Isavuconazole: A New Broad-Spectrum Triazole Antifungal Agent

Cutaneous Fungal Masses From Prior Environmental Injury Following Kidney Transplant: A Case Report

Fungus account for ∼ 5% of all cases infections following solid organ transplant. Fungal infections in the setting of immunosuppression may progress rapidly and present in an atypical pattern. Herein we describe 4 cases of environmental fungal infections acquired decades prior to transplant that developed into localized atypical cutaneous masses following kidney transplant.

Trends in antifungal use in US hospitals, 2006-12

Background

Although trends in antibiotic use have been characterized, less is known about antifungal use. Data on antifungal use are important for understanding practice patterns, assessing emergence of antifungal resistance and developing antifungal stewardship programmes. We estimated national trends in inpatient antifungal use in the USA.

Methods

Using billing data for antifungals from the Truven Health MarketScan® Hospital Drug Database during 2006-12, we estimated the proportion of discharges at which antifungals were given and days of therapy (DOT)/1000 patient days (PDs) by antifungal drug type, year, patient and facility characteristics. We created national estimates using weights generated from Centers for Medicare and Medicaid Services data and assessed trends over time.

Results

Overall, 2.7% of all inpatients and 7.7% of those in ICUs received antifungals. The estimated DOT/1000 PDs for any antifungal was 35.0 for all inpatients and 73.7 for ICU patients. Azoles accounted for 80% of all antifungal use (28.5/1000 PDs), followed by echinocandins (5.0/1000 PDs). By multivariable trend analysis, DOT/1000 PDs for azoles (-21%) and polyenes (-47%) decreased between 2006 and 2012, whereas echinocandins increased 11% during 2006-10 and declined after 2011. Unspecified septicaemia, HIV and antineoplastic therapy were among the top primary diagnosis codes for patients who received antifungals.

Conclusions

Antifungals were most frequently used in ICU settings and fluconazole accounted for a large, but declining, proportion of antifungal use. Antifungal stewardship efforts may have the most impact if focused in ICUs, among certain patient groups (e.g. HIV and malignancy) and on stopping empirical antifungal therapy for unspecified sepsis when not indicated.

Pediatric Mucormycosis: A 10-Year Systematic Review of Reported Cases and Review of the Literature

Mucormycosis is a severe infection that affects a variety of patients, including immunocompromised children and neonates. Given improved survival rates from advances in the treatment of malignancies, the population at risk for mucormycosis is increasing. We conducted a systematic review of cases of mucormycosis in children in the English-language literature reported between August 2008 and June 2017 and analyzed the clinical characteristics, diagnosis, management, and outcome of those infections. The most common underlying diagnoses included neutropenia (41%), hematologic malignancy (39%), prematurity (13%), and hematopoietic stem cell transplant (11%). Sinus disease (28%) and disseminated disease (24%) were the most common presentations. Rhizopus spp were the most common organisms isolated (22%). Amphotericin B remains the backbone of treatment and was prescribed in 86% of these cases. The resulting mortality rate remains high (32%). We provide here the results of a literature review of mucormycosis in children, including its epidemiology and clinical manifestations, and describe current advances in its diagnosis and treatment.

Pharmacokinetics and Dialytic Clearance of Isavuconazole During In Vitro and In Vivo Continuous Renal Replacement Therapy

The pharmacokinetics (PK) and dialytic clearance of isavuconazole in vitro and in 7 solid organ transplant patients undergoing continuous renal replacement therapy (CRRT) were evaluated. In vivo, mean (± SD) plasma PK parameters of isavuconazole were: C _max 4.00±1.45 mg/L, C _min 1.76±0.76 mg/L, t _½ 48.36±29.78 h, V_ss 288.78±182.11 L, CL_ss 4.85±3.79 L/h, and AUC 54.01±20.98 mg ⋅ h/L. Transmembrane clearance represented just 0.7% of the total isavuconazole clearance. These data suggest that isavuconazole is not readily removed by CRRT and no dose adjustments are necessary.

Evaluation of the effect of 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol in comparison with metronidazole in an in vitro culture of Blastocystis in samples of patients with irritable bowel syndrome

Metronidazole is the most-used pharmaceutical for the treatment of infection by Blastocystis. However, studies have reported resistance of the microorganism towards this pharmaceutical. In Mexico, studies concerning the prevalence of this parasite and its relationship to Irritable Bowel Syndrome have been carried out. To evaluate the in vitro effect of metronidazole and the compound 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol over Blastocystis, as well as the prevalence of Blastocystis in patients with Irritable Bowel Syndrome. A prospective, transversal design study (April 2016-April 2017) of 51 samples of patients with Irritable Bowel Syndrome, obtained from the ISSEMyM Medical Center in Toluca, Mexico. For the identification of Blastocystis was done in three serial stool samples through direct microscopic examination and the Ritchie technique. The in vitro susceptibility test towards metronidazole and the triazolic compound was done through a microculture in concentrations of 1 to 1000 µg/mL, each one in triplicate. A 31.3% prevalence of Blastocystis was observed in the population, with greater prevalence in women (30.2%) than in men (25%). In the susceptibility test, a CL50 of 64 µg/mL was obtained for metronidazole, in comparison to the CL50 of 250 µg/mL for 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol. This molecule in development has an effect for the treatment of infection by Blastocystis in vitro in patients with IBS and therefore, more studies should be performed.

