Profile of isavuconazole and its potential in the treatment of severe invasive fungal infections

Case report: Successful combination therapy with isavuconazole and amphotericin B in treatment of disseminated Candida tropicalis infection

Disseminated candidiasis is a severe complication in patients with hematological malignancies who have undergone chemotherapy or hematopoietic stem cell transplantation. It has a high mortality rate. When disseminated candidiasis caused by Candida tropicalis involves either the brain or heart, the prognosis is extremely poor. Traditional methods such as cultures are limited in diagnosing disseminated candidiasis. We describe a case report of a 55-year-old man with acute myeloid leukemia who developed candidemia caused by Candida tropicalis after chemotherapy, which disseminated extensively to the heart, brain, skin, liver, spleen and kidneys. In this instance, the patient was rapidly diagnosed with candida infection by metagenomic next generation sequencing, and successfully treated with combination therapy of isavuconazole and amphotericin B. The patient continued with treatment of leukemia while simultaneously receiving antifungal therapy, and both leukemia and disseminated candidiasis were effectively controlled. This case report provides real-world experience for treatment of patients with leukemia complicated by disseminated candidiasis.

Focusing COVID-19-associated mucormycosis: a major threat to immunocompromised COVID-19

COVID-19 disease has been identified to cause remarkable increase of mucormycosis infection cases in India, with the majority of cases being observed in individuals recovering from COVID-19. Mucormycosis has emanated as an outcome of the recent COVID-19 pandemic outbreak as rapidly developing fatal illness which was acquired by Mucorales fungus which is a subcategory of molds known as mucormycetes. Mucormycosis is one of the serious, sporadic mycotic illnesses which is a great threat to immunocompromised COVID-19 patients and affects people of all ages, including children with COVID-19 infections. This is associated with tissue damaging property and, therefore, causes serious clinical complications and elevated death rate. The COVID-19-associated mucormycosis or "black fungus" are the terms used interchangeably. The rapid growth of tissue necrosis presenting as "rhino-orbital-cerebral, pulmonary, cutaneous, gastrointestinal, and disseminated disease" are various clinical forms of mucormycosis. The patient's prognosis and survival can be improved with proper surgeries using an endoscopic approach for local tissue protection in conjunction with course of appropriate conventional antifungal drug like Amphotericin-B and novel drugs like Rezafungin, encochleated Amphotericin B, Orolofim, and SCY-078 which have been explored in last few years. This review provides an overview of mucormycosis including its epidemiology, pathophysiology, risk factors, its clinical forms, and therapeutic approaches for disease management like antifungal therapy, surgical debridement, and iron chelators. The published patents and ongoing clinical trials related to mucormycosis have also been mentioned in this review.

Adverse Effects Associated With Currently Commonly Used Antifungal Agents: A Network Meta-Analysis and Systematic Review

Background: Invasive fungal infections (IFI) is an important contributing factor in morbidity and mortality of immunocompromised and critically ill patients. Although the therapeutic effects of these drugs on IFI have been well documented, the long-term use of antifungal agents has raised concerns about drug tolerability and treatment-related toxicity risks.

Methods: We searched articles published before June 30, 2020 in four electronic databases: Web of Science, Cochrane Library, embase and PubMed.

Results: 66 trials were determined to meet our inclusion criteria, providing data on 18,230 participants. We sorted out 23 AEs by system organ classes and six laboratory AEs, 13 of these were used to construct 13 network meta-analyses. Compared with LAmB, anidulafungin, caspofungin, micafungin, fluconazole, and posaconazole had a significantly low incidence of discontinuation of therapy due to AEs (OR = 0.24 (0.09,0.65), 0.24 (0.13,0.43), 0.32 (0.19,0.52), 0.38 (0.23,0.62) and 0.35 (0.17,0.69), respectively).

Conclusion: We found that echinocandins are the most tolerated antifungal agents with high safety. The AEs of triazole drugs are mainly concentrated on the increase in liver enzymes, nervous system disorders, especially visual disorders, gastrointestinal disorders, and cardiac diseases. LAmB is the least tolerated and has the most abundant AEs.

