungal pathogen that has become a global threat to human health due to its drug resistant phenotype, persistence in the hospital environment and propensity for patient to patient spread. Isolates display variable aggregation that may affect the relative virulence of strains. Therefore, dissection of this phenotype has gained substantial interest in recent years. We studied eight clinical isolates from four different clades (I-IV); four of which had a strongly aggregating phenotype and four of which did not. Genome analysis identified polymorphisms associated with loss of cell surface proteins were enriched in weakly-aggregating strains. Additionally, we identified down-regulation of chitin synthase genes involved in the synthesis of the chitinous septum. Characterisation of the cells revealed no ultrastructural defects in cytokinesis or cell separation in aggregating isolates. Strongly and weakly aggregating strains did not differ in net surface charge or in cell surface hydrophobicity. The capacity for aggregation and for adhesion to polystyrene microspheres were also not correlated. However, aggregation and extracellular matrix formation were all increased at higher growth temperatures, and treatment with the amyloid protein inhibitor Thioflavin-T markedly attenuated aggregation. Genome analysis further indicated strain specific differences in the genome content of GPI-anchored proteins including those encoding genes with the potential to form amyloid proteins. Collectively our data suggests that aggregation is a complex strain and temperature dependent phenomenon that may be linked in part to the ability to form extracellular matrix and cell surface amyloids.

Total transcriptome analysis of Candida auris planktonic cells exposed to tyrosol

Tyrosol, a secondary metabolite of Candida species, regulates fungal morphogenesis, and its application may represent a novel innovative therapy against emerging multi-resistant fungal superbug such as Candida auris. In the current study, the effects of tyrosol on growth, redox homeostasis, intracellular microelement contents and activities of virulence-related enzymes released by C. auris were examined. To gain further information about the effect of tyrosol exposure, we revealed gene transcriptional changes using total transcriptome sequencing (RNA-Seq). At a concentration of 15 mM, tyrosol significantly decrease the growth of fungal cells within 2 h of its addition (5.6 × 107±1.2 × 107 and 2.5 × 107±0.6 × 107 colony forming unit/mL for control and tyrosol-treated cells, respectively). Furthermore, it enhanced the release of reactive oxygen species as confirmed by a dichlorofluorescein (DCF) assay (7.3 ± 1.8 [nmol DCF (OD640)-1] versus 16.8 ± 3.9 [nmol DCF (OD640)-1]), which was coincided with elevated superoxide dismutase, catalase and glutathione peroxidase activities. Tyrosol exerted in a 37%, 25%, 34% and 55% decrease in intracellular manganese, iron, zinc and copper contents, respectively, compared to control cells. The tyrosol treatment led to a 142 and 108 differentially transcripted genes with at least a 1.5-fold increase or decrease in transcription, respectively. Genes related to iron and fatty acid metabolism as well as nucleic acid synthesis were down-regulated, whereas those related to the antioxidative defence, adhesion and oxoacid metabolic processes were up-regulated. This study shows that tyrosol significantly influences growth, intracellular physiological processes and gene transcription in C. auris, which could highly support the development of novel treatment approaches against this important pathogen.

Citizen science reveals landscape-scale exposures to multiazole-resistant Aspergillus fumigatus bioaerosols

Using a citizen science approach, we identify a country-wide exposure to aerosolized spores of a human fungal pathogen, Aspergillus fumigatus, that has acquired resistance to the agricultural fungicide tebuconazole and first-line azole clinical antifungal drugs. Genomic analysis shows no distinction between resistant genotypes found in the environment and in patients, indicating that at least 40% of azole-resistant A. fumigatus infections are acquired from environmental exposures. Hotspots and coldspots of aerosolized azole-resistant spores were not stable between seasonal sampling periods. This suggests a high degree of atmospheric mixing resulting in an estimated per capita cumulative annual exposure of 21 days (±2.6). Because of the ubiquity of this measured exposure, it is imperative that we determine sources of azole-resistant A. fumigatus to reduce treatment failure in patients with aspergillosis.

Name Changes for Fungi of Medical Importance, 2020 to 2021

The current article summarizes recent changes in nomenclature for fungi of medical importance published in the years 2020 to 2021, including new species and revised names for existing ones. Many of the revised names have been widely adopted without further discussion. However, those that concern common pathogens of humans may take longer to achieve general usage, with new and current names reported together to engender increasing familiarity with the correct taxonomic classification.

In Vitro Killing Activities of Anidulafungin and Micafungin with and without Nikkomycin Z against Four Candida auris Clades

Candida auris is a multidrug-resistant pathogen against which echinocandins are the drug of choice. However, information on how the chitin synthase inhibitor nikkomycin Z influences the killing activities of echinocandins against C. auris is currently lacking. We determined the killing activities of anidulafungin and micafungin (0.25, 1, 8, 16 and 32 mg/L each) with and without nikkomycin Z (8 mg/L) against 15 isolates representing four C. auris clades (South Asian n = 5; East Asian n = 3; South African n = 3; South American n = 4, two of which were of environmental origin). Two and one isolates from the South Asian clade harbored mutations in the hot-spot 1 (S639Y and S639P) and 2 (R1354H) regions of the FKS1 gene, respectively. The anidulafungin, micafungin and nikkomycin Z MIC ranges were 0.015-4, 0.03-4 and 2->16 mg/L, respectively. Anidulafungin and micafungin alone exerted weak fungistatic activity against wild-type isolates and the isolate with a mutation in the hot-spot 2 region of FKS1 but was ineffective against the isolates with a mutation in the hot-spot 1 region. The nikkomycin Z killing curves were always similar to their respective controls. Twenty-two of sixty (36.7%) anidulafungin plus nikkomycin Z and twenty-four of sixty (40%) micafungin plus nikkomycin Z combinations produced at least 100-fold decreases in the CFUs (synergy), with a 41.7% and 20% fungicidal effect, respectively, against wild-type isolates. Antagonism was never observed. Similar results were found with the isolate with a mutation in hot-spot 2 of FKS1, but the combinations were ineffective against the two isolates with prominent mutations in hot-spot 1 of FKS1. The simultaneous inhibition of β-1,3 glucan and chitin synthases in wild-type C. auris isolates produced significantly greater killing rates than either drug alone. Further studies are warranted to verify the clinical efficacy of echinocandin plus nikkomycin Z combinations against echinocandin susceptible C. auris isolates.