Treatment Failure of Isavuconazole in a Patient with Cryptococcosis

Isavuconazole is a broad-spectrum azole that is FDA-approved for the treatment of aspergillosis and mucormycosis; data on the use of isavuconazole for the treatment and prevention of other invasive fungal infections are limited. Here, we report a patient with pulmonary cryptococcosis treated with isavuconazole who experienced progression to disseminated infection with Cryptococcus while on isavuconazole. Caution is advised when using isavuconazole in situations where there is a paucity of data to recommend its use.

Disseminated cerebral aspergillosis complicated by thrombotic microangiopathy

Invasive aspergillosis (IA) is a serious condition that can affect almost any organ. Cerebral aspergillosis itself is rapidly fatal without treatment. We report a case of disseminated cerebral IA in a patient exposed to cyclophosphamide, rituximab and prednisone. This case is unique because: 1) disseminated IA has not been described in anti-glomerular basement membrane glomerulonephritis; 2) IA led to thrombotic microangiopathy with normal ADAMTS13 and 3) voriconazole toxicity necessitated use of isavuconazole for IA treatment.

Isavuconazole and voriconazole inhibition of sterol 14α-demethylases (CYP51) from Aspergillus fumigatus and Homo sapiens

Here we report the first evaluation of isavuconazole inhibition of Aspergillus fumigatus CYP51 and thus sterol biosynthesis in the fungus. Voriconazole and isavuconazole both bound tightly to recombinant A. fumigatus CYP51 isoenzymes A and B (AfCYP51A and AfCYP51B) isolated in Escherichia coli membranes. CYP51 reconstitution assays confirmed that AfCYP51A and AfCYP51B as well as three AfCYP51A mutants known to confer azole resistance (G54W, L98H and M220K) were strongly inhibited by both triazoles. Voriconazole bound relatively weakly to purified Homo sapiens CYP51 (HsCYP51), unlike isavuconazole that bound tightly. However, isavuconazole was a relatively poor inhibitor of HsCYP51 activity, with an IC₅₀ value (half-maximal inhibitory concentration) of 25 µM, which was 55- to 120-fold greater than those observed for the A. fumigatus CYP51 enzymes, albeit not as poor an inhibitor of HsCYP51 as voriconazole with an IC₅₀ value of 112 µM. Sterol analysis of triazole-treated A. fumigatus Af293 cells confirmed that isavuconazole and voriconazole both inhibited cellular CYP51 activity with the accumulation of 14-methylated sterol substrates and depletion of ergosterol levels. Isavuconazole elicited a stronger perturbation of the sterol composition in A. fumigatus Af293 than voriconazole at 0.0125 µg/mL, indicating increased potency. However, complementation studies in Saccharomyces cerevisiae using strains containing AfCYP51A and AfCYP51B showed isavuconazole to be equally as effective at inhibiting CYP51 activity as voriconazole. These in vitro studies suggest that isavuconazole is an effective alternative to voriconazole as an antifungal agent against the target CYP51 in A. fumigatus.

Rhinoorbital mucormycosis in the immunocompetent: Experience with Isavuconazole

Mucormycosis is a severe opportunistic fungal infection caused by Mucorales. The majority of the affected patients have a history of immunosuppression, with a reported incidence of 4-19% in the immunocompetent. Early recognition and diagnosis, combined with surgical debridement and appropriate antifungal therapy are essential to achieve a cure. In this article we report the case of a 61-year-old immunocompetent male who complained with pain in his right eye. After being first diagnosed with conjunctivitis and treated accordingly, he eventually needed surgical debridement and the biopsy showed the presence of fungi of the class Zygomycetes. He was submitted to intravenous therapy with Liposomal Amphotericin B (LAmB) and Posaconazole for several days, which was then changed to Isavuconazole due to bicytopenia. He also received treatment with hyperbaric oxygen, achieving altogether good results. He was discharged after eight months, still on oral Isavuconazole 200mg/day and re-evaluated after three and six months, showing no evidence of progression of the infection.

[Invasive aspergillosis in critically ill patients]

Critically ill patients without severe immunosuppression make up a population in which invasive aspergillosis (IA) has been identified as an emergent pathology. Chronic treatment with corticosteroids, chronic obstructive pulmonary disease, and liver cirrhosis are repeatedly identified risk factors. However, due to the non-specificity of the symptoms and signs in the critical patient, and the relative low diagnostic capacity of the complementary tests, the diagnosis of the IA is a challenge for the specialist in critical care medicine. The application of diagnostic algorithms adapted to critical patients, in whom activation will depend on the isolation of Aspergillus in a respiratory specimen, is the most efficient diagnostic methodology in this population. Among the diagnostic approaches, the determination of galactomannan in bronchoalveolar fluid is the most useful diagnostic test. Once the suspicion is established, treatment should be started as soon as possible. Voriconazole, amphotericin B, and isavuconazole are the most effective treatments. Although voriconazole and amphotericin B are the drugs with the most scientific evidence, they are related with adverse effects and pharmacokinetic difficulties. Therefore, isavuconazole, which has shown high efficacy and safety in other populations, is a potential alternative of great interest for critically ill patients.