Isavuconazole and Liposomal Amphotericin B as Successful Combination Therapy of Refractory Invasive Candidiasis in a Liver Transplant Recipient: A Case Report and Literature Review

Invasive fungal infections in liver transplant recipients are associated with elevated morbidity and mortality and pose a challenge to the treating physicians. Despite of lacking clinical data, the use of antifungal combination therapy is often considered to improve response rates in an immunocompromised patient population. We herein report a case of refractory invasive candidiasis in a liver transplant recipient treated successfully with a combination of isavuconazole und high-dose liposomal amphotericin B. The antimycotic combination treatment was able to clear a bloodstream infection with C. glabrata and led to regression of bilomas among tolerable side effects. The use of the above-mentioned antifungal combination therapy in a liver transplant recipient has not been reported previously. This case highlights the efficacy and safety of antifungal combination therapy in immunocompromised patients with refractory invasive candidiasis.

COVID-19 Associated Mucormycosis: A Systematic Review from Diagnostic Challenges to Management

The coronavirus disease 2019 (COVID-19) outbreak has caused significant destruction, claiming over three million lives worldwide. Post SARS-COV-2 invasion, immunosuppression with hyperglycemia and elevated ferritin levels along with steroidal treatment creates a perfect storm for opportunistic infections. There is increasing evidence of mucormycosis co-infection in COVID-19 patients, during or post-treatment. A worse prognosis, a late diagnosis, and limited guidelines of screening and management of COVID-19 associated mucormycosis have made healthcare professionals fear an epidemic alongside a pandemic. This review geographically reports cases of COVID-19 associated mucormycosis (CAM), evaluates characteristics, clinical manifestations, and outcomes of mucormycosis in COVID-19 active or recovered patients. It further describes preventive strategies and recommendations for optimal management therapy that can be adopted worldwide to curtail an impending threat to the healthcare system.

NOD: a web server to predict New use of Old Drugs to facilitate drug repurposing

Computational methods accelerate the drug repurposing pipelines that are a quicker and cost-effective alternative to discovering new molecules. However, there is a paucity of web servers to conduct fast, focussed, and customized investigations for identifying new uses of old drugs. We present the NOD web server, which has the mentioned characteristics. NOD uses a sensitive sequence-guided approach to identify close and distant homologs of a protein of interest. NOD then exploits this evolutionary information to suggest potential compounds from the DrugBank database that can be repurposed against the input protein. NOD also allows expansion of the chemical space of the potential candidates through similarity searches. We have validated the performance of NOD against available experimental and/or clinical reports. In 65.6% of the investigated cases in a control study, NOD is able to identify drugs more effectively than the searches made in DrugBank. NOD is freely-available at http://pauling.mbu.iisc.ac.in/NOD/NOD/ .

Therapeutic Drug Monitoring of Isavuconazole: Serum Concentration Variability and Success Rates for Reaching Target in Comparison with Voriconazole

Isavuconazole (ISZ) is used in the treatment of aspergillosis and mucormycosis. The purpose of this study was to evaluate the therapeutic drug monitoring (TDM) of ISZ samples from a clinical setting performed at Statens Serum Institut. Materials/methods: Isavuconazole serum concentrations were determined by fluorescent detection on a UHPLC. Serum-ISZ (s-ISZ) results were included and compared to those of serum-voriconazole (s-VRZ) in a 33 month period from March 2017. Clinical data were obtained for patients receiving ISZ. The therapeutic range was initially 2-10 mg/L, but was adjusted to 2-5 mg/L during the study period except for selected patients with Mucorales infections who received off-label doses of ISZ. Results: A total of 273 s-ISZ and 1242 s-VRZ measurements from 35 and 283 patients, respectively, were included. Seventeen patients had received both ISZ and VRZ with TDM within the study period. The median s-ISZ was 4.3 mg/L (0.5-15.4 mg/L) with 83% of measurements within the therapeutic index. The median s-VRZ was 2.6 mg/L (0.2-21.9 mg/L) with 67% of measurements within the therapeutic index. The median intra-/interindividual coefficient of variation (CV) was 43.4%/54.8% for ISZ compared to 53.2%/83.3% for VRZ. For patients receiving ISZ, the adverse events were mostly gastroenteric and few drug-drug interactions were observed. Furthermore, immediate change from ISZ to VRZ treatment seemed to lead to prolonged metabolism of ISZ with detection up to 35 days after discontinuation. Conclusions: The majority of patients achieved s-ISZ levels well within the therapeutic range with less intra/interindividual CV than patients receiving VRZ.