The first three reported cases of Sporothrix brasiliensis cat-transmitted sporotrichosis outside South America

An epidemic of cat-transmitted sporotrichosis caused by Sporothrix brasiliensis has emerged as a major public health threat in Brazil in recent decades. We report the first three cases of cat-transmitted sporotrichosis caused by Sporothrix brasiliensis outside South America, and the first ever cases of cat-transmitted sporotrichosis in the United Kingdom. We outline the public health implications and outbreak response and encourage clinicians and veterinarians worldwide to be vigilant for sporotrichosis in cats and cat owners.

The importance of appropriate processing and direct microscopic examination for the timely diagnosis and management of invasive infections caused by filamentous fungi

The gold standard for diagnosis of invasive fungal infections caused by filamentous fungi remains the visualization of fungal elements in fluids, and biopsy/tissue collected from a normally sterile body site. Parallel recovery of viable fungus from the sample subsequently permits antifungal susceptibility testing of the individual isolate. Central to both processes is the appropriate processing of tissue specimens to avoid damaging fungal elements and optimize viable organism recovery. Historically, mycologists have proposed that homogenization (grinding or bead-beating) of tissue should be avoided in cases of suspected fungal infection as it likely damages hyphae, instead preferring to chop tissue into small portions (dicing) for direct microscopic examination and culture. Here, we have compared the two processes directly on material from clinical patient cases of mucoromycosis and invasive aspergillosis. Representative portions of fresh biopsy samples were processed in parallel either by chopping (dicing) in the mycology reference laboratory or by bead-beating in the adjoining general microbiology laboratory. Aliquots of the samples were then cultured under identical conditions and subjected to direct microscopic examination. The results demonstrated that tissue homogenization significantly reduced (i) organism recovery rates in cases of both mucoromycosis and invasive aspergillosis and (ii) the number of fungal elements detectable upon direct microscopic examination. To our knowledge, this is the first study to directly compare these alternative processing methods and despite only employing a limited number of samples the data presented here, provide support for the perceived mycological wisdom that homogenization of tissue samples should be avoided when filamentous fungal infections are suspected.

Disseminated Bisifusarium infection following toxic epidermal necrolysis in a child with B-cell acute lymphoblastic leukemia

Fusarium is a polyphyletic genus of plant pathogens, members of which can cause opportunistic human infections with varying superficial and systemic presentations, including disseminated infections which typically occur in immunocompromised patients and have a poor prognosis. Treatment is challenging due to intrinsic resistance to many antifungal agents, and antifungal susceptibility testing is therefore essential. Early suspicion, isolation of the organism, and prompt initiation of management are crucial to improving survival. We present a case of disseminated Bisifusarium infection following toxic epidermal necrolysis in a child with B-cell acute lymphoblastic leukemia, successfully treated with liposomal amphotericin B, voriconazole, flucytosine, and terbinafine.

First experience of implementing Candida auris real-time PCR for surveillance in the UK: detection of multiple introductions with two international clades and improved patient outcomes

BACKGROUND

Candida auris has been associated with rapid transmission and high mortality. A novel PCR-based surveillance programme was initiated at a London teaching hospital from January 2018. The results of this implementation until March 2019 are presented along with the clinical, transmission and phylogenetic characteristics encountered in that setting.

METHODS

A real-time PCR assay for C. auris was developed, validated, and implemented for direct use on skin swabs and urine. Environmental swabs were also tested by PCR as an emergency outbreak-control measure. Clinical risk factors and outcomes of patients were determined. Environmental dispersal was assessed using 24 h settle plate cultures around nine colonized patients followed by air sampling around one colonized patient during high- and low-turbulence activities. Sequencing was performed using Illumina HiSeq and maximum likelihood phylogenies were constructed using rapid bootstrap analysis.

RESULTS

Twenty-one C. auris colonized patients were identified. Median turnaround time of colonization detection reduced from 141 h (5.8 days) to approximately 24 h enabling rapid infection-control precautions. Settle plates detected 70-600 cfu/m² around colonized patients over 24 h and air sampling suggested dispersal during turbulent activities. C. auris DNA was detected from 35.7% environmental swabs. Despite being in a high-risk setting, no patients developed invasive infection. Sequencing analysis of isolates from this centre identified two introductions of the South Asian (Clade I) and one of the South African (Clade III) strain.

CONCLUSION

The PCR offers a rapid, scalable method of screening and supports clinical risk reduction in settings likely to encounter multiple introductions.

Drug repurposing against Candida auris: A systematic review

Candida auris is a drug-resistant pathogen with several reported outbreaks. The treatment of C. auris infections is difficult due to a limited number of available antifungal drugs. Thus, finding alternative drugs through repurposing approaches would be clinically beneficial. A systematic search in PubMed, Scopus and Web of Science databases, as well as Google Scholar up to 1 November 2021, was conducted to find all articles with data regarding the antifungal activity of non-antifungal drugs against the planktonic and biofilm forms of C. auris. During database and hand searching, 290 articles were found, of which 13 were eligible for inclusion in the present study. Planktonic and biofilm forms have been studied in 11 and 8 articles (with both forms examined in 6 articles), respectively. In total, 22 and 12 drugs/compounds have been reported as repositionable against planktonic and biofilm forms of C. auris, respectively. Antiparasitic drugs, with the dominance of miltefosine, were the most common repurposed drugs against both forms of C. auris, followed by anticancer drugs (e.g. alexidine dihydrochloride) against the planktonic form and anti-inflammatory drugs (e.g. ebselen) against the biofilm form of the fungus. A collection of other drugs from various classes have also shown promising activity against C. auris. Following drug repurposing approaches, a number of drugs/compounds from various classes have been found to inhibit the planktonic and biofilm forms of C. auris. Accordingly, drug repurposing is an encouraging approach for discovering potential alternatives to conventional antifungal agents to combat drug resistance in fungi, especially C. auris.