Tissue Distribution and Penetration of Isavuconazole at the Site of Infection in Experimental Invasive Aspergillosis in Mice with Underlying Chronic Granulomatous Disease

Isavuconazole, the active moiety of the prodrug isavuconazonium sulfate, has potent activity against a wide spectrum of fungal pathogens and is approved for the treatment of invasive aspergillosis, yet little is known about the tissue penetration of isavuconazole at the target sites of infection. Here, we explored the spatial and quantitative distribution of isavuconazole in tissue lesions in experimental pulmonary aspergillosis established in mice with chronic granulomatous disease (CGD) (gp91^phox-). Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and laser capture microdissection (LCM)-directed high-pressure liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) were used to analyze infected lungs and brain tissues collected 1, 3, 6, and 24 h after a single oral administration of the prodrug at a dose of 256 mg/kg of body weight (corresponding to 122.9 mg/kg of isavuconazole). Drug enrichment within granulomatous lesions was observed in lung tissue at 1 h postdose, although drug levels quickly equilibrated afterwards between lesion and nonlesion areas. A prominent antifungal effect in the infected lung tissue was revealed by histopathological analysis. Isavuconazole also penetrated into the brain with high efficiency. These data further support the value of isavuconazole to treat patients with invasive aspergillosis.

No Dose Adjustment for Isavuconazole Based on Age or Sex

This phase 1, open-label, single-dose, parallel-group study evaluated the pharmacokinetics (PK) of isavuconazole after a single oral dose of the prodrug isavuconazonium sulfate in healthy nonelderly (age, 18 to 45 years) and elderly (age, ≥65 years) males and females. Overall, 48 subjects were enrolled in the study (n = 12 each in groups of nonelderly males and females and elderly males and females).

This phase 1, open-label, single-dose, parallel-group study evaluated the pharmacokinetics (PK) of isavuconazole after a single oral dose of the prodrug isavuconazonium sulfate in healthy nonelderly (age, 18 to 45 years) and elderly (age, ≥65 years) males and females. Overall, 48 subjects were enrolled in the study (n = 12 each in groups of nonelderly males and females and elderly males and females). All subjects received a single oral dose of 372 mg of isavuconazonium sulfate (equivalent to 200 mg isavuconazole). PK samples were collected for analysis of isavuconazole plasma concentrations from the predose time point up to 336 h postdose. Data were analyzed using population pharmacokinetic (PPK) analysis. The resulting PPK model included two compartments with Weibull absorption function as well as interindividual variability with respect to clearance, intercompartment clearance, volumes of central and peripheral compartments, and two Weibull absorption parameters, RA and KAMAX. The PPK analysis showed that elderly females had the highest exposure versus males (ratio of total area under the time-concentration curve [AUC], 138; 90% confidence interval [CI], 118 to 161) and versus nonelderly females (ratio of AUC, 147; 90% CI, 123 to 176). Higher exposures in elderly females were not associated with significant toxicity or treatment-emergent adverse events, as measured in this study. No dose adjustments appear to be necessary based on either age group or sex even with an increase in exposure for elderly females. (This study has been registered at ClinicalTrials.gov under registration no. NCT01657890.)

Antifungal Resistance in Clinical Isolates of Aspergillus spp.: When Local Epidemiology Breaks the Norm

Aspergillosis is a set of very frequent and widely distributed opportunistic diseases. Azoles are the first choice for most clinical forms. However, the distribution of azole-resistant strains is not well known around the world, especially in developing countries. The aim of our study was to determine the proportion of non-wild type strains among the clinical isolates of Aspergillus spp. To this end, the minimum inhibitory concentration of three azoles and amphotericin B (used occasionally in severe forms) was studied by broth microdilution. Unexpectedly, it was found that 8.1% of the isolates studied have a diminished susceptibility to itraconazole. This value turned out to be similar to the highest azole resistance rate reported in different countries across the world.

Evaluation of isavuconazole MIC strips for susceptibility testing of Aspergillus and Scedosporium species

Isavuconazole is a new triazole with an expanded-spectrum and potent activity against moulds and yeasts. It has been authorized for use in adults for the treatment of invasive aspergillosis and for mucormycosis. The only commercially available isavuconazole susceptibility test is the minimum inhibitory concentration (MIC) strip isavuconazole test. The objective of this study was to assess the in vitro activity of isavuconazole using gradient concentration MIC strips, compared with the EUCAST broth microdilution reference method. A total of 147 clinically relevant fungal isolates comprising 120 Aspergillus sp. and 27 Scedosporium apiospermum complex were tested for susceptibility to isavuconazole using the EUCAST broth microdilution method and by the MIC strip isavuconazole test. The percent essential agreement between the two methods was calculated within a 1-fold dilution. The geometric means for the MICs using the EUCAST reference methods and the strip test were respectively: 0.60 mg/l and 0.65 mg/l for A. fumigatus, 0.70 mg/l and 0.77 mg/l for A. flavus, 1.50 mg/l and 1.25 mg/l for A. niger, 0.41 mg/l and 0.38 mg/l for A. terreus, 1.22 mg/l and 1.08 mg/l for S. apiospermum complex. The isavuconazole MIC strips showed good agreement with the EUCAST reference method. Isavuconazole MIC strips could be useful for susceptibility testing of Aspergillus sp. and S. apiospermum complex.

Drugs in Clinical Development for Fungal Infections

Despite increasing rates of invasive fungal infections being reported globally, only a single antifungal drug has been approved during the last decade. Resistance, toxicity, drug interactions and restricted routes of administration remain unresolved issues. This review focuses on new antifungal compounds which are currently in various clinical phases of development. We discuss two azoles with a tetrazole moiety that allows selective activity against the fungal CYP: VT-1161 for Candida infections and VT-1129 for cryptococcal meningoencephalitis. We also discuss two glucan synthesis inhibitors: CD101, an echinocandin with an increased half-life, and SCY-078 with oral bioavailability and increased activity against echinocandin-resistant isolates. Among the polyenes, we discuss MAT023, an encochleated amphotericin B formulation that allows oral administration. Two novel classes of antifungal drugs are also described: glycosylphosphatidylinositol inhibitors, and the leading drug APX001, which disrupt the integrity of the fungal wall; and the orotomides, inhibitors of pyrimidine synthesis with the leading drug F901318. Finally, a chitin synthesis inhibitor and progress on human monoclonal antifungal antibodies are discussed.

