In vitro interactions of proton pump inhibitors and azoles against pathogenic fungi

Introduction

Azole resistance has been increasingly reported and become an issue for clinical managements of invasive mycoses. New strategy with combination therapy arises as a valuable and promising alternative option. The aim of the present study is to investigate the in vitro combinational effect of proton pump inhibitors (PPIs) and azoles against pathogenic fungi.

Methods

In vitro interactions of PPIs including omeprazole (OME), lansoprazole (LAN), pantoprazole (PAN), and rabeprazole (RAB), and commonly used azoles including itraconazole (ITC), posaconazole (POS), voriconazole (VRC) and fluconazole (FLC), were investigated via broth microdilution chequerboard procedure adapted from the CLSI M27-A3 and M38-A2. A total of 67 clinically isolated strains, namely 27 strains of Aspergillus spp., 16 strains of Candida spp., and 24 strains of dematiaceous fungi, were studied. C. parapsilosis (ATCC 22019) and A. flavus (ATCC 204304) was included to ensure quality control.

Results

PPIs individually did not exert any significant antifungal activity. The combination of OME with ITC, POS, or VRC showed synergism against 77.6%, 86.6%, and 4% strains of tested pathogenic fungi, respectively, while synergism of OME/FLC was observed in 50% strains of Candida spp. Synergism between PAN and ITC, POS, or VRC was observed against 47.8%, 77.6% and 1.5% strains of tested fungi, respectively, while synergism of PNA/FLC was observed in 50% strains of Candida spp. Synergism of LAN with ITC, POS, or VRC was observed against 86.6%, 86.6%, and 3% of tested strains, respectively, while synergism of LAN/FLC was observed in 31.3% strains of Candida spp. Synergy of the combination of RAB with ITC, POS, or VRC was observed against 25.4%, 64.2%, and 4.5% of tested strains, respectively, while synergism of RAB/FLC was observed in 12.5% of Candida spp.. Among PPIs, synergism was least observed between RAB and triazoles, while among triazoles, synergism was least observed between VRC and PPIs. Among species, synergy was much more frequently observed in Aspergillus spp. and dematiaceous fungi as compared to Candida spp. Antagonism between PPIs with ITC or VRC was occasionally observed in Aspergillus spp. and dematiaceous fungi. It is notable that PPIs combined with azoles showed synergy against azole resistant A. fumigatus, and resulted in category change of susceptibility of ITC and POS against Candida spp.

Discussion

The results suggested that PPIs combined with azoles has the potential to enhance the susceptibilities of azoles against multiple pathogenic fungi and could be a promising strategy to overcome azole resistance issues. However, further investigations are warranted to study the combinational efficacy in more isolates and more species, to investigate the underlying mechanism of interaction and to evaluate the potential for concomitant use of these agents in human.

Exophiala dermatitidis fungal infective endocarditis on prosthetic mitral valve

Fungal infective endocarditis, although rare, carries a high mortality risk. We present a case of successful multidisciplinary management of Exophiala dermatitidis infective endocarditis in an immunocompetent male with a bio-prosthetic mitral valve. This case highlights the clinical presentation and provides valuable treatment insights into this rare fungal entity. Prompt consideration of fungal pathogens in predisposed patients, expedited detection through non-culture-based tests, and a combined surgical and prolonged antifungal approach are pivotal.

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

In Vitro and In Vivo Evaluation of Synergistic Effects of Everolimus in Combination with Antifungal Agents on Exophiala dermatitidis

To investigate the combined function of the novel oral mTOR inhibitor, everolimus, with antifungal agents and their potential mechanisms against Exophiala dermatitidis, the CLSI microliquid-based dilution method M38-A2, chequerboard technique, and disk diffusion testing were performed. The efficacy of everolimus was evaluated in combination with itraconazole, voriconazole, posaconazole, and amphotericin B against 16 clinically isolated strains of E. dermatitidis. The synergistic effect was determined by measuring the MIC and fractional inhibitory concentration index. Dihydrorhodamine 123 was used for the quantification of ROS levels. The differences in the expression of antifungal susceptibility-associated genes were analyzed following different types of treatment. Galleria mellonella was used as the in vivo model. While everolimus alone showed minimal antifungal effects, combinations with itraconazole, voriconazole, posaconazole, or amphotericin B resulted in synergy in 13/16 (81.25%), 2/16 (12.5%), 14/16 (87.75%), and 5/16 (31.25%) of isolates, respectively. The disk diffusion assay revealed that the combination of everolimus and antifungal drugs showed no significant increase in the inhibition zones compared with the single agent, but no antagonistic effects were observed. Combination of everolimus and antifungal agents resulted in increased ROS activity (everolimus + posaconazole versus posaconazole [P < 0.05], everolimus + amphotericin B versus amphotericin B [P < 0.002]). Simultaneously, compared to mono-treatment, the combination of everolimus + itraconazole suppressed the expression of MDR2 (P < 0.05) and the combination of everolimus + amphotericin B suppressed the expression of MDR3 (P < 0.05) and CDR1B (P < 0.02). In vivo, combinations of everolimus and antifungal agents improved survival rates, particularly the combination of everolimus + amphotericin B (P < 0.05). In summary, the in vivo and in vitro experiments performed in our study suggest that the combination of everolimus with azoles or amphotericin B can have synergistic effects against E. dermatitidis, potentially due to the induction of ROS activity and inhibition of efflux pumps, providing a promising new approach for the treatment of E. dermatitidis infections. IMPORTANCE Cancer patients with E. dermatitidis infection have high mortality if untreated. Clinically, the conventional treatment of E. dermatitidis is poor due to the long-term use of antifungal drugs. In this study, we have for the first time investigated the interaction and action mechanism of everolimus combined with itraconazole, voriconazole, posaconazole, and amphotericin B on E. dermatitidis in vitro and in vivo, which provided new ideas and direction for further exploring the mechanism of drug combination and clinical treatment of E. dermatitidis.