Invasive aspergillosis in solid organ transplant patients: diagnosis, prophylaxis, treatment, and assessment of response

BACKGROUND

Invasive aspergillosis (IA) is a rare complication in solid organ transplant (SOT) recipients. Although IA has significant implications on graft and patient survival, data on diagnosis and management of this infection in SOT recipients are still limited.

METHODS

Discussion of current practices and limitations in the diagnosis, prophylaxis, and treatment of IA and proposal of means of assessing treatment response in SOT recipients.

RESULTS

Liver, lung, heart or kidney transplant recipients have common as well as different risk factors to the development of IA, thus each category needs a separate evaluation. Diagnosis of IA in SOT recipients requires a high degree of awareness, because established diagnostic tools may not provide the same sensitivity and specificity observed in the neutropenic population. IA treatment relies primarily on mold-active triazoles, but potential interactions with immunosuppressants and other concomitant therapies need special attention.

CONCLUSIONS

Criteria to assess response have not been sufficiently evaluated in the SOT population and CT lesion dynamics, and serologic markers may be influenced by the underlying disease and type and severity of immunosuppression. There is a need for well-orchestrated efforts to study IA diagnosis and management in SOT recipients and to develop comprehensive guidelines for this population.

Cooperative Effects of an Antifungal Moiety and DMSO on Pore Formation over Lipid Membranes Revealed by Free Energy Calculations

Itraconazole is a triazole drug widely used in the treatment of fungal infections, and it is in clinical trials for treatment of several cancers. However, the drug suffers from poor solubility, while experiments have shown that itraconazole delivery in liposome nanocarriers improves both circulation half-life and tissue distribution. The drug release mechanism from the nanocarrier is still unknown, and it depends on several factors including membrane stability against defect formation. In this work, we used molecular dynamics simulations and potential of mean force (PMF) calculations to quantify the influence of itraconazole on pore formation over lipid membranes, and we compared the effect by itraconazole with a pore-stabilizing effect by the organic solvent dimethyl sulfoxide (DMSO). According to the PMFs, both itraconazole and DMSO greatly reduce the free energy of pore formation, by up to ∼20 kJ mol^-1. However, whereas large concentrations of itraconazole of 8 mol % (relative to lipid) were required, only small concentrations of a few mole % DMSO (relative to water) were sufficient to stabilize pores. In addition, itraconazole and DMSO facilitate pore formation by different mechanisms. Whereas itraconazole predominantly aids the formation of a partial defect with a locally thinned membrane, DMSO mainly stabilizes a transmembrane water needle by shielding it from the hydrophobic core. Notably, the two distinct mechanisms act cooperatively upon adding both itraconazole and DMSO to the membrane, as revealed by an additional reduction of the pore free energy. Overall, our simulations reveal molecular mechanisms and free energies of membrane pore formation by small molecules. We suggest that the stabilization of a locally thinned membrane as well as the shielding of a transmembrane water needle from the hydrophobic membrane core may be a general mechanism by which amphiphilic molecules facilitate pore formation over lipid membranes at sufficient concentrations.

In Vitro Activities of Ravuconazole and Isavuconazole against Dematiaceous Fungi

The in vitro activities of 11 antifungals against 84 dematiaceous fungi were tested. For most tested fungal species, the MIC values of ravuconazole and isavuconazole were lower than those obtained with itraconazole, voriconazole, and posaconazole. Ravuconazole and isavuconazole appear to be more efficient against most dematiaceous fungal infections than the other triazoles. However, some pigmented fungi, such as Bipolaris spicifera and Veronaea botryosa, remain more susceptible to other triazoles or to echinocandins.