In Vivo Efficacy of Amphotericin B against Four Candida auris Clades

Candida auris is a multidrug-resistant fungus against which in some clinical situations amphotericin B (AMB) remains the alternative or first line drug. We compared daily 1 mg/kg of AMB efficacy in a neutropenic murine bloodstream infection model against 10 isolates representing four C. auris clades (South Asian n = 2; East Asian n = 2; South African n = 2; South American n = 4; two of which were of environmental origin). Five days of AMB treatment significantly increased the survival rates in mice infected with isolates of the East Asian clade, and 1 isolate each from the South African and South American clades (originated from bloodstream), but not in mice infected with the South Asian and 2 environmental isolates from the South American clades. AMB treatment decreased the fungal burden in mice infected with the 2 isolates each from East Asian and South African, and 1 out of 2 bloodstream isolates from South American clades in the hearts (p < 0.01), kidneys (p < 0.01) and brain (p < 0.05). AMB treatment, regardless of clades, significantly decreased colony forming units in the urine at day 3. However, histopathological examination in AMB-treated mice revealed large aggregates of yeast cells in the kidneys and hearts, and focal lesions in the cerebra and cerebelli, regardless of precise C. auris clade. Our clade-specific data confirm that the efficacy of AMB against C. auris is weak, explaining the therapeutic failures in clinical situations. Our results draw attention to the necessity to maximize the killing at the start of treatment to avoid later complications in the heart and central nervous system.

Susceptibility Testing of Candida auris Isolates

Susceptibility testing of isolates of Candida auris is helpful as a guide to the selection of the most appropriate antifungal agent for treatment as different clades and strains within clades often demonstrate markedly different susceptibility profiles. Some strains are relatively susceptible to all antifungal drugs, but most demonstrate innate resistance to fluconazole, many are cross-resistant to other azoles and others demonstrate resistance to other classes of antifungal. The finding of multi-drug resistance, where an isolate is resistant to two or more classes of antifungal agent, is not uncommon, and development of resistance during a course of treatment has also been documented. This chapter describes a reference broth microdilution method for susceptibility testing and a commercially available gradient strip method.

The Use of Galleria mellonella Larvae to Study the Pathogenicity and Clonal Lineage-Specific Behaviors of the Emerging Fungal Pathogen Candida auris

Candida species are the most common fungal causes of disseminated infections in humans. Although such infections are associated with high morbidity and mortality, it is widely accepted that virulence, antifungal susceptibility, and disease outcome vary according to individual Candida species. In this respect, the emerging pathogen Candida auris has received much attention due to its propensity to cause widespread nosocomial outbreaks, to exhibit high virulence in several infection models, and to develop resistance to multiple classes of antifungal drugs. Although mammalian models of infection have long been viewed as the gold standard for studies on fungal virulence, comparative pathogenicity, and evaluation of antifungal drug efficacy, the larvae of the greater wax moth Galleria mellonella have shown considerable promise as an alternative invertebrate model of infection. Galleria larvae are inexpensive, are easily maintained in the laboratory, tolerate incubation at human physiological temperatures, possess cellular and humoral immune systems that share many features with mammals, and allow investigation of pathogenicity/virulence using multiple different reading endpoints. Here, I describe in detail the methods that can be used to study the virulence/pathogenicity of Candida auris in G. mellonella.

The considerable impact of the SARS-CoV-2 pandemic and COVID-19 on the UK National Mycology Reference Laboratory activities and workload

Starting late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating global pandemic of coronavirus-19 disease (COVID-19) with ∼179 million cases and ∼3.9 million deaths to date. COVID-19 ranges from asymptomatic infection to severe illness with acute respiratory distress requiring critical care in up to 40% of hospitalized patients. Numerous reports have identified COVID-19-associated pulmonary aspergillosis (CAPA) as an important infective complication of COVID-19. In the UK, the pandemic has had unprecedented impacts on the National Health Service (NHS'): each wave of infections required hospitals to reconfigure for large surges in patients requiring intensive care, to the detriment of most aspects of non-COVID care including planned operations, outpatient appointments, general practitioner consultations and referrals. The UK National Mycology Reference Laboratory (MRL) offers a comprehensive service for the diagnosis and management of fungal disease nationwide, with a test portfolio that includes: diagnosis of allergies to fungal and other respiratory allergens; diagnosis of superficial and invasive/systemic fungal infections using traditional mycological, serological and molecular approaches; identification and susceptibility testing of the causative fungi; therapeutic drug monitoring of patients receiving antifungal therapy. Here, we describe the impact of the first 14 months of the COVID-19 pandemic on MRL activities. Changes to MRL workload closely mirrored many of the NHS-wide challenges, with marked reductions in 'elective' mycological activities unrelated to the pandemic and dramatic surges in tests that contributed to the diagnosis and management of COVID-19-related secondary fungal infections, in particular CAPA and candidemia in COVID-19 patients in intensive care.

LAY SUMMARY

The COVID-19 pandemic has had an unprecedented impact on the UK National Health Service, with hospitals forced to repeatedly reconfigure to prepare for large surges in COVID-19 patients. Here we describe the impact of the first 14 months of the UK pandemic on the workload of the National Mycology Reference Laboratory.