A Repertoire of Clinical Non-Dermatophytes Moulds

Humans are constantly exposed to micromycetes, especially filamentous fungi that are ubiquitous in the environment. In the presence of risk factors, mostly related to an alteration of immunity, the non-dermatophyte fungi can then become opportunistic pathogens, causing superficial, deep or disseminated infections. With new molecular tools applied to medical mycology and revisions in taxonomy, the number of fungi described in humans is rising. Some rare species are emerging, and others more frequent are increasing. The aim of this review is to (i) inventory the filamentous fungi found in humans and (ii) provide details on the anatomical sites where they have been identified and the semiology of infections. Among the 239,890 fungi taxa and corresponding synonyms, if any, retrieved from the Mycobank and NCBI Taxonomy databases, we were able to identify 565 moulds in humans. These filamentous fungi were identified in one or more anatomical sites. From a clinical point of view, this review allows us to realize that some uncommon fungi isolated in non-sterile sites may be involved in invasive infections. It may present a first step in the understanding of the pathogenicity of filamentous fungi and the interpretation of the results obtained with the new molecular diagnostic tools.

Multidisciplinary management of disseminated Exophiala dermatitidis mycosis in an infant with mixed phenotype acute leukemia: a case report

Background

Exophiala dermatitidis is a dematiaceous fungus isolated from various environmental sources. Systemic E. dermatitidis infections can lead to fatal outcomes, and treatment has not yet been standardized. Although E. dermatitidis is also known to cause cutaneous infection, it has not been previously reported to appear as ecthyma gangrenosum (EG), an uncommon cutaneous lesion in neutropenic patients that is mainly caused by Pseudomonas aeruginosa.

Case presentation

A 2-month-old male infant with mixed-phenotype acute leukemia presented with prolonged fever unresponsive to antibacterial and antifungal agents during myelosuppression due to remission induction therapy. He also presented with skin lesions on the left wrist and left lower quadrant of the abdomen. The abdominal lesion gradually turned black and necrotic, which was consistent with the findings of the EG. E. dermatitidis was isolated from the blood, stool, wrist skin, and endotracheal aspirate. During hematopoietic recovery, consolidation in both lungs was evident. Multiagent antifungal treatment failed to eliminate E. dermatitidis from blood. In order to salvage the central venous catheter, ethanol lock therapy (ELT) was adopted, following which the blood culture became negative. The abdominal lesion that evolved as a necrotic mass connecting the small intestine and subcutaneous tissue adjacent to the skin was surgically resected. After these interventions, the general condition improved.

Conclusion

Disseminated E. dermatitidis mycosis in the neutropenic infant was successfully managed with a multidisciplinary treatment consisting of multiagent antifungal treatment, ELT, and surgery.

Dematiaceous fungal infections in solid organ transplantation: systematic review and bayesian meta-analysis

BACKGROUND

Dematiaceous fungi cause a number of infectious syndromes referred to as phaeohyphomycosis among both immunocompetent and immunocompromised hosts. We performed a systematic review to characterize these infections in solid organ transplant recipients (SOTR).

METHODS

We searched PubMed database (last searched 1/6/2022) for English-language reports on dematiaceous fungal infections in SOTR. Included reports needed individualized demographic, treatment, and outcome data; pediatric reports were excluded. A universally applicable bias assessment was performed on reports. Models for infection type and outcome were created using the Bayesian paradigm.

RESULTS

We included 149 reports on 201 cases of dematiaceous fungal infections in SOTR. The mean age was 54 years, 72% were men, and kidney recipients accounted for 61% of cases. Skin and soft tissue infection (SSTI) was the most common infectious syndrome (73%). Death from infection occurred in 7% of cases (14/201), with disseminated (32%) cases having the highest mortality. Our model for infection type predicted the relative probability of central nervous system infection to be highest in liver recipients. Across all transplant types, higher relative probabilities of disseminated and pulmonary infections occur in the early post-transplant period, and the predicted probabilities for these infection types decreased after 100 months post-transplantation.

DISCUSSION

We identified SSTI as the most common dematiaceous fungal infections in SOTR. Disseminated infections carried the worst prognosis. The evidence in this review is limited by the heterogeneity of included cases. No funding source was used, and this review's protocol was not registered. This article is protected by copyright. All rights reserved.