Targeting a critical step in fungal hexosamine biosynthesis

Aspergillus fumigatus is a human opportunistic fungal pathogen whose cell wall protects it from the extracellular environment including host defenses. Chitin, an essential component of the fungal cell wall, is synthesized from UDP-GlcNAc produced in the hexosamine biosynthetic pathway. As this pathway is critical for fungal cell wall integrity, the hexosamine biosynthesis enzymes represent potential targets of antifungal drugs. Here, we provide genetic and chemical evidence that glucosamine 6-phosphate N-acetyltransferase (Gna1), a key enzyme in this pathway, is an exploitable antifungal drug target. GNA1 deletion resulted in loss of fungal viability and disruption of the cell wall, phenotypes that could be rescued by exogenous GlcNAc, the product of the Gna1 enzyme. In a murine model of aspergillosis, the Δgna1 mutant strain exhibited attenuated virulence. Using a fragment-based approach, we discovered a small heterocyclic scaffold that binds proximal to the Gna1 active site and can be optimized to a selective submicromolar binder. Taken together, we have provided genetic, structural, and chemical evidence that Gna1 is an antifungal target in A. fumigatus.

Candidiasis and Mechanisms of Antifungal Resistance

Candidiasis can be present as a cutaneous, mucosal or deep-seated organ infection, which is caused by more than 20 types of Candida sp., with C. albicans being the most common. These are pathogenic yeast and are usually present in the normal microbiome. High-risk individuals are patients of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), organ transplant, and diabetes. During infection, pathogens can adhere to complement receptors and various extracellular matrix proteins in the oral and vaginal cavity. Oral and vaginal Candidiasis results from the overgrowth of Candida sp. in the hosts, causing penetration of the oral and vaginal tissues. Symptoms include white patches in the mouth, tongue, throat, and itchiness or burning of genitalia. Diagnosis involves visual examination, microscopic analysis, or culturing. These infections are treated with a variety of antifungals that target different biosynthetic pathways of the pathogen. For example, echinochandins target cell wall biosynthesis, while allylamines, azoles, and morpholines target ergosterol biosynthesis, and 5-Flucytosine (5FC) targets nucleic acid biosynthesis. Azoles are commonly used in therapeutics, however, because of its fungistatic nature, Candida sp. evolve azole resistance. Besides azoles, Candida sp. also acquire resistance to polyenes, echinochandins, and 5FC. This review discusses, in detail, the drug resistance mechanisms adapted by Candida sp.

Sternal osteomyelitis secondary to Aspergillus fumigatus after cardiothoracic surgery

Sternal Osteomyelitis from Aspergillus fumigatus in immunocompetent patients is extremely rare with limited number of cases reported so far. Here we discuss the case of a 65-year-old female with osteomyelitis of the sternum caused by Aspergillus fumigatus after undergoing coronary artery bypass graft surgery. Patient was treated with surgical debridement and prolonged antifungal therapy; however, the course was complicated due to poor adherence to antifungal therapy.

Multiresistant Fusarium Pathogens on Plants and Humans: Solutions in (from) the Antifungal Pipeline?

The fungal genus Fusarium contains numerous plant pathogens causing considerable economic losses. In addition, Fusarium species are emerging as opportunistic human pathogens causing both superficial and systemic infections. Appropriate treatment of Fusarium infections in a clinical setting of neutropenia is currently not available. ESCMID and ECMM joint guidelines, following the majority of published studies, suggest early therapy with amphotericin B and voriconazole, in conjunction with surgical debridement and reversal of immunosuppression. In this review, we elaborate on the trans-kingdom pathogenicity of Fusarium. Intrinsic resistance to several antifungal drugs and the evolution of antifungal resistance over the years are highlighted. Recent studies present novel compounds that are effective against some pathogenic fungi including Fusarium. We discuss the robust and dynamic antifungal pipeline, including results from clinical trials as well as preclinical data that might appear beneficial for patients with invasive fusariosis.