Phaeohyphomycosis caused by Medicopsis romeroi in solid organ transplant recipients: Report of two cases and comprehensive review of the literature

Medicopsis romeroi is a melanized coelomycetous fungus, mainly found in tropical and subtropical regions and an uncommon cause of infection in solid organ transplant (SOT) recipients. We describe two cases of SOT recipients diagnosed with phaeohyphomycosis due to M romeroi and provide a comprehensive literature review. These infections should be considered in patients native to tropical countries with a localized skin and soft tissue infection. Sequencing is needed for accurate identification of uncommon melanized fungi. Surgical treatment is recommended to cure the infection and co-adjunctive oral antifungals should be considered.

Fungal Lanosterol 14α-demethylase: A target for next-generation antifungal design

The cytochrome P450 enzyme lanosterol 14α-demethylase (LDM) is the target of the azole antifungals used widely in medicine and agriculture as prophylaxis or treatments of infections or diseases caused by fungal pathogens. These drugs and agrochemicals contain an imidazole, triazole or tetrazole substituent, with one of the nitrogens in the azole ring coordinating as the sixth axial ligand to the LDM heme iron. Structural studies show that this membrane bound enzyme contains a relatively rigid ligand binding pocket comprised of a deeply buried heme-containing active site together with a substrate entry channel and putative product exit channel that reach to the membrane. Within the ligand binding pocket the azole antifungals have additional affinity determining interactions with hydrophobic side-chains, the polypeptide backbone and via water-mediated hydrogen bond networks. This review will describe the tools that can be used to identify and characterise the next generation of antifungals targeting LDM, with the goal of obtaining highly potent broad-spectrum fungicides that will be able to avoid target and drug efflux mediated antifungal resistance.

Can Saccharomyces cerevisiae keep up as a model system in fungal azole susceptibility research?

The difficulty of manipulation and limited availability of genetic tools for use in many pathogenic fungi hamper fast and adequate investigation of cellular metabolism and consequent possibilities for antifungal therapies. S. cerevisiae is a model organism that is used to study many eukaryotic systems. In this review, we analyse the potency and relevance of this model system in investigating fungal susceptibility to azole drugs. Although many of the concepts apply to multiple pathogenic fungi, for the sake of simplicity, we will focus on the validity of using S. cerevisiae as a model organism for two Candida species, C. albicans and C. glabrata. Apart from the general benefits, we explore how S. cerevisiae can specifically be used to improve our knowledge on azole drug resistance and enables fast and efficient screening for novel drug targets in combinatorial therapy. We consider the shortcomings of the model system, yet conclude that it is still opportune to use S. cerevisiae as a model system for pathogenic fungi in this era.

Invasive Aspergillosis in Pediatric Leukemia Patients: Prevention and Treatment

The purpose of this article is to review and update the strategies for prevention and treatment of invasive aspergillosis (IA) in pediatric patients with leukemia and in patients with hematopoietic stem cell transplantation. The major risk factors associated with IA will be described since their recognition constitutes the first step of prevention. The latter is further analyzed into chemoprophylaxis and non-pharmacologic approaches. Triazoles are the mainstay of anti-fungal prophylaxis while the other measures revolve around reducing exposure to mold spores. Three levels of treatment have been identified: (a) empiric, (b) pre-emptive, and (c) targeted treatment. Empiric is initiated in febrile neutropenic patients and uses mainly caspofungin and liposomal amphotericin B (LAMB). Pre-emptive is a diagnostic driven approach attempting to reduce unnecessary use of anti-fungals. Treatment targeted at proven or probable IA is age-dependent, with voriconazole and LAMB being the cornerstones in >2yrs and <2yrs age groups, respectively.

Resistance mechanism and proteins in Aspergillus species against antifungal agents

Aspergillus

species contain pathogenic and opportunistic fungal pathogens which have the potential to cause mycosis (invasive aspergillosis) in humans. The existing antifungal drugs have limitation largely due to the development of drug-resistant isolates. To gain insight into the mechanism of action and antifungal drug resistance in Aspergillus species including biofilm formation, we have reviewed protein data of Aspergillus species during interaction with antifungals drugs (polynes, azoles and echinocandin) and phytochemicals (artemisinin, coumarin and quercetin). Our analyses provided a list of Aspergillus proteins (72 proteins) that were abundant during interaction with different antifungal agents. On the other hand, there are 26 proteins, expression level of which is affected by more than two antifungal agents, suggesting the more general response to the stress induced by the antifungal agents. Our analysis showed enzymes from cell wall remodelling, oxidative stress response and energy metabolism are the responsible factors for providing resistance against antifungal drugs in Aspergillus species and could be explored further in clinical isolates. Also, these findings have clinical importance since the effect of drug targeting different proteins can be potentiated by combination therapy. We have also discussed the opportunities ahead to study the functional role of proteins from environmental and clinical isolates of Aspergillus during its interaction with the antifungal drugs.