In Vitro and In Vivo Interactions of TOR Inhibitor AZD8055 and Azoles against Pathogenic Fungi

In the present study, in vitro and in vivo interactions of TOR inhibitor AZD8055 and azoles, including itraconazole, voriconazole, posaconazole and fluconazole, against a variety of pathogenic fungi were investigated. A total of 69 isolates were studied via broth microdilution checkerboard technique, including 23 isolates of Aspergillus spp., 20 isolates of Candida spp., 9 isolates of Cryptococcus neoformans complex, and 17 isolates of Exophiala dermatitidis. The results revealed that AZD8055 individually did not exert any significant antifungal activity. However, synergistic effects between AZD8055 and itraconazole, voriconazole or posaconazole were observed in 23 (33%), 13 (19%) and 57 (83%) isolates, respectively, including azole-resistant A. fumigatus strains and Candida spp., potentiating the efficacy of azoles. The combination effect of AZD8055 and fluconazole was investigated against non-auris Candida spp. and C. neoformans complex. Synergism between AZD8055 and fluconazole was observed in six strains (60%) of Candida spp., resulting in reversion of fluconazole resistance. Synergistic combinations resulted in 4-fold to 256-fold reduction of effective MICs of AZD8055 and azoles. No antagonism was observed. In vivo effects of AZD8055-azole combinations were evaluated by survival assay in Galleria mellonella model infected with A. fumigatus strain AF002, E. dermatitidis strain BMU00038, C. auris strain 383, C. albicans strain R15, and C. neoformans complex strain Z2. AZD8055 acted synergistically with azoles and significantly increased larvae survival (P < 0.05). In summary, the results suggested that AZD8055 combined with azoles may help to enhance the antifungal susceptibilities of azoles against pathogenic fungi and had the potential to overcome azole resistance issues.

IMPORTANCE Limited options of antifungals and the emergence of drug resistance in fungal pathogens has been a multifaceted clinical challenge. Combination therapy represents a valuable alternative to antifungal monotherapy. The target of rapamycin (TOR), a conserved serine/threonine kinase from yeast to humans, participates in a signaling pathway that governs cell growth and proliferation in response to nutrient availability, growth factors, and environmental stimuli. AZD8055 is an orally bioavailable, potent, and selective TOR kinase inhibitor that binds to the ATP binding cleft of TOR kinase and inhibits both TORC1 and TORC2. Synergism between AZD8055 and azoles suggested that the concomitant application of AZD8055 and azoles may help to enhance azole therapeutic efficacy and impede azole resistance. TOR inhibitor with fungal specific target is promising to be served as combination regimen with azoles.

In vitro activities of 8 antifungal drugs against 126 clinical and environmental Exophiala isolates

BACKGROUND

Exophiala is the main genus of black fungi comprising numerous opportunistic species. Data on antifungal susceptibility of Exophiala isolates are limited, while infections are potentially fatal.

MATERIALS AND METHODS

In vitro activities of eight antifungal drugs (AMB, five azoles, two echinocandins) against 126 clinical (n = 76) and environmental (n = 47) isolates from around the world were investigated. E. oligosperma (n = 58), E. spinifera (n = 33), E. jeanselmei (n = 14) and E. xenobiotica (n = 21) were included in our dataset.

RESULTS

The resulting MIC₉₀ s of all strains were as follows, in increasing order: posaconazole 0.063 μg/ml, itraconazole 0.125 μg/ml, voriconazole and amphotericin B 1 μg/ml, isavuconazole 2 μg/ml, micafungin and caspofungin 4 μg/ml, and fluconazole 64 μg/ml. Posaconazole, itraconazole and micafungin were the drugs with the best overall activity against Exophiala species. Fluconazole could not be considered as a treatment choice. No significant difference could be found among antifungal drug activities between these four species, neither in clinical nor in environmental isolates.

CONCLUSION

Antifungal susceptibility data for Exophiala spp. are crucial to improve the management of this occasionally fatal infection and the outcome of its treatment.

A fatal case of Exophiala dermatitidis meningoencephalitis in an immunocompetent host: A case report and literature review

BACKGROUND

Central nervous system (CNS) infection due to Exophiala dermatitidis is rare and fatal, and primarily reported in immunocompromised patients or those with caspase recruitment domain-containing protein 9 deficiency. Herein, we describe a case of an otherwise healthy person (without underlying disease or gene deficiency) diagnosed with Exophiala dermatitidis meningoencephalitis. The patient achieved clinical remission under high-dose antifungal therapy in the first 14 months but died after 2 years of the therapy.

CASE PRESENTATION

A 15-year-old student with headache and fever was admitted to our department. Lumbar puncture showed increased cerebrospinal fluid (CSF) pressure, moderately high CSF protein levels and cell counts, and a remarkable decrease in CSF glucose and chloride. Magnetic resonance imaging of the brain revealed multiple lesions and cerebral pia mater enhancement. CSF culture confirmed E. dermatitidis infection. We administered 4-week antifungal therapy of amphotericin B, but his CSF culture remained positive. After receiving the 12-week standard dose of voriconazole (200 mg q12h), the patient's CSF culture became negative, but his condition deteriorated with intracranial lesion enlargement. We administered a high-dose voriconazole therapy (600-800 mg per day) for 12 months, which led to clinical remission. The voriconazole dose was reduced due to adverse effects including hepatic dysfunction and hypokalemia, and the disease progressed with high intracranial pressure and epileptic seizures.

CONCLUSIONS

CNS infection caused by E. dermatitidis is fatal and the most serious form of fungal infection. Initially, high-dose and long-term antifungal therapy could be effective. Gene defect and related antifungal immunodeficiency may be the most important pathogenic and lethal factor.