CHROMagarTM Candida Plus: A novel chromogenic agar that permits the rapid identification of Candida auris

Candida auris is a serious nosocomial health risk, with widespread outbreaks in hospitals worldwide. Successful management of such outbreaks has depended upon intensive screening of patients to identify those that are colonized and the subsequent isolation or cohorting of affected patients to prevent onward transmission. Here we describe the evaluation of a novel chromogenic agar, CHROMagarTM Candida Plus, for the specific identification of Candida auris isolates from patient samples. Candida auris colonies on CHROMagarTM Candida Plus are pale cream with a distinctive blue halo that diffuses into the surrounding agar. Of over 50 different species of Candida and related genera that were cultured in parallel, only the vanishingly rare species Candida diddensiae gave a similar appearance. Moreover, both the rate of growth and number of colonies of C. auris recovered from swabs of pure and mixed Candida species were substantially increased on CHROMagarTM Candida Plus agar when compared with growth on the traditional mycological isolation medium, Sabouraud dextrose agar. Taken together, the present data suggest that CHROMagarTM Candida Plus agar is an excellent alternative to current conventional mycological media for the screening of patients who are potentially colonized/infected with Candida auris, can be reliably used to identify this emerging fungal pathogen, and should be tested in a clinical setting.

LAY ABSTRACT

Candida auris is a novel pathogenic yeast that has been associated with large hospital outbreaks across several continents. Affected patients become colonized, predominantly on the skin, with large quantities of C. auris which they then shed into the hospital environment. Identification of C. auris is challenging using routine laboratory methods, and time consuming when patients are colonized with a mixture of different Candida species. Here we demonstrate that a novel chromogenic agar, CHROMagarTM Candida Plus, permits the rapid differentiation of C. auris from a wide range of other yeast species and is potentially ideally suited to screening of patients that are suspected of being colonized or infected with this medically important yeast.

Unpredictable In Vitro Killing Activity of Amphotericin B against Four Candida auris Clades

Candida auris is an emerging multiresistant yeast against which amphotericin B (AMB) is still the first therapeutic choice in certain clinical situations (i.e., meningitis, endophthalmitis, and urinary tract infections). As data about the in vitro killing activity of AMB against C. auris clades are lacking, we determined MICs, minimum fungicidal concentrations (MFCs), and killing activity of AMB against 22 isolates representing the 4 major C. auris clades (South Asian n = 6; East Asian n = 4; South African n = 6, and South American n = 6). MIC values were ≤1 mg/L regardless of clades; MFC ranges were, 1–4 mg/L, 2–4 mg/L, 2 mg/L, and 2–8 mg/L for South Asian, East Asian, South African, and South American clades, respectively. AMB showed concentration-, clade-, and isolate-dependent killing activity. AMB was fungicidal at 1 mg/L against two of six, two of four, three of six, and one of six isolates from the South Asian, East Asian, South African, and South American clades, respectively. Widefield fluorescence microscopy showed cell number decreases at 1 mg/L AMB in cases of the South Asian, East Asian, and South African clades. These data draw attention to the weak killing activity of AMB against C. auris regardless of clades, even when MICs are low (≤1 mg/L). Thus, AMB efficacy is unpredictable in treatment of invasive C. auris infections.

In vitro and in vivo interaction of caspofungin with isavuconazole against Candida auris planktonic cells and biofilms

The in vitro and in vivo efficacy of caspofungin was determined in combination with isavuconazole against Candida auris. Drug-drug interactions were assessed utilising the fractional inhibitory concentration indices (FICIs), the Bliss independence model and an immunocompromised mouse model. Median planktonic minimum inhibitory concentrations (pMICs) of 23 C. auris isolates were between 0.5 and 2 mg/L and between 0.015 and 4 mg/L for caspofungin and isavuconazole, respectively. Median pMICs for caspofungin and isavuconazole in combination showed 2-128-fold and 2-256-fold decreases, respectively. Caspofungin and isavuconazole showed synergism in 14 out of 23 planktonic isolates (FICI range 0.03-0.5; Bliss cumulative synergy volume range 0-4.83). Median sessile MICs (sMIC) of 14 biofilm-forming isolates were between 32 and > 32 mg/L and between 0.5 and > 2 mg/L for caspofungin and isavuconazole, respectively. Median sMICs for caspofungin and isavuconazole in combination showed 0-128-fold and 0-512-fold decreases, respectively. Caspofungin and isavuconazole showed synergistic interaction in 12 out of 14 sessile isolates (FICI range 0.023-0.5; Bliss cumulative synergy volume range 0.13-234.32). In line with the in vitro findings, synergistic interactions were confirmed by in vivo experiments. The fungal kidney burden decreases were more than 3 log volumes in mice treated with combination of 1 mg/kg caspofungin and 20 mg/kg isavuconazole daily; this difference was statistically significant compared with control mice (p < 0.001). Despite the favourable effect of isavuconazole in combination with caspofungin, further studies are needed to confirm the therapeutic advantage of this combination when treating an infection caused by C. auris.

Comparison of In Vitro Killing Activity of Rezafungin, Anidulafungin, Caspofungin, and Micafungin against Four Candida auris Clades in RPMI-1640 in the Absence and Presence of Human Serum

Candida auris is an emerging and frequently multidrug-resistant pathogen against which the echinocandins are the preferred therapeutic option. We compared killing activities of anidulafungin, caspofungin, micafungin, and rezafungin against 13 isolates representing four C. auris clades (South Asian n = 3; East Asian n = 3; South African n = 3; South American n = 4, of which two were of environmental origin). Minimum inhibitory concentration MICs and killing kinetics in RPMI-1640 and RPMI-1640 plus 50% serum (50% serum) were determined. The four echinocandins were never fungicidal and induced large aggregates in RPMI-1640 and, less markedly, in 50% serum. Colony forming unit CFU decreases were found more consistently in 50% serum than in RPMI-1640. Isolates from the East Asian clade were killed at ≥1-≥ 4 mg/L with all echinocandins regardless of media. Anidulafungin and micafungin produced killing at peak drug serum concentration (8 mg/L) against environmental but not clinical isolates from the South American and the South African clades. Micafungin at ≥8 mg/L but not anidulafungin produced CFU decreases against the South Asian clade as well. In 50% serum, rezafungin at ≥1-≥ 8 mg/L produced killing against all four clades. The next generation echinocandin, rezafungin, showed the same or better activity at clinically attainable trough concentration regardless of media, compared with anidulafungin, caspofungin, and micafungin against all four tested C. auris clades.

