Containment strategies to address the expanding threat of multidrug-resistant Candida auris

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.

Risk factors and mortality of the newly emerging Candida auris in a university hospital in Saudi Arabia

Candida auris presents a global health threat. We investigated risk factors and mortality of Candida auris infections in a retrospective study in Saudi Arabia. We included 27 patients ≥14  with invasive Candida auris from 2015-2022, with median age 58, and 66.7% males. All patients had indwelling devices. The most common infection sources were central line-associated bloodstream infection in 17 (63.0%), and urinary tract infections in four (12%). Fever and shock were observed in nine patients (33.3%) each, and 22 (81%) were admitted to the intensive care unit. Common comorbidities were diabetes and heart disease in 13 (48.1%) patients each. The median hospital stay was 78 days, and the median Charlson index was 4. The C. auris cultures were 100% susceptible to voriconazole, caspofungin, and amphotericin, while three were fully susceptible to fluconazole (11.1%). Despite treatment, 18 (66.7%) patients died. In conclusion, invasive C. auris infection had varied presentations. All patients had indwelling devices, and many had lengthy hospital stays. All isolates were susceptible to amphotericin and echinocandins, while few were fully susceptible to fluconazole.

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.

Preclinical Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Antifungal Activity of Liposomal Amphotericin B

The improved safety profile and antifungal efficacy of liposomal amphotericin B (LAmB) compared to conventional amphotericin B deoxycholate (DAmB) is due to several factors including, its chemical composition, rigorous manufacturing standards, and ability to target and transit through the fungal cell wall. Numerous preclinical studies have shown that LAmB administered intravenously distributes to tissues frequently infected by fungi at levels above the minimum inhibitory concentration (MIC) for many fungi. These concentrations can be maintained from one day to a few weeks, depending upon the tissue. Tissue accumulation is dose-dependent with drug clearance occurring most rapidly from the brain and slowest from the liver and spleen. LAmB localizes in lung epithelial lining fluid, within liver and splenic macrophages and in kidney distal tubules. LAmB has been used successfully in therapeutic and prophylactic animal models to treat many different fungal pathogens, significantly increasing survival and reducing tissue fungal burden.

Global guidelines and initiatives from the European Confederation of Medical Mycology to improve patient care and research worldwide: New leadership is about working together

Invasive mycoses present a global challenge with expansion into new hosts, emergence of new pathogens, and development of multidrug resistance. In parallel, new antifungal agents and advanced laboratory diagnostic systems are being developed. In response to these evolving challenges, the European Confederation of Medical Mycology (ECMM) is committed to providing international expertise, guidance, and leadership with the key objectives of improving diagnosis, treatment, outcome, and survival of persons with invasive fungal diseases. Representing 25 affiliated National Medical Mycology Societies, the ECMM has developed several major ways to achieving these critical objectives: (a) tasking specific medical mycology working groups; (b) founding the ECMM Academy and Fellow program (FECMM); (c) expanding the goals of ECMM beyond the European region; (d) implementing the ECMM Excellence Centre Initiative in Europe; and (e) the ECMM Global Guidelines and Neglected Orphan Disease Guidance Initiatives focusing on mucormycosis, rare mould diseases, rare yeast diseases, and endemic mycoses. We believe that these important initiatives and other strategies of the ECMM will advance the field of medical mycology and improve the outcome of patients with invasive mycoses worldwide.

Invasive Fungal Infections in Patients with Hematological Malignancies: Emergence of Resistant Pathogens and New Antifungal Therapies

Invasive fungal infections caused by drug-resistant organisms are an emerging threat to heavily immunosuppressed patients with hematological malignancies. Modern early antifungal treatment strategies, such as prophylaxis and empirical and preemptive therapy, result in long-term exposure to antifungal agents, which is a major driving force for the development of resistance. The extended use of central venous catheters, the nonlinear pharmacokinetics of certain antifungal agents, neutropenia, other forms of intense immunosuppression, and drug toxicities are other contributing factors. The widespread use of agricultural and industrial fungicides with similar chemical structures and mechanisms of action has resulted in the development of environmental reservoirs for some drug-resistant fungi, especially azole-resistant Aspergillus species, which have been reported from four continents. The majority of resistant strains have the mutation TR34/L98H, a finding suggesting that the source of resistance is the environment. The global emergence of new fungal pathogens with inherent resistance, such as Candida auris, is a new public health threat. The most common mechanism of antifungal drug resistance is the induction of efflux pumps, which decrease intracellular drug concentrations. Overexpression, depletion, and alteration of the drug target are other mechanisms of resistance. Mutations in the ERG11 gene alter the protein structure of C-demethylase, reducing the efficacy of antifungal triazoles. Candida species become echinocandin-resistant by mutations in FKS genes. A shift in the epidemiology of Candida towards resistant non-albicans Candida spp. has emerged among patients with hematological malignancies. There is no definite association between antifungal resistance, as defined by elevated minimum inhibitory concentrations, and clinical outcomes in this population. Detection of genes or mutations conferring resistance with the use of molecular methods may offer better predictive values in certain cases. Treatment options for resistant fungal infections are limited and new drugs with novel mechanisms of actions are needed. Prevention of resistance through antifungal stewardship programs is of paramount importance.