Endocarditis in kidney transplant recipients: a systematic review

Infective Endocarditis (IE) carries significant mortality. Bacteremia, which is a predisposing factor for IE, occurs more frequently in immunocompromised individuals. Interestingly, IE in kidney transplant recipients has not been adequately described. The aim of this study was to systematically review all published cases of IE in kidney transplant recipients and describe their epidemiology, microbiology, clinical characteristics, treatment and outcomes. A systematic review of PubMed (through 13^th December 2019) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of IE in kidney transplant recipients was performed. A total of 60 studies, containing data of 117 patients, were included in the analysis. The most common causative pathogens were gram-positive microorganisms in 57.4%, gram-negative microorganisms in 14.8%, fungi in 20%, while in 18.9% of cases, IE was culture-negative. Aortic valve was the most commonly infected valve followed by mitral, tricuspid and the pulmonary valve. Diagnosis was set with a transthoracic ultrasound in half the cases, followed by transesophageal ultrasound and autopsy. Fever was present in most cases, while embolic phenomena were noted in two out of five cases. Aminoglycosides, cephalosporins and aminopenicillins were the most commonly used antimicrobials, and surgical management was performed in one out of three cases. Clinical cure was noted in 60.9%, while overall mortality was 45.3%. To conclude, this systematic review thoroughly describes IE in kidney transplant recipients and provides information on epidemiology, clinical presentation, treatment and outcomes. Moreover, it identifies the emerging role of Enterococci, gram-negatives and fungi in IE in this population.

Exophiala dermatitidis as a cause of central line associated bloodstream infection in an infant: Case report and literature review

BACKGROUND

Exophiala dermatitidis is a dematiaceous fungus known to cause superficial, subcutaneous, cutaneous and deep seated infections, and rarely central line associated bloodstream infection (CLABSI). A case of CLABSI due to E. dermatitidis in an infant is described.

CASE REPORT

Clinical and laboratory data were extracted from patient's chart and laboratory records. The isolate was identified as E. dermatitidis by phenotypic characterization and sequencing of the ITS and LSU regions of the ribosomal DNA. Medline search was done to review all cases of CLABSI due to E. dermatitidis. Among the azoles tested, posaconazole (0.06mg/l), voriconazole (0.03mg/l) and itraconazole (0.03mg/l) showed very low MICs when compared to fluconazole (4mg/l) CONCLUSIONS: As we did not found in the literature any case of CLABSI due to E. dermatitidis in an infant, we report the first one. Sequencing is a mandatory method for accurately identifying this species. Prompt removal of the central line, followed by a treatment with amphotericin B or an azole, seems to be the most effective treatment.

In vitro and in vivo Study of Antifungal Effect of Pyrvinium Pamoate Alone and in Combination With Azoles Against Exophiala dermatitidis

Infections of Exophiala dermatitidis are often chronic and recalcitrant. Combination therapies with novel compounds and azoles could be an effective solution. Previously, we have demonstrated that pyrvinium pamoate exerted antifungal activity alone and favorable synergy with azoles against planktonic E. dermatitidis. Herein, the underlying antifungal mode of action were investigated. Pyrvinium alone showed sessile MIC50 (SMIC50) of 8->16 μg/ml against E. dermatitidis biofilms. However, synergism of PP with itraconazole, voriconazole, and posaconazole were observed against 16 (88.9%), 9 (50%), and 13 (72.2%) strains of E. dermatitidis biofilms. In accordance with in vitro susceptibilities, pyrvinium alone at concentration of 2 μg/ml resulted in significant growth restriction of planktonic E. dermatitidis. Pyrvinium alone resulted in reduction of biofilm formation. Higher concentration of pyrvinium was associate with more progressive reduction of biofilm mass. The in vivo activity of pyrvinium alone and combined with azoles was evaluated using Galleria mellonella model. Pyrvinium alone significantly improved the survival rate of larvae (P < 0.0001). The combination of pyrvinium and voriconazole or posaconazole acted synergistically in vivo (P < 0.05). Fungal burden determination revealed significant reduction of numbers of colony forming unit (CFU) in larvae treated with pyrvinium-itraconazole and pyrvinium-posaconazole compared to itraconazole or posaconazole alone group, respectively. The effect of pyrvinium on apoptosis, expression of TOR and HSP90, and drug efflux reversal were evaluated by PI/Annexin V staining, Real-Time Quantitative PCR and Rhodamine 6G assay, respectively. Pyrvinium alone or combined with azoles significantly (P < 0.05) increased late apoptosis or necrosis of E. dermatitidis cells. Pyrvinium combined with posaconazole significantly decreased the expression of TOR and Hsp90 compared to posaconazole alone group (P < 0.05). Pyrvinium resulted in significant (P < 0.05) decrease of the efflux of Rhodamine 6G. These findings suggested pyrvinium could be a promising synergist with azoles. The underlying mechanisms could be explained by inducing apoptosis/necrosis, inhibition of drug efflux pumps, and signaling pathways related with stress response and growth control.

Fungal endocarditis in transplant recipients: A systematic review

BACKGROUND

Invasive fungal infections remain a major cause of morbidity and mortality in transplant recipients. Moreover, Fungal Infective Endocarditis (FIE) is a rare infection that carries a higher mortality than bacterial IE in normal host, while in transplant recipients may be even higher. The purpose of this study was to systemically review all published cases of FIE in solid organ and allogeneic bone marrow transplant recipients, describe the epidemiology, microbiology, clinical characteristics, treatment and outcomes of these infections, and to identify risk factors for mortality by FIE.

METHODS

A systematic review of PubMed, Scopus and Cochrane Library (through 20 May 2020) for studies providing epidemiological, clinical, microbiological and treatment data and outcomes of FIE in transplant recipients was performed.