New weapons to fight a new enemy: A systematic review of drug combinations against the drug-resistant fungus Candida auris

Candida auris is an emerging and drug-resistant pathogen. Drug combination is a promising approach against such pathogens. This study was conducted to provide an overview of all the studied drug combinations against C. auris. Relevant articles reporting results of any drug/non-drug combinations against C. auris were found by a systematic search in PubMed, Scopus and Web of Science (ISI), and in Google Scholar up to 1 October 2020. From 187 articles retrieved in the primary search, 23 met the inclusion criteria. In total, 124 different combinations including antifungal with antifungal (45), antifungal with other antimicrobials (11), antifungal with non-antimicrobials (32), antifungal with natural compounds (25) and between natural compounds (11) have been reported. Complete or partial synergistic effects have been reported for 3 out of 45 (6.67%) combinations of two antifungal agents, 8 out of 11 (72.73%) combinations involving antifungal agents and antimicrobials, 15 out of 32 (46.88%) of combinations between antifungal agents with non-antimicrobials, 16 out of 25 (64%) of combinations involving antifungal agents and natural compounds, and 3 out of 11 (22.27%) of combinations involving multiple natural compounds. Antagonistic interactions have been reported for 1 out of 32 (3.13%) and 8 out of 25 (32%) of combinations between antifungal drugs with non-antimicrobials and with natural compounds, respectively. Different drugs/compounds could potentiate the activity of antifungal drugs using this approach. However, despite the availability of this promising initial data, many more studies will be required to elucidate whether favourable interactions observed in vitro might translate into tangible clinical benefits.

Genomic epidemiology of a Cryptococcus neoformans case cluster in Glasgow, Scotland, 2018

In 2018, a cluster of two cases of cryptococcosis occurred at the Queen Elizabeth University Hospital (QEUH) in Glasgow, Scotland (UK). It was postulated that these cases may have been linked to pigeon droppings found on the hospital site, given there have been previous reports of Cryptococcus neoformans associated with pigeon guano. Although some samples of pigeon guano taken from the site yielded culturable yeast from genera related to Cryptococcus, they have since been classified as Naganishia or Papiliotrema spp., and no isolates of C. neoformans were recovered from either the guano or subsequent widespread air sampling. In an attempt to further elucidate any possible shared source of the clinical isolates, we used whole-genome sequencing and phylogenetic analysis to examine the relationship of the two Cryptococcus isolates from the QEUH cases, along with two isolates from sporadic cases treated at a different Glasgow hospital earlier in 2018. Our work demonstrated that these four clinical isolates were not clonally related; while all isolates were from the VNI global lineage and of the same mating type (MATα), the genotypes of the two QEUH isolates were separated by 1885 base changes and belonged to different sub-lineages, recently described as the intercontinental sub-clades VNIa-93 and VNIa-5. In contrast, one of the two sporadic 2018 clinical isolates was determined to belong to the VNIb sub-lineage and the other classified as a VNIV/VNI hybrid. Our work demonstrated that the two 2018 QEUH isolates and the two prior C. neoformans clinical isolates were all genetically distinct. It was not possible to determine whether the QEUH genotypes stemmed from independent sources or from the same source, i.e. pigeons carrying different genotypes, but it should be noted that whilst members of allied genera within the Tremellomycetes were isolated from the hospital environment, there were no environmental isolations of C. neoformans.

Comparison of in vivo pathogenicity of four Candida auris clades in a neutropenic bloodstream infection murine model

Candida auris is an emerging worldwide concern, but comparative data about the virulence of different C. auris lineages in mammalian hosts is lacking. Different isolates of the four prevalent C. auris clades (South Asian n = 5, East Asian n = 4, South African n = 5, and South American n = 5) were compared to assess their virulence in a neutropenic murine bloodstream infection model with C. albicans as reference. C. auris, regardless of clade, proved to be less virulent than C. albicans. Highest overall mortality at day 21 was observed for the South American clade (96%), followed by the South Asian (80%), South African (45%) and East Asian (44%) clades. Fungal burden results showed close correlation with lethality. Histopathological examination revealed large aggregates of blastoconidia and budding yeast cells in the hearts, kidneys and livers but not in the spleens. The myocardium of apparently healthy sacrificed mice as well as of mice found moribund showed contraction band necrosis in case of all lineages. Regardless of clade, the heart and kidneys were the most heavily affected organs. Isolates of the same clade showed differences in virulence in mice, but a markedly higher virulence of the South American clade was clearly demonstrated.

Bronchoalveolar lavage fluid IMMY Sona Aspergillus lateral-flow assay for the diagnosis of invasive pulmonary aspergillosis: a prospective, real life evaluation

Prompt and reliable diagnosis of invasive pulmonary aspergillosis (IPA) is essential for early initiation of antifungal therapy. We evaluated bronchoalveolar lavage (BAL) fluid IMMY Sona Aspergillus lateral-flow assay (IMMY LFA) in 92 individuals with suspected pulmonary infection. Sensitivity and specificity (vs. host factor but no IPA) of BAL IMMY LFA for diagnosis of IPA in individuals with any European Organisation for Research and Treatment of Cancer-defied "host factor" were 67% and 85%, respectively. Performance appeared better in individuals with renal transplantation (100%, 100%), compared to those with hematological malignancy and/or allogenic stem cell transplantation (70%, 78%). We found BAL IMMY LFA to be a convenient and useful addition to our diagnostic armory for IPA.