Abbreviations

IPA: invasive pulmonary aspergillosis; IA: invasive aspergillosis; AmB: Amphotericin B; CAS: Caspofungin; VRC: Voriconazole; ITC: Itraconazole; POS: Posaconazole; ART: Artemisinin; QRT: Quercetin; CMR: Coumarin; MIC: minimal inhibitory concentration

Tolerability profile of the current antifungal armoury

The tolerability of available antifungal agents is essential to the final outcome of the management of invasive mycoses. There are limited classes of antifungal agents for use, and they can have serious direct toxicities and/or drug-drug interactions. In this review, we examine the common toxicities noted for antifungal agents and attempt to both identify the issues around the adverse events and provide clinical context for their occurrence in these fragile patients.

Advances in pediatric antimicrobial agents development

PURPOSE OF REVIEW

Rising rates of multidrug-resistant organisms has necessitated the development of novel antimicrobials. In this review, we will highlight agents that have recently received licensure and those that are in clinical development.

RECENT FINDINGS

In recent years, development of novel antimicrobial agents has accelerated. Although most studies have targeted the adult population, studies in pediatric patients are underway. Adequately powered clinical trials are needed to establish the safety and role of these new drugs.

SUMMARY

The recent development of novel antimicrobials to combat multidrug-resistant organisms is encouraging; however, more studies in the pediatric population are needed.

Therapeutic drug concentrations of isavuconazole following the administration of isavuconazonium sulfate capsules via gastro-jejunum tube: A case report

Invasive fungal infections are a common complication in immunocompromised patients, such as organ transplant recipients. Isavuconazole is a broad-spectrum azole antifungal for the treatment of aspergillosis and mucormycosis. The package insert for isavuconazole recommends against opening the capsule for administration through enteral feeding tubes. We describe the case of a 68-year-old man with a complex post-lung transplant course receiving isavuconazole for presumed invasive aspergillosis (bronchial alveolar lavage galactomannan index of >3.75) therapy administered through a gastrostomy-jejunostomy tube (G-J tube). Therapeutic drug monitoring was performed to ensure appropriate absorption. Peak and trough concentrations were measured in the early and late phases of the treatment course and resulted in trough levels of 2.7 mcg/mL and 4.0 mcg/mL, which is consistent with previously published trough concentrations of isavuconazole when the capsule was administered intact. This case report suggests that opening isavuconazole capsules and administration through a G-J tube results in appropriate absorption and serum drug levels comparable to intact capsules.

Advances in antifungal drug measurement by liquid chromatography-mass spectrometry

Fungal infections, especially invasive types, have become a serious healthcare problem as the immunocompromised population increases. There are five main classes of antifungal drugs: polyenes, flucytosine, allylamines, azoles, and echinocandins. Therapeutic drug monitoring (TDM) is justified for flucytosine and triazoles due to their large inter- and intra-individual pharmacokinetic variability and their high tendency for drug-drug interactions. Available methods for measuring these drugs include bioassay, liquid chromatography and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The LC-MS/MS approach is preferred due to its superior analytic sensitivity and specificity. In this review, we highlight TDM methods by LC-MS/MS for these antifungal drugs searchable in PubMed by December 1, 2018. LC-MS/MS methods that were developed for other purposes such as pharmacokinetics or toxicokinetics were also included. We have critically analyzed these methods with an emphasis on sensitivity, specificity, simplicity, throughput and robustness.

In Vitro and In Vivo Evaluation of Voriconazole-Containing Antifungal Combinations against Mucorales Using a Galleria mellonella Model of Mucormycosis

Mucorales are resistant to most antifungals. Mucormycosis associated mortality is unacceptable and new treatment approaches are needed. The objectives of this work were (i) to evaluate the nature and intensity of the in vitro effect of three drugs combinations which included voriconazole (plus amphotericin B, posaconazole and caspofungin) against 25 strains of six different Mucorales species; (ii) to evaluate a Galleria mellonella mucormycosis model; and (iii) to establish if any in vitro⁻in vivo correlation exists. As expected, amphotericin B and posaconazole were the most active drugs when tested alone. However, species-specific differences were found. The ΣFICs varied according to the used combination. Only five strains showed synergism when voriconazole was combined with posaconazole and three strains when combined with amphotericin B. Microscopic hyphae alteration were observed for some isolates when confronted against drugs combinations. Using a Galleria mellonella mucormycosis model, better survival was seen in voriconazole plus amphotericin B and plus caspofungin combined treatments when compared with AMB alone for R. microsporus. These survival improvements were obtained using a 32-fold lower amphotericin B doses when combined with VRC than when treated with the polyene alone. These lower antifungal doses emulate the antifungal concentrations where the microscopic hyphae alterations were seen.

Severe Gastric Mycormycosis Infection Followed by Cytomegalovirus Pneumonia in a Renal Transplant Recipient: A Case Report and Concise Review of the Literature

Mucormycosis is an uncommonly encountered fungal infection in solid-organ transplantation, occurring most often gastrointestinally. The most common and fatal infectious disease is cytomegalovirus (CMV) pneumonia, which may result in acute respiratory distress syndrome (ARDS), with rapid onset. Early diagnosis, active treatment, and rational reduction of immunosuppressants are crucial for successful kidney transplantation. We performed successful treatment for both mucormycosis and CMV pneumonia and adjusted the tacrolimus dose accordingly. The case we describe was that of a 47-year-old woman with history of renal transplantation 1 month earlier. She presented with chest pain and gastrointestinal bleeding and was diagnosed with gastric mucormycosis and a secondary episode of hospital-acquired pneumonia. Preemptive therapy, which included liposomal amphotericin B and posaconazole, was adminstered when voriconazole proved to be unhelpful and before histologic reports of gastric mucormycosis. Moreover, CMV re-activation was confirmed by CMV antibody detection, and we administered gancyclovir and thymosin α1 but reduced the strength of the immunosuppressive drugs. Fourteen days after the aforementioned therapy, the patient began to recover and she was discharged on day 81 postoperatively. We conclude that preemptive treatment is critical for severe infection in renal transplant recipients, especially with the rarely seen gastric mucormycosis and with ARDS. In addition, immunoregulated agents, such as asthymosin α1, are also of great value in renal transplant recipients in the setting of opportunistic pathogen infections.