Central nervous system disorders after hematopoietic stem cell transplantation: a prospective study of the Infectious Diseases Working Party of EBMT

We performed a prospective study to evaluate the types and characteristics of central nervous system (CNS) disorders in patients after hematopoietic stem cell transplantation. The study included 163 episodes of CNS disorders of which 58 (36%) were infections. Proven or probable infections were documented in 34 patients and included fungi (n = 10, 29%), viruses (n = 12, 35%), Toxoplasma spp. (n = 9, 27%) and bacteria (n = 3, 9%). Non-infectious neurological disorders (n = 105, 64%) frequently encompassed metabolic/drug-induced abnormalities (n = 28, 27%) or cerebral vascular events (n = 22, 21%). Median onset times were later for infectious (day + 101) vs non-infectious neurological disorders (day + 50, p = 0.009). An unremarkable cranial CT scan was found in 33% of infection episodes. Absence of cerebrospinal fluid pleocytosis despite a normal or increased peripheral blood white blood cell count occurred in 26% of infections. Day-30 mortality rates were significantly higher for fungal (87%) vs non-fungal infections (40%, p < 0.001). Significantly higher mortality rates were also documented for cerebral vascular events than for other non-infectious disorders (86% vs 34%, p < 0.001). Our prospective study shows that diagnostic findings in CNS infections might differ between hematopoietic stem cell transplant recipients and immunocompetent hosts. Special awareness and timely initiation of adequate diagnostics are crucial to improve the prognosis of these patients.

Antifungal Drugs: Special Problems Treating Central Nervous System Infections

Treating fungal infections in the central nervous system (CNS) remains a challenge despite the availability of new antifungal agents. Therapy is limited by poor understanding of the kinetic properties of antifungal drugs in the CNS compounded by lack of data for many agents. In some cases, clinical response rates do not correspond to data on drug concentrations in the cerebral spinal fluid and/or brain parenchyma. In order to better characterize the use of antifungal agents in treating CNS infections, a review of the essential principles of neuroPK are reviewed. Specific data regarding antifungal drug concentrations in the cerebral spinal fluid and brain tissue are described from human data where available. Alternative dosing regimens and the role of antifungal drug concentration monitoring in treating fungal infections in the CNS are also discussed. Having a better understanding of these key concepts will help guide clinicians in determining the best treatment courses for patients with these devastating infections.

Delamanid Central Nervous System Pharmacokinetics in Tuberculous Meningitis in Rabbits and Humans

Central nervous system tuberculosis (TB) is devastating and affects vulnerable populations. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculous meningitis (TBM) specifically are nearly uniformly fatal, with little information being available to guide the treatment of these patients. Delamanid (DLM), a nitro-dihydro-imidazooxazole, is a new, well-tolerated anti-TB drug with a low MIC (1 to 12 ng/ml) against Mycobacterium tuberculosis It is used for the treatment of pulmonary MDR-TB, but pharmacokinetic (PK) data for DLM in the central nervous system (CNS) of patients with TBM are not available. In the present study, we measured DLM concentrations in the brain and cerebrospinal fluid (CSF) of six rabbits with and without experimentally induced TBM receiving single-dose DLM. We report the steady-state CSF concentrations from three patients receiving DLM as part of multidrug treatment who underwent therapeutic drug monitoring. Drug was quantified using liquid chromatography-tandem mass spectrometry. In rabbits and humans, mean concentrations in CSF (in rabbits, 1.26 ng/ml at 9 h and 0.47 ng/ml at 24 h; in humans, 48 ng/ml at 4 h) were significantly lower than those in plasma (in rabbits, 124 ng/ml at 9 h and 14.5 ng/ml at 24 h; in humans, 726 ng/ml at 4 h), but the estimated free CSF/plasma ratios were generally >1. In rabbits, DLM concentrations in the brain were 5-fold higher than those in plasma (means, 518 ng/ml at 9 h and 74.0 ng/ml at 24 h). All patients with XDR-TBM receiving DLM experienced clinical improvement and survival. Collectively, these results suggest that DLM achieves adequate concentrations in brain tissue. Despite relatively low total CSF drug levels, free drug may be sufficient and DLM may have a role in treating TBM. More studies are needed to develop a fuller understanding of its distribution over time with treatment and clinical effectiveness.