RESULTS

A total of 60 studies, containing data of 72 patients, were included. The most common transplants were those of the kidney and the liver, while the commonest causative pathogen was Aspergillus. Mitral valve was the commonest infected intracardiac site, followed by mural endocardium. Diagnosis was made with transthoracic echocardiography in 44.3%, while the diagnosis was made at autopsy in 37.3%. Embolic phenomena were the commonest clinical presentation, followed by fever, heart failure and endophthalmitis. Amphotericin B, voriconazole and caspofungin were the commonest antifungals used for treatment of FIE. Clinical cure was noted in 26.9%, while overall mortality was 78.6%. Amphotericin B or caspofungin use was negatively associated with overall mortality.

CONCLUSIONS

This systematic review thoroughly describes IE in transplant recipients and provides information on epidemiology, clinical presentation, treatment and outcomes.

In Vitro and In Vivo Study on the Synergistic Effect of Minocycline and Azoles against Pathogenic Fungi

In vitro and in vivo interactions of minocycline and azoles, including itraconazole, voriconazole, and posaconazole, against filamentous pathogenic fungi were investigated. A total of 56 clinical isolates were studied in vitro via broth microdilution checkerboard technique, including 20 strains of Aspergillus fumigatus, 7 strains of Aspergillus flavus, 16 strains of Exophiala dermatitidis, 10 strains of Fusarium solani, and 3 strain s of Fusarium oxysporum The results revealed that minocycline did not exhibit any significant antifungal activity against any of the tested strains. However, favorable synergy of minocycline with itraconazole, voriconazole, or posaconazole was observed against 34 (61%), 28 (50%), and 38 (68%) isolates, respectively, including azole-resistant A. fumigatus and Fusarium spp. with inherently high MICs of azoles. Synergistic combinations resulted in 4-fold to 16-fold reduction of effective MICs of minocycline and azoles. No antagonism was observed. In vivo effects of minocycline-azole combinations were evaluated by survival assay in a Galleria mellonella model infected with E. dermatitidis strain BMU00034; F. solani strain FS9; and A. fumigatus strains AF293, AFR1, and AFR2. Minocycline acted synergistically with azoles and significantly increased larvae survival in all isolates (P < 0.001), including azole-resistant A. fumigatus and azole-inactive Fusarium spp. In conclusion, the results suggested that minocycline combined with azoles may help to enhance the antifungal susceptibilities of azoles against pathogenic fungi and had the potential to overcome azole resistance issues.

Exophiala dermatitidis: Key issues of an opportunistic fungal pathogen

The black yeast Exophiala dermatitidis is an opportunistic pathogen, causing phaeohyphomycosis in immunosuppressed patients, chromoblastomycosis and fatal infections of the central nervous system in otherwise healthy Asian patients. In addition, it is also regularly isolated from respiratory samples from cystic fibrosis patients, with rates varying between 1% and 19%.Melanin, as part of the cell wall of black yeasts, is one major factor known contributing to the pathogenicity of E. dermatitidis and increased resistance against host defense and anti-infective therapeutics. Further virulence factors, e.g. the capability to adhere to surfaces and to form biofilm were reported. A better understanding of the pathogenicity of E. dermatitidis is essential for the development of novel preventive and therapeutic strategies. In this review, the current knowledge of E. dermatitidis prevalence, clinical importance, diagnosis, microbiological characteristics, virulence attributes, susceptibility, and resistances as well as therapeutically strategies are discussed.

A fatal case of Exophiala dermatitidis disseminated infection in an allogenic hematopoietic stem cell transplant recipient during micafungin therapy

Exophiala dermatitidis is a dematiaceous fungus that is increasingly becoming the cause of fungal infection in immunocompromised patients. However, the risk factors and optimal treatment modality for E. dermatitidis infection are unknown to date. Herein, we present a fatal case of E. dermatitidis infection in an adult patient that developed after allogeneic hematopoietic stem cell transplantation for chronic active Epstein-Barr virus infection. The dematiaceous fungus caused a breakthrough fungemia despite prophylactic administration of micafungin. Although the patient was intensively treated with liposomal-amphotericin B and voriconazole, serum level of beta-D-glucan continuously increased, and the patient eventually died because of cerebral hemorrhage. An autopsy found multiple involvements of the fungal infection at the bilateral lungs, thoracic cavities, diaphragm, and thyroid. To the best of our knowledge, this is the first reported case of E. dermatitidis infection involving these tissues as determined via autopsy. This case highlights the importance of attention for Exophiala infection in immunocompromised individuals in those given antifungal therapy with echinocandins.

In vitro interactions between 17-AAG and azoles against Exophiala dermatitidis

BACKGROUND

Exophiala dermatitidis causes a variety of illnesses in humans which are always refractory to available treatment modalities. Hsp90 governs crucial stress responses, cell wall repair mechanisms and antifungal resistance in pathogenic fungi. Thus, targeting Hsp90 with specific inhibitors holds considerable promise as combination strategy.

OBJECTIVES

To investigate the antifungal effect of 17-AAG alone or combined with azoles against E. dermatitidis.

METHODS

In vitro interactions of 17-AAG, a Hsp90 inhibitor, and azoles including itraconazole, voriconazole and posaconazole against E. dermatitidis were evaluated via broth microdilution chequerboard technique, adapted from the CLSI M38-A2 method. A total of 18 clinical strains were studied. Candida parapsilosis (ATCC22019) was included to ensure quality control.