Mold Infections in Solid Organ Transplant Recipients

Mold infections carry a substantial clinical and economic burden in solid organ transplant (SOT) recipients with a high overall mortality of near 30%. The most important pathogens include Aspergillus, the Zygomycetes, Fusarium, Scedosporium/Pseudallescheria, and the dematiaceous (dark) molds. Risk factors for the infections vary by transplant type but include degree of immune suppression and loss of skin or mucosal integrity. Correct diagnosis usually requires histopathology and/or culture. Management often requires a multidisciplinary team approach with combined antifungal and surgical therapies. This article reviews the epidemiology, risk factors, microbiology, diagnostic, and treatment approach to mold infections in SOT recipients.

[Invasive aspergillosis in solid organ transplantation]

Solid organ transplant (SOT) recipients have a high risk for developing invasive fungal infections (IFI). Treatment is difficult due to the interaction between the antifungal and immunosuppressant drugs, as well as the risk of hepatotoxicity and kidney failure associated with voriconazole and amphotericinB, respectively. Isavuconazole is a new antifungal triazole agent with excellent oral bioavailability, predictable and linear pharmacokinetics, good tolerance and low adverse effects. It has been approved for the treatment of invasive aspergillosis and mucormycosis. A review is presented of the reported experience in the use of isavuconazole in SOT. According to the published studies, isavuconazole has a significantly lower risk of interaction with tacrolimus, and is less hepatotoxic than voriconazole. Nevertheless, there is a significant variability between patients, and between each type of SOT. Isavuconazole reduces the side effects associated with the treatment of IFI in SOT. It would be of great interest the implementation of future clinical trials with isavuconazole for the treatment and/or prophylaxis of IFI in these patients.

Isavuconazole for Treatment of Experimental Fungal Endophthalmitis Caused by Aspergillus fumigatus

Fungal endophthalmitis remains a significant cause of vision impairment and blindness. Moreover, the prognosis is poor, in part due to delay in diagnosis and to limited availability of effective antifungal agents with good ocular penetration. Thus, it is imperative to evaluate the therapeutic efficacy in fungal endophthalmitis of newer antifungal agents. In this study, we assessed the efficacy of isavuconazole in treating Aspergillus fumigatus endophthalmitis in an exogenous mouse model of the disease. Briefly, endophthalmitis was induced by intravitreal (IVT) injection of A. fumigatus spores into immunocompetent C57BL/6 (B6) mouse eyes. Mice were randomized into five groups that received isavuconazole via (i) oral gavage, (ii) IVT injections, (iii) intravenous injection, (iv) IVT injection followed by oral gavage, and (v) IVT injection followed by intravenous injection. Our data showed that isavuconazole treatment via all routes reduced fungal burden in A. fumigatus-infected eyes. This coincided with the preservation of retinal structural integrity (histology analysis) and retinal function (electroretinography [ERG] analysis), resulting in significantly improved disease outcome. Furthermore, isavuconazole treatment reduced the levels of inflammatory cytokines (tumor necrosis factor α [TNF-α], interleukin 1β [IL-1β], and IL-6) and cellular infiltration in the eyes. Notably, oral administration of isavuconazole was as effective in ameliorating endophthalmitis as intravitreal injection of the drug. Collectively, our study demonstrates that isavuconazole is effective in treating A. fumigatus endophthalmitis in mice, indicating its potential use in human ocular infections.

Advances in the Treatment of Mycoses in Pediatric Patients

The main indications for antifungal drug administration in pediatrics are reviewed as well as an update of the data of antifungal agents and antifungal policies performed. Specifically, antifungal therapy in three main areas is updated as follows: a) Prophylaxis of premature neonates against invasive candidiasis; b) management of candidemia and meningoencephalitis in neonates; and c) prophylaxis, empiric therapy, and targeted antifungal therapy in children with primary or secondary immunodeficiencies. Fluconazole remains the most frequent antifungal prophylactic agent given to high-risk neonates and children. However, the emergence of fluconazole resistance, particularly in non-albicans Candida species, should be considered during preventive or empiric therapy. In very-low birth-weight neonates, although fluconazole is used as antifungal prophylaxis in neonatal intensive care units (NICU's) with relatively high incidence of invasive candidiasis (IC), its role is under continuous debate. Amphotericin B, primarily in its liposomal formulation, remains the mainstay of therapy for treating neonatal and pediatric yeast and mold infections. Voriconazole is indicated for mold infections except for mucormycosis in children >2 years. Newer triazoles-such as posaconazole and isavuconazole-as well as echinocandins, are either licensed or under study for first-line or salvage therapy, whereas combination therapy is kept for refractory cases.