LAY ABSTRACT

We evaluated a new test for diagnosing invasive pulmonary aspergillosis from bronchoscopy samples. We tested 92 people and found that it was 67% sensitive and 85% specific (compared to diagnosis according to a set of internationally recognised criteria). We found this test convenient and useful.

The Neosartorya fischeri Antifungal Protein 2 (NFAP2): A New Potential Weapon against Multidrug-Resistant Candida auris Biofilms

Candida auris is a potential multidrug-resistant pathogen able to persist on indwelling devices as a biofilm, which serve as a source of catheter-associated infections. Neosartorya fischeri antifungal protein 2 (NFAP2) is a cysteine-rich, cationic protein with potent anti-Candida activity. We studied the in vitro activity of NFAP2 alone and in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin against C. auris biofilms. The nature of interactions was assessed utilizing the fractional inhibitory concentration index (FICI), a Bliss independence model, and LIVE/DEAD viability assay. NFAP2 exerted synergy with all tested antifungals with FICIs ranging between 0.312-0.5, 0.155-0.5, 0.037-0.375, 0.064-0.375, and 0.064-0.375 for fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. These results were confirmed using a Bliss model, where NFAP2 produced 17.54 μM²%, 2.16 μM²%, 33.31 μM²%, 10.72 μM²%, and 111.19 μM²% cumulative synergy log volume in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. In addition, biofilms exposed to echinocandins (32 mg/L) showed significant cell death in the presence of NFAP2 (128 mg/L). Our study shows that NFAP2 displays strong potential as a novel antifungal compound in alternative therapies to combat C. auris biofilms.

A pseudo-outbreak of Rhinocladiella similis in a bronchoscopy unit of a tertiary care teaching hospital in London, United Kingdom

Outbreaks of fungal infections due to emerging and rare species are increasingly reported in healthcare settings. We investigated a pseudo-outbreak of Rhinocladiella similis in a bronchoscopy unit of a tertiary care teaching hospital in London, UK. We aimed to determine route of healthcare-associated transmission and prevent additional infections. From July 2018 through February 2019, we detected a pseudo-outbreak of R. similis isolated from bronchoalveolar lavage (BAL) fluid samples collected from nine patients who had undergone bronchoscopy in a multispecialty teaching hospital, during a period of 8 months. Isolates were identified by MALDI-TOF mass spectrometry. Antifungal susceptibility testing was performed by EUCAST broth microdilution. To determine genetic relatedness among R. similis isolates, we undertook amplified fragment length polymorphism analysis. To determine the potential source of contamination, an epidemiological investigation was carried out. We reviewed patient records retrospectively and audited steps taken during bronchoscopy as well as the subsequent cleaning and decontamination procedures. Fungal cultures were performed on samples collected from bronchoscopes and automated endoscope washer-disinfector systems. No patient was found to have an infection due to R. similis either before or after bronchoscopy. One bronchoscope was identified to be used among all affected patients with positive fungal cultures. Physical damage was found in the index bronchoscope; however, no fungus was recovered after sampling of the affected scope or the rinse water of automated endoscope washer-disinfectors. Use of the scope was halted, and, during the following 12-month period, Rhinocladiella species were not isolated from any BAL specimen. All pseudo-outbreak isolates were identified as R. similis with high genetic relatedness (>90% similarity) on ALFP analysis. The study emphasises the emergence of a rare and uncommon black yeast R. similis, with reduced susceptibility to echinocandins, in a bronchoscope-related pseudo-outbreak with a potential water-related reservoir. Our findings highlight the importance of prolonged fungal culture and species-level identification of melanised yeasts isolated from bronchoscopy samples. Possibility of healthcare-associated transmission should be considered when R. similis is involved in clinical microbiology samples.

Farnesol increases the activity of echinocandins against Candida auris biofilms

Candida auris biofilms exhibit decreased susceptibility to echinocandins, which is associated with poorer clinical outcomes. Farnesol is a quorum-sensing molecule enhancing the activity of antifungals; therefore, we evaluated the in vitro effect of farnesol with anidulafungin, caspofungin, or micafungin against biofilms using fractional inhibitory concentration indexes (FICI), Bliss independence model, LIVE/DEAD-assay and scanning electron microscopy. Based on mathematical models, farnesol caused synergism in eleven out of twelve cases (FICIs range 0.133-0.507; Bliss synergy volume range 70.39-204.6 μM2%). This was confirmed by microscope images of combination-exposed biofilms. Our study showed the prominent effect of farnesol with echinocandins against C. auris biofilms.

In vitro activity of rezafungin against common and rare Candida species and Saccharomyces cerevisiae

BACKGROUND

Rezafungin is a novel echinocandin with excellent activity against common Candida species; however, limited data are available regarding rare Candida species.

METHODS

We determined the in vitro susceptibility of 689 clinical isolates of 5 common and 19 rare Candida species, as well as Saccharomyces cerevisiae. The activity of rezafungin was compared with that of anidulafungin, caspofungin, micafungin, amphotericin B and fluconazole, using CLSI broth microdilution methodology (Fourth Edition: M27).

RESULTS

Rezafungin MIC90 values were 0.06 mg/L for Candida albicans (n=125), Candida tropicalis (n=51), Candida dubliniensis (n=22), Candida inconspicua (n=41), Candida sojae (n=10), Candida lipolytica (n=10) and Candida pulcherrima (n=10), 0.12 mg/L for Candida glabrata (n=81), Candida krusei (n=53), Candida kefyr (n=52) and Candida fabianii (n=15), 0.25 mg/L for Candida lusitaniae (n=46) and Candida auris (n=19), 0.5 mg/L for Candida metapsilosis (n=15) and S. cerevisiae (n=21), 1 mg/L for Candida orthopsilosis (n=15) and Candida guilliermondii (n=27) and 2 mg/L for Candida parapsilosis sensu stricto (n=59). Caspofungin MIC90 values were 0.25-2 mg/L for all species, while micafungin and anidulafungin MIC90 values were similar to those of rezafungin. Fluconazole resistance was found in C. albicans (5.6%) and C. glabrata (4.9%); rezafungin was effective against these isolates as well. Amphotericin B MIC values did not exceed 2 mg/L.