RESULTS AND CONCLUSIONS

17-AAG alone exhibited minimal antifungal activity against all tested isolates. However, synergistic effects between 17-AAG and posaconazole, itraconazole or voriconazole were observed against 15 (83.3%), 12 (66.7%) and 1 (5.6%) isolates of E. dermatitidis, respectively. The effective working ranges of 17-AAG in synergistic combinations were mostly within 2-8 μg/mL. No antagonism was observed. In conclusion, harnessing fungal Hsp90 with 17-AAG might prove a potential antifungal regimen for E. dermatitidis infections. However, due to the host toxicity of 17-AAG, more efforts are needed to develop fungal specific Hsp90 inhibitors.

Disseminated Exophiala dermatitidis causing septic arthritis and osteomyelitis

Background

Exophiala dermatitidis is a melanized fungus isolated from many environmental sources. Infections caused by Exophiala species are typically seen in immunocompromised hosts and manifest most commonly as cutaneous or subcutaneous disease. Systemic infections are exceedingly rare and associated with significant morbidity and mortality

Case presentation

A 28-year-old female originally from India presented with fevers, chills, weight loss and increasing back pain. She had a recent diffuse maculopapular rash that resulted in skin biopsy and a tentative diagnosis of sarcoidosis, leading to administration of azathioprine and prednisone. An MRI of her spine revealed a large paraspinal abscess requiring surgical intervention and hardware placement. Cultures from the paraspinal abscess grew a colony of dark pigmented mold. Microscopy of the culture revealed a melanized fungus, identified as Exophiala dermatitidis. Voriconazole was initially utilized, but due to relapse of infection involving the right iliac crest and left proximal humerus, she received a prolonged course of amphotericin B and posaconazole in combination and required 7 separate surgical interventions. Prolonged disease stability following discontinuation of therapy was achieved.

Conclusions

Described is the first identified case of disseminated Exophiala dermatitidis causing osteomyelitis and septic arthritis in a patient on immunosuppressive therapy. A positive outcome was achieved through aggressive surgical intervention and prolonged treatment with broad-spectrum antifungal agents.

Comparative Ecology of Capsular Exophiala Species Causing Disseminated Infection in Humans

Exophiala spinifera and Exophiala dermatitidis (Fungi: Chaetothyriales) are black yeast agents potentially causing disseminated infection in apparently healthy humans. They are the only Exophiala species producing extracellular polysaccharides around yeast cells. In order to gain understanding of eventual differences in intrinsic virulence of the species, their clinical profiles were compared and found to be different, suggesting pathogenic strategies rather than coincidental opportunism. Ecologically relevant factors were compared in a model set of strains of both species, and significant differences were found in clinical and environmental preferences, but virulence, tested in Galleria mellonella larvae, yielded nearly identical results. Virulence factors, i.e., melanin, capsule and muriform cells responded in opposite direction under hydrogen peroxide and temperature stress and thus were inconsistent with their hypothesized role in survival of phagocytosis. On the basis of physiological profiles, possible natural habitats of both species were extrapolated, which proved to be environmental rather than animal-associated. Using comparative genomic analyses we found differences in gene content related to lipid metabolism, cell wall modification and polysaccharide capsule production. Despite the fact that both species cause disseminated infections in apparently healthy humans, it is concluded that they are opportunists rather than pathogens.

Synergistic Effects of Tacrolimus and Azoles against Exophiala dermatitidis

In vitro interactions of tacrolimus, a calcineurin inhibitor, and azoles, including itraconazole, voriconazole, and posaconazole, against planktonic cells and biofilms of Exophiala dermatitidis were assessed via a broth microdilution checkerboard technique. A total of 16 clinical isolates were studied. The results revealed favorable synergistic inhibitory activity between tacrolimus and itraconazole, voriconazole, or posaconazole against 68.8%, 87.5%, and 100% of tested strains of planktonic E. dermatitidis, respectively.However, limited synergism was observed against biofilms of E. dermatitidis No antagonism was observed in all combinations.

A case of Exophiala dermatitidis infection in a child after allogeneic stem cell transplantation: case report and literature review of paediatric cases

Introduction.Exophiala dermatitidisis a relatively common environmental black yeast with worldwide distribution and is a rare cause of fungal infection, mostly in patients with certain predisposing factors. Due to the rarity of the infection, little is known about the specific predisposing factors, way of infection or treatment.

Case presentation. Here, we report what is to our knowledge the first case of E. dermatitidis infection in a child after allogeneic stem cell transplantation. We also review all paediatric cases reported in the literature since 1993.

Conclusion. This is, to our knowledge, the first reported case of E. dermatitidis infection in a child after allogeneic stem cell transplantation. This report should increase the awareness of E. dermatitidis in immunocompromised paediatric patients, particularly after stem cell transplantation.

Exophiala (Wangiella) dermatitidis Prosthetic Aortic Valve Endocarditis and Prosthetic Graft Infection in an Immune Competent Patient

Exophiala (Wangiella) dermatitidis is an emerging dematiaceous fungus associated with high mortality rates and is a rare cause of endocarditis. We describe the first case of E. dermatitidis endocarditis of a prosthetic aortic valve and aortic graft in an immune competent patient with no clear risk factors of hematological acquisition.