In Vitro Activity of Isavuconazole against Opportunistic Fungal Pathogens from Two Mycology Reference Laboratories

Monitoring antifungal susceptibility patterns for new and established antifungal agents seems prudent given the increasing prevalence of uncommon species associated with higher antifungal resistance. We evaluated the activity of isavuconazole against 4,856 invasive yeasts and molds collected worldwide. The 4,856 clinical fungal isolates, including 2,351 Candida species isolates, 97 non-Candida yeasts, 1,972 Aspergillus species isolates, and 361 non-Aspergillus molds, including 292 Mucorales isolates collected in 2015 to 2016, were tested using CLSI methods. The MIC values for isavuconazole versus Aspergillus ranged from 0.06 to ≥16 μg/ml. The modal MIC for isavuconazole was 0.5 μg/ml (range, 0.25 [A. nidulans and A. terreus species complex] to 4 μg/ml [A. calidoustus and A. tubingensis]). Eight A. fumigatus isolates had elevated isavuconazole MIC values at ≥8 μg/ml (non-wild type). Isavuconazole showed comparable activity to itraconazole against the Mucorales The lowest modal isavuconazole MIC values were seen for Rhizopus spp., R. arrhizus var. arrhizus, and R. microsporus (all 1 μg/ml). Candida species isolates were inhibited by ≤0.25 μg/ml of isavuconazole (range, 96.1% [C. lusitaniae] to 100.0% [C. albicans, C. dubliniensis, C. kefyr, and C. orthopsilosis]). MIC values were ≤1 μg/ml for 95.5% of C. glabrata isolates and 100.0% of C. krusei isolates. Isavuconazole was active against the non-Candida yeasts, including Cryptococcus neoformans (100.0% at ≤0.5 μg/ml). Isavuconazole exhibited excellent activity against most species of Candida and Aspergillus Isavuconazole was comparable to posaconazole and voriconazole against the less common yeasts and molds. Isavuconazole was generally less active than posaconazole and more active than voriconazole against the 292 Mucorales isolates. We confirm the potentially useful activity of isavuconazole against species of Rhizopus as determined by CLSI methods.

Sino-Orbital Fungal Infection by Tilletiopsis minor, a Rare Human Pathogen, Diagnosed by Internal Transcribed Spacer Sequencing

Orbital infection can be caused by numerous pathogens, and accurate diagnosis informs appropriate therapy. The authors report a case of a 78-year-old man with well-controlled diabetes mellitus and recurrent sino-orbital infection following multiple surgical procedures with negative microbiologic results. This case presented a diagnostic and treatment challenge and was aided by the use of internal transcribed spacer sequencing for pathogen identification. The fungal pathogen, Tilletiopsis minor, has not previously been described as a human pathogen in the sinus and orbit. This report describes a novel orbital pathogen and highlights the importance of diagnostic diligence and utilizing internal transcribed spacer sequencing in the workup of atypical orbital infection.

A sensitive and validated HPLC-UV method for the quantitative determination of the new antifungal drug isavuconazole in human plasma

Isavuconazole is a broad-spectrum triazole antifungal drug recently approved for the therapy of both invasive aspergillosis and mucormycosis. To support a widespread therapeutic drug monitoring of isavuconazole, a simple, sensitive, and precise high-performance liquid chromatography method with UV detection was developed and fully validated for the quantification of this drug in human plasma. The method involved a combined protein precipitation-solid-phase extraction and a chromatographic separation on a Waters XTerra RP₁₈ (150 × 4.6 mm, 3.5 μm) column using an isocratic mobile phase of ammonium acetate buffer (pH 8.0, 10 mm) and acetonitrile (45:55, v/v). The UV detection was performed at 285 nm. This method was linear (correlation coefficients ≥0.998), specific (no interference with plasma components or various potentially co-administrated drugs), sensitive (lower limit of quantification of 0.025 μg/mL), reproducible (coefficients of variation were ≤7.9%) and accurate (deviations ranged from -5.0 to 8.0%) over the range of 0.025-10 μg/mL. The method fulfilled all of the US Food and Drug Administration guidelines validation criteria and performed well in an international proficiency testing program. The assay was also successfully applied to routine therapeutic drug monitoring of patients and to drug stability investigations under various conditions.

Treatment outcomes in patients with proven/probable vs possible invasive mould disease in a phase III trial comparing isavuconazole vs voriconazole

Treatment outcomes in patients with proven/probable vs possible invasive mould disease (IMD; 2008 European Organisation for Research and Treatment of Cancer/Mycoses Study Group [EORTC/MSG] criteria) needed further assessment. The Phase III SECURE trial compared isavuconazole vs voriconazole for treatment of IMD. This post hoc analysis assessed all-cause mortality (ACM) through day 42 (primary endpoint) and day 84, overall and clinical success at end of treatment (EOT), and drug-related treatment-emergent adverse events (TEAEs) in subgroups with proven/probable or possible IMD. Of 516 randomised patients, 304 (58.9%) had proven/probable IMD and 164 (31.8%) had possible IMD as per EORTC/MSG criteria; 48 did not have IMD. Across treatment groups, day 42 and day 84 ACM were numerically lower for possible vs proven/probable IMD (day 42: 17.1% vs 21.1%; P = 0.3, day 84: 26.2% vs 32.6%; P = 0.15). Overall and clinical success at EOT were significantly higher for possible IMD compared with proven/probable IMD (48.2% vs 36.2%; P = 0.01, 75.0% vs 63.1%; P = 0.01 respectively). Fewer drug-related TEAEs were reported with isavuconazole compared with voriconazole in patients with either proven/probable or possible IMD. Compared with patients with proven/probable IMD, those with possible IMD demonstrated higher overall and clinical success rates, supporting early initiation of antifungal treatment.