CONCLUSIONS

Rezafungin showed excellent in vitro activity against both WT and azole-resistant Candida species, as well as against S. cerevisiae. Rezafungin had similar activity to other echinocandins (excluding caspofungin) against common Candida species and, notably, against clinically relevant uncommon Candida species.

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.

Exophiala campbellii causing a subcutaneous palmar cyst in an otherwise healthy UK resident

Exophiala is a ubiquitous genus encompassing more than forty species, a number of which have been associated with superficial or systemic infections in humans, and other hot- or cold-blooded animals. Here we report a human case of subcutaneous mycotic cyst caused by Exophiala campbellii. To our knowledge, this is only the third reported human infection caused by E. campbellii, all three of which involved subcutaneous nodules in patients who had resided in the United Kingdom.

Relative Frequency of Paradoxical Growth and Trailing Effect with Caspofungin, Micafungin, Anidulafungin, and the Novel Echinocandin Rezafungin against Candida Species

Rezafungin is a next-generation echinocandin that has favorable pharmacokinetic properties. We compared the occurrence of paradoxical growth (PG) and trailing effect (TE) characteristics to echinocadins with rezafungin, caspofungin, micafungin and anidulafungin using 365 clinical Candida isolates belonging to 13 species. MICs were determined by BMD method according to CLSI (M27 Ed4). Disconnected growth (PG plus TE) was most frequent with caspofungin (49.6%), followed by anidulafungin (33.7%), micafungin (25.7%), while it was least frequent with rezafungin (16.9%). PG was relatively common in the case of caspofungin (30.1%) but was rare in the case of rezafungin (3.0%). C. tropicalis, C. albicans, C. orthopsilosis and C. inconspicua exhibited PG most frequently with caspofungin, micafungin or anidulafungin. PG never occurred in the case of C. krusei isolates. Against C. tropicalis and C. albicans, echinocandins frequently showed PG after 24 h followed by TE after 48 h. All four echinocandins exhibited TE for the majority of C. auris and C. dubliniensis isolates. Disconnected growth was common among Candida species and was echinocandin- and species-dependent. In contrast to earlier echinocandins, PG was infrequently found with rezafungin.

Talaromycosis in a renal transplant recipient returning from South China

Talaromycosis is a fungal infection endemic in Southeast Asia. We report a case of a renal transplant recipient who developed infection after a trip to South China. She presented with constitutional symptoms and was found to have an FDG-avid lung mass. Histopathology demonstrated small yeast cells and culture grew Talaromyces marneffei. The patient was treated with 2 weeks of liposomal amphotericin B followed by itraconazole. The dose of tacrolimus was significantly reduced because of the interaction with itraconazole. Mycophenolate mofetil was discontinued. After 12 months of treatment, the mass had completely resolved. Talaromycosis has mainly been reported in patients with AIDS and is uncommon among solid organ transplant recipients. The immune response against T. marneffei infection is mediated predominantly by T cells and macrophages. The diagnosis may not be suspected outside of endemic areas. We propose a therapeutic approach in transplant patients by extrapolating the evidence from the HIV literature and following practices applied to other endemic mycoses.

In vitro and in vivo Effect of Exogenous Farnesol Exposure Against Candida auris

The spreading of multidrug-resistant Candida auris is considered as an emerging global health threat. The number of effective therapeutic regimens is strongly limited; therefore, development of novel strategies is needed. Farnesol is a quorum-sensing molecule with a potential antifungal and/or adjuvant effect; it may be a promising candidate in alternative treatment against Candida species including C. auris. To examine the effect of farnesol on C. auris, we performed experiments focusing on growth, biofilm production ability, production of enzymes related to oxidative stress, triazole susceptibility and virulence. Concentrations ranging from 100 to 300 μM farnesol caused a significant growth inhibition against C. auris planktonic cells for 24 h (p < 0.01-0.05). Farnesol treatment showed a concentration dependent inhibition in terms of biofilm forming ability of C. auris; however, it did not inhibit significantly the biofilm development at 24 h. Nevertheless, the metabolic activity of adhered farnesol pre-exposed cells (75 μM) was significantly diminished at 24 h depending on farnesol treatment during biofilm formation (p < 0.001-0.05). Moreover, 300 μM farnesol exerted a marked decrease in metabolic activity against one-day-old biofilms between 2 and 24 h (p < 0.001). Farnesol increased the production of reactive species remarkably, as revealed by 2',7'-dichlorofluorescein (DCF) assay {3.96 ± 0.89 [nmol DCF (OD₆₄₀)^-1] and 23.54 ± 4.51 [nmol DCF (OD₆₄₀)^-1] for untreated cells and farnesol exposed cells, respectively; p < 0.001}. This was in line with increased superoxide dismutase level {85.69 ± 5.42 [munit (mg protein)^-1] and 170.11 ± 17.37 [munit (mg protein)^-1] for untreated cells and farnesol exposed cells, respectively; p < 0.001}, but the catalase level remained statistically comparable between treated and untreated cells (p > 0.05). Concerning virulence-related enzymes, exposure to 75 μM farnesol did not influence phospholipase or aspartic proteinase activity (p > 0.05). The interaction between fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole and farnesol showed clear synergism (FICI ranges from 0.038 to 0.375) against one-day-old biofilms. Regarding in vivo experiments, daily 75 μM farnesol treatment decreased the fungal burden in an immunocompromised murine model of disseminated candidiasis, especially in case of inocula pre-exposed to farnesol (p < 0.01). In summary, farnesol shows a promising therapeutic or adjuvant potential in traditional or alternative therapies such as catheter lock therapy.