INK128 Exhibits Synergy with Azoles against Exophiala spp. and Fusarium spp

Infections of Exophiala spp. and Fusarium spp. are often chronic and recalcitrant. Systemic disseminations, which mostly occur in immunocompromised patients, are often refractory to available antifungal therapies. The conserved target of rapamycin (TOR) orchestrates cell growth and proliferation in response to nutrients and growth factors, which are important for pathogenicity and virulence. INK128 is a second-generation ATP-competitive TOR inhibitor, which binds the TOR catalytic domain and selectively inhibits TOR. In the present study, we investigated the in vitro activities of INK128 alone and the interactions of INK128 with conventional antifungal drugs including itraconazole, voriconazole, posaconazole, and amphotericin B against 18 strains of Exophiala spp. and 10 strains of Fusarium spp. via broth microdilution checkerboard technique system adapted from Clinical and Laboratory Standards Institute broth microdilution method M38-A2. INK128 alone was inactive against all isolates tested. However, favorable synergistic effects between INK128 and voriconazole were observed in 61% Exophiala strains and 60% Fusarium strains, despite Fusarium strains exhibited high MIC values (4–8 μg/ml) against voriconazole. In addition, synergistic effects of INK128/itraconazole were shown in 33% Exophiala strains and 30% Fusarium strains, while synergy of INK128/posaconazole were observed in 28% Exophiala strains and 30% Fusarium strains. The effective working ranges of INK128 were 0.125–2 μg/ml and 1–4 μg/ml against Exophiala isolates and Fusarium isolates, respectively. No synergistic effect was observed when INK128 was combined with amphotericin B. No antagonism was observed in all combinations. In conclusion, INK128 could enhance the in vitro antifungal activity of voriconazole, itraconazole and posaconazole against Exophiala spp. and Fusarium spp., suggesting that azoles, especially voriconazole, combined with TOR kinase inhibitor might provide a potential strategy to the treatment of Exophiala and Fusarium infections. However, further investigations are warranted to elucidate the underlying mechanism and to determine possible reliable and safe application in clinical practice.

The Transcriptome of Exophiala dermatitidis during Ex-vivo Skin Model Infection

The black yeast Exophiala dermatitidis is a widespread polyextremophile and human pathogen, that is found in extreme natural habitats and man-made environments such as dishwashers. It can cause various diseases ranging from phaeohyphomycosis and systemic infections, with fatality rates reaching 40%. While the number of cases in immunocompromised patients are increasing, knowledge of the infections, virulence factors and host response is still scarce. In this study, for the first time, an artificial infection of an ex-vivo skin model with Exophiala dermatitidis was monitored microscopically and transcriptomically. Results show that Exophiala dermatitidis is able to actively grow and penetrate the skin. The analysis of the genomic and RNA-sequencing data delivers a rich and complex transcriptome where circular RNAs, fusion transcripts, long non-coding RNAs and antisense transcripts are found. Changes in transcription strongly affect pathways related to nutrients acquisition, energy metabolism, cell wall, morphological switch, and known virulence factors. The L-Tyrosine melanin pathway is specifically upregulated during infection. Moreover the production of secondary metabolites, especially alkaloids, is increased. Our study is the first that gives an insight into the complexity of the transcriptome of Exophiala dermatitidis during artificial skin infections and reveals new virulence factors.

Evaluation of the Effects of Photodynamic Therapy Alone and Combined with Standard Antifungal Therapy on Planktonic Cells and Biofilms of Fusarium spp. and Exophiala spp

Infections of Fusarium spp. and Exophiala spp. are often chronic, recalcitrant, resulting in significant morbidity, causing discomfort, disfigurement, social isolation. Systemic disseminations happen in compromised patients, which are often refractory to available antifungal therapies and thereby lead to death. The antimicrobial photodynamic therapy (aPDT) has been demonstrated to effectively inactivate multiple pathogenic fungi and is considered as a promising alternative treatment for mycoses. In the present study, we applied methylene blue (8, 16, and 32 μg/ml) as a photosensitizing agent and light emitting diode (635 ± 10 nm, 12 and 24 J/cm²), and evaluated the effects of photodynamic inactivation on five strains of Fusarium spp. and five strains of Exophiala spp., as well as photodynamic effects on in vitro susceptibility to itraconazole, voriconazole, posaconazole and amphotericin B, both planktonic and biofilm forms. Photodynamic therapy was efficient in reducing the growth of all strains tested, exhibiting colony forming unit-reductions of up to 6.4 log₁₀ and 5.6 log₁₀ against planktonic cultures and biofilms, respectively. However, biofilms were less sensitive since the irradiation time was twice longer than that of planktonic cultures. Notably, the photodynamic effects against Fusarium strains with high minimal inhibitory concentration (MIC) values of ≥16, 4-8, 4-8, and 2-4 μg/ml for itraconazole, voriconazole, posaconazole and amphotericin B, respectively, were comparable or even superior to Exophiala spp., despite Exophiala spp. showed relatively better antifungal susceptibility profile. MIC ranges against planktonic cells of both species were up to 64 times lower after aPDT treatment. Biofilms of both species showed high sessile MIC50 (SMIC50) and SMIC80 of ≥16 μg/ml for all azoles tested and variable susceptibilities to amphotericin B, with SMIC ranging between 1 and 16 μg/ml. Biofilms subjected to aPDT exhibited a distinct reduction in SMIC50 and SMIC80 compared to untreated groups for both species, except SMIC80 of itraconazole against Fusarium biofilms. In conclusion, in vitro photodynamic therapy was efficient in inactivation of Fusarium spp. and Exophiala spp., both planktonic cultures and biofilms. In addition, the combination of aPDT and antifungal drugs represents an attractive alternative to the current antifungal strategies. However, further investigations are warranted for the reliable and safe application in clinical practice.