Therapy of Mucormycosis

Despite the recent introduction of mold-active agents (posaconazole and isavuconazole), in addition to amphotericin B products, to our armamentarium against mucormycosis, many uncertainties remain for the management of this uncommon opportunistic infection, as there are no data from prospective randomized clinical trials to guide therapy. In this mini-review, we present the current status of treatment options. In view of the heterogeneity of the disease (different types of affected hosts, sites of infection, and infecting Mucorales), mucormycosis management requires an individualized management plan that takes into account the net state of immunosuppression of the host, including comorbidities, certainty of diagnosis, site of infection, and antifungal pharmacological properties.

Widespread Lichtheimia Infection in a Patient with Extensive Burns: Opportunities for Novel Antifungal Agents

The Mucorales fungi-formerly classified as the zygomycetes-are environmentally ubiquitous fungi, but generally rare causes of clinical infections. In the immunocompromised host, however, they can cause invasive, rapidly spreading infections that confer a high risk of morbidity and mortality, often despite surgical and antifungal therapy. Patients with extensive burn injuries are particularly susceptible to skin and soft-tissue infections with these organisms. Here, we present a case of Lichtheimia infection in a patient with extensive full-thickness burns that required significant and repeated surgical debridement successfully treated with isavuconazole and adjunctive topical amphotericin B washes. We also review the available literature on contemporary antifungal treatment for Lichtheimia species and related Mucorales fungi.

Sterol Composition of Clinically Relevant Mucorales and Changes Resulting from Posaconazole Treatment

Mucorales are fungi with increasing importance in the clinics. Infections take a rapidly progressive course resulting in high mortality rates. The ergosterol biosynthesis pathway and sterol composition are of interest, since they are targeted by currently applied antifungal drugs. Nevertheless, Mucorales often exhibit resistance to these drugs, resulting in therapeutic failure. Here, sterol patterns of six clinically relevant Mucorales (Lichtheimia corymbifera, Lichtheimia ramosa, Mucor circinelloides, Rhizomucor pusillus, Rhizopus arrhizus, and Rhizopus microsporus) were analysed in a targeted metabolomics fashion after derivatization by gas chromatography-mass spectrometry. Additionally, the effect of posaconazole (POS) treatment on the sterol pattern of R. arrhizus was evaluated. Overall, fifteen different sterols were detected with species dependent variations in the total and relative sterol amount. Sterol analysis from R. arrhizus hyphae confronted with sublethal concentrations of posaconazole revealed the accumulation of 14-methylergosta-8,24-diene-3,6-diol, which is a toxic sterol that was previously only detected in yeasts. Sterol content and composition were further compared to the well-characterized pathogenic mold Aspergillus fumigatus. This work contributes to a better understanding of the ergosterol biosynthesis pathway of Mucorales, which is essential to improve antifungal efficacy, the identification of targets for novel drug design, and to investigate the combinatorial effects of drugs targeting this pathway.

Molecular Evolution of Antifungal Drug Resistance

The fungal pathogens Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus have transitioned from a rare curiosity to a leading cause of human mortality. The management of infections caused by these organisms is intimately dependent on the efficacy of antifungal agents; however, fungi that are resistant to these treatments are regularly isolated in the clinic, impeding our ability to control infections. Given the significant impact fungal pathogens have on human health, it is imperative to understand the molecular mechanisms that govern antifungal drug resistance. This review describes our current knowledge of the mechanisms by which antifungal drug resistance evolves in experimental populations and clinical settings. We explore current antifungal treatment options and discuss promising strategies to impede the evolution of drug resistance. By tackling antifungal drug resistance as an evolutionary problem, there is potential to improve the utility of current treatments and accelerate the development of novel therapeutic strategies.

Direct in vitro comparison of the prodrug isavuconazonium sulfate with the isavuconazole active compound against Aspergillus spp. and 2 rare moulds

Isavuconazonium sulfate is a prodrug of isavuconazole, a broad-spectrum mould-active triazole antifungal drug. We provide a direct comparison of the in vitro activity of the prodrug versus the active metabolite against clinical isolates of Aspergillus spp., Sarocladium kiliense, and Scedosporium apiospermum using CLSI broth microdilution methods. The MIC values obtained for the prodrug were one 2-fold dilution higher than those of isavuconazole for all isolates tested. Using previously defined epidemiological cutoff values for isavuconazole and Aspergillus spp., 96.4% of isolates were wild type (WT) to isavuconazole and only 75% were WT to the prodrug. The essential agreement (±2 log₂ dilutions) between prodrug and isavuconazole MIC values was 96.4% across all tested isolates. The active metabolite, isavuconazole, is recommended to use during in vitro susceptibility testing of fungal isolates.

Mucormycosis: Early Identification of a Deadly Fungus [Formula: see text]

Mucormycosis is a rare invasive fungal infection that affects immunocompromised patients and is fatal when not identified and treated early. Diagnosis is often delayed as the symptoms are nonspecific and frequently mimic other common diseases. Pediatric patients with cancer are at risk for the infection; however, there is limited research that applies directly to the pediatric population. An understanding of the risk factors and clinical presentation of mucormycosis is crucial for the pediatric oncology provider to initiate the workup and provide prompt treatment. The gold standard for diagnosing mucormycosis is biopsy; however, the use of polymerase chain reaction is a novel tool that is being investigated. The mainstays of treatment are antifungal medications, surgery, and reversal of predisposing risk factors, although, new therapies are also emerging. This article will review the pathophysiology, clinical manifestations, and diagnostics of mucormycosis and will discuss current treatment and management strategies for the pediatric oncology clinician to allow for timely diagnosis and intervention to optimize patient outcomes.