Lessons from isavuconazole therapeutic drug monitoring at a United Kingdom Reference Center

We determined isavuconazole serum concentrations for 150 UK patients receiving standard isavuconazole dosing regimens, including serial therapeutic drug monitoring for several patients on prolonged therapy. Mean trough isavuconazole concentrations in these patients were virtually identical to those reported previously from clinical trials, although greater variability was seen in patients below 18 years of age. Serial monitoring in patients receiving prolonged therapy suggested gradual, near-linear accumulation of the drug over many weeks.

MIC distributions for amphotericin B, fluconazole, itraconazole, voriconazole, flucytosine and anidulafungin and 35 uncommon pathogenic yeast species from the UK determined using the CLSI broth microdilution method

Background

Epidemiological cut-off values and clinical interpretive breakpoints have been developed for a number of antifungal agents with the most common Candida species that account for the majority of infections due to pathogenic yeasts species. However, less-common species, for which susceptibility data are limited, are increasingly reported in high-risk patients and breakthrough infections.

Methods

The UK National Mycology Reference Laboratory performs routine antifungal susceptibility testing of clinical yeast isolates submitted from across the UK. Between 2002 and 2016, &gt;32 000 isolates representing 94 different yeast species were referred to the laboratory. Here we present antifungal susceptibility profiles generated over this period for amphotericin B, fluconazole, voriconazole, itraconazole, anidulafungin and flucytosine against 35 species of uncommon yeast using CLSI methodologies. MIC data were interpreted against epidemiological cut-off values and clinical breakpoints developed with Candida albicans, in order to identify species with unusually skewed MIC distributions that potentially indicate resistance.

Results

Potential resistance to at least one antifungal agent (&gt;10% of isolates with MICs greater than the epidemiological cut-off or clinical breakpoint) was evidenced for 29/35 species examined here. Four species exhibited elevated MICs with all of the triazole antifungal drugs against which they were tested, and 21 species exhibited antifungal resistance to agents from at least two different classes of antifungal agent.

Conclusions

This study highlights a number of yeast species with unusual MIC distributions and provides data to aid clinicians in deciding which antifungal regimens may be appropriate when confronted with infections with rarer yeasts.

Rapid and robust identification of clinical isolates of Talaromyces marneffei based on MALDI-TOF mass spectrometry or dimorphism in Galleria mellonella

Talaromyces marneffei is a thermally dimorphic fungal pathogen that causes serious infections particularly in patients with human immunodeficiency virus (HIV). Although the mould form typically produces a characteristic red-diffusing pigment, and conidia from penicillate heads, several nonpathogenic Talaromyces/Penicillium species are morphologically and phenotypically similar. While those other species do not exhibit thermal dimorphism, conversion of T. marneffei to the distinctive fission yeast form in vitro is arduous and frequently incomplete. Here we show that T. marneffei can be rapidly and unambiguously discriminated from related nonpathogenic Talaromyces/Penicillium spp., either by matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry or conversion to fission yeast after introduction into Galleria mellonella. Conversion of T. marneffei conidia to the fission yeast form in G. mellonella larvae occurred as early as 24 h post inoculation at 37oC. Identification by MALDI-TOF was possible after supplementation of the commercial Bruker database with in-house mass spectral profiles created from either the yeast or mycelial phase of T. marneffei. In addition, we show that in-house generated mass spectral profiles could be successfully used to identify T. marneffei with a recently published on-line MALDI-TOF database, circumventing the need to create extensive in-house additional databases for rarely encountered fungal pathogens.

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.

A novel dermatophyte relative, Nannizzia perplicata sp. nov., isolated from a case of tinea corporis in the United Kingdom

A novel dermatophyte was isolated from skin scales of a female patient presenting with tinea corporis of the wrist and arm. Her principal risk factor was long-term corticosteroid use for underlying Lupus autoimmune syndrome. Microscopic examination of skin scales from lesions revealed hyphae consistent with dermatophyte infection, and a morphologically identical fungus grew in pure culture on all cultures of skin scales. Repeat isolation of the same organism from persistent lesions five months later confirmed the novel species as the causative agent. Microscopic examination revealed predominantly smooth, thin-walled macroconidia, with large numbers of unicellular aleuriospores of varied shapes and sizes. Since the isolate exhibited considerable microscopic pleomorphism, sharing morphological features consistent with several dermatophyte genera, it was subjected to multi-locus phylogenetic analyses employing a total of six different loci. Sequence analyses of all loci revealed that the isolate clustered with species within Nannizzia but diverged from all known members of the genus by 2 to 13% depending on locus analyzed. The isolate exhibited high minimum inhibitory concentrations for terbinafine in vitro, which might explain why the infection had failed to respond to two cycles of oral treatment with this antifungal agent. Interestingly, sequences in GenBank of an unnamed "Microsporum sp" isolated from leg skin of a patient in the Czech Republic showed greater than 99% identity across all of the loci analysed in common, indicating that this novel organism, which we describe here as Nannizzia perplicata sp. nov., is likely not restricted to the UK.

A black mould death: A case of fatal cerebral phaeohyphomycosis caused by Cladophialophora bantiana

Cladophialophora bantiana is a neurotropic mould and primary cause of cerebral phaeohyphomycoses, which presents with brain abscesses in both immunocompromised and immunocompetent individuals. It is associated with high mortality due to delay in diagnosis and absence of standardised therapy. We present a case of fatal cerebral phaeohyphomycosis in a 67-year-old Caucasian man. Diagnosis was achieved by histopathological examination of brain tissue followed by conventional culture and molecular identification. We highlight diagnostic and treatment challenges involved.