Phaeohyphomycosis Due to Exophiala jeanselmei: An Emerging Pathogen in India--Case Report and Review

We present a rare case of a 30-year-old woman who presented with a swelling on the lateral aspect of her left forearm, present since 6 months, adjacent to a 16-year-old burn scar. X-ray of elbow joint and forearm revealed the subcutaneous nature of the swelling. Giemsa and periodic acid-Schiff-stained smears and potassium hydroxide mount of fine-needle aspirate of the swelling revealed dematiaceous, branching, and septate fungal hyphae. Fungal culture of the aspirated pus showed growth of Exophiala jeanselmei. Histopathological examination revealed brown-coloured hyphae with foreign body giant cell reaction and palisading granulomas in the surrounding tissue. The patient was successfully treated with surgical excision of the swelling. All the cases of phaeohyphomycosis due to Exophiala spp. in India are also reviewed.

Morphological and Molecular Characterization of Exophiala polymorpha sp. nov. Isolated from Sporotrichoid Lymphocutaneous Lesions in a Patient with Myasthenia Gravis

Exophiala species are capable of causing cutaneous and subcutaneous infections in immunocompromised patients. An Exophiala isolate was cultured from a biopsy specimen of a lesion on the forearm of a patient with myasthenia gravis. The patient also had lesions on the palm and distal aspects of the hand, which were successfully treated with a long-term course of itraconazole. A detailed morphological and molecular characterization of the isolate was undertaken. Phylogenetic analysis of the internal transcribed spacer region and portions of the β-tubulin and translation elongation factor 1-alpha genes indicated that the isolate was a novel species closely related to but genetically distinct from species within the Exophiala spinifera clade; the name Exophiala polymorpha sp. nov. is proposed. Morphologically, E. polymorpha most closely resembles E. xenobiotica but it differs in possessing phialides bearing prominent, wide collarettes, and it does not produce chlamydospores.

Antifungal susceptibility and phenotypic characterization of oral isolates of a black fungus from a nasopharyngeal carcinoma patient under radiotherapy

Background

During a research project on fungal Candida species in patients wearing obturator treated with radiotherapy for their recurrent nasopharyngeal carcinoma, we serendipitously observed the presence of black fungus in two consecutive samples from a patient.

Case presentation

The samples were collected from a 57 year-old Hong Kong gentleman who diagnosed to have undifferentiated type of nasopharyngeal carcinoma. He was treated with definitive concurrent chemoradiotherapy followed by adjuvant chemotherapy and then received a second-course radiotherapy with IMRT. 18S rDNA sequencing revealed that the isolates belong to Exophiala dermatitidis which was susceptible to fluconazole, itraconazole, ketoconazole and voriconazole. Interestingly, E. dermatitidis isolates were resistant to caspofungin and one isolate was resistant to amphotericin B. Both isolates formed biofilms comparable to that of Candida albicans. Single isolate of E. dermatitidis showed hemolysin and proteinase ability comparable to C. albicans whilst the other isolate was not.

Conclusion

We, for the first time, reported the discovery of a black fungus–E. dermatitidis isolates derived from a patient with nasopharyngeal carcinoma treated with radiotherapy. These isolates were shown to be resistant to caspofungin, a major antifungal agent for systemic candidiasis. As little is known about the black fungus in the clinical setting, it is important that clinicians must keep abreast of the new discovery in this field.

Inherited CARD9 deficiency in 2 unrelated patients with invasive Exophiala infection

BACKGROUND

Exophiala species are mostly responsible for skin infections. Invasive Exophiala dermatitidis disease is a rare and frequently fatal infection, with 42 cases reported. About half of these cases had no known risk factors. Similarly, invasive Exophiala spinifera disease is extremely rare, with only 3 cases reported, all in patients with no known immunodeficiency. Autosomal recessive CARD9 deficiency has recently been reported in otherwise healthy patients with severe fungal diseases caused by Candida species, dermatophytes, or Phialophora verrucosa.

METHODS

We investigated an 8-year-old girl from a nonconsanguineous Angolan kindred, who was born in France and developed disseminated E. dermatitidis disease and a 26 year-old woman from an Iranian consaguineous kindred, who was living in Iran and developed disseminated E. spinifera disease. Both patients were otherwise healthy.

RESULTS

We sequenced CARD9 and found both patients to be homozygous for loss-of-function mutations (R18W and E323del). The first patient had segmental uniparental disomy of chromosome 9, carrying 2 copies of the maternal CARD9 mutated allele.

CONCLUSIONS

These are the first 2 patients with inherited CARD9 deficiency and invasive Exophiala disease to be described. CARD9 deficiency should thus be considered in patients with unexplained invasive Exophiala species disease, even in the absence of other infections.

Emerging pathogen in immunocompromised hosts: Exophiala dermatitidis mycosis in graft-versus-host disease

Infection with the dematiaceous environmental fungus Exophiala, an emerging pathogen in immunocompromised individuals, poses a diagnostic and therapeutic challenge. Herein, we report the first Exophiala dermatitidis fungemia case, to our knowledge, in an allogeneic hematopoietic stem cell transplant patient with graft-versus-host disease, expanding the clinical setting where Exophiala species mycosis should be suspected.