Update in Infectious Diseases 2019

The IX Course of Antimicrobials and Infectious Diseases update included a review of the main issues in clinical microbiology, epidemiology and clinical aspects for a current approach of infectious pathology. The present introduction summarizes about the most important meetings related to infectious diseases during 2018 (ECCMID, IAS, ASM and ID Week). In addition, the course provides a practical information to focus on nosocomial infection models, with immunosuppressed patients or complex multidrug-resistant pathogens. The closing lecture of this year reviewed the infection during donation process.

Considerations for Medications Commonly Utilized in the Oncology Population in the Intensive Care Unit

An increasing number of oncologic patients are presenting to the intensive care unit with complications from both their chronic disease states and cancer therapies due to improved survival rates. The management of these patients is complex due to immunosuppression (from the malignancy and/or treatment), metabolic complications, and diverse medication regimens with the potential for significant drug-drug interactions and overlapping adverse effects. This chapter will provide clinicians with an overview of non-chemotherapy medications frequently encountered in the critically ill oncologic patient, with a focus on practical considerations.

Antifungal Drugs Influence Neutrophil Effector Functions

There is a growing body of evidence for immunomodulatory side effects of antifungal agents on different immune cells, e.g., T cells. Therefore, the aim of our study was to clarify these interactions with regard to the effector functions of polymorphonuclear neutrophils (PMN). Human PMN were preincubated with fluconazole (FLC), voriconazole (VRC), posaconazole (POS), isavuconazole (ISA), caspofungin (CAS), micafungin (MFG), conventional amphotericin B (AMB), and liposomal amphotericin B (LAMB). PMN then were analyzed by flow cytometry for activation, degranulation, and phagocytosis and by dichlorofluorescein assay to detect reactive oxygen species (ROS). Additionally, interleukin-8 (IL-8) release was measured by enzyme-linked immunosorbent assay. POS led to enhanced activation, degranulation, and generation of ROS, whereas IL-8 release was reduced. In contrast, ISA-pretreated PMN showed decreased activation signaling, impaired degranulation, and lower generation of ROS. MFG caused enhanced expression of activation markers but impaired degranulation, phagocytosis, generation of ROS, and IL-8 release. CAS showed increased phagocytosis, whereas degranulation and generation of ROS were reduced. AMB led to activation of almost all effector functions besides impaired phagocytosis, whereas LAMB did not alter any effector functions. Independent from class, antifungal agents show variable influence on neutrophil effector functions in vitro Whether this is clinically relevant needs to be clarified.

A case report of disseminated histoplasmosis and concurrent cryptococcal meningitis in a patient treated with ruxolitinib

Background

Ruxolitinib is a highly potent janus kinase inhibitor that places its users at risk for various bacterial infections and viral reactivation. However new reports are also emerging that suggest greater immunosuppression and risk for fungal disease.

Case presentation

We report the case of a 51 year-old veteran from Guam, treated with ruxolitinib for polycythemia vera, who developed disseminated histoplasmosis and concurrent cryptococcal meningitis.

Conclusion

This case draws attention to the degree of immunosuppression that may be seen with this drug and the need for heightened vigilance for opportunistic infections in those treated with inhibitors of janus kinase/signal transducers and activators of transcription (JAK/STAT) such as ruxolitinib.

Prophylaxis of mould infections

Invasive fungal infection continues to be an important cause of morbidity and mortality in haematological patients. Antifungal prophylaxis in these patients has remarkably increased survival since its introduction. In recent years, new antifungals have been on the rise, being more effective and having less toxicity than previous ones. Nonetheless, the number of patients at risk of fungal infection has also been increasing due to the continuous appearance of new immunosuppressive treatments. As a result of such, we face a changing situation that requires constant updating.

In vitro activity of isavuconazole against fluconazole-resistant isolates of Histoplasma capsulatum

No clinical trials for histoplasmosis have been performed with the newer azoles, leaving itraconazole as the azole of choice. In vitro studies suggest that Histoplasma capsulatum from patients that relapse on fluconazole has higher minimum inhibitory concentrations (MICs) to fluconazole and voriconazole but not itraconazole and posaconazole. The newest azole, isavuconazole, shares structural similarity to voriconazole, but to date nobody has explored emergence of resistance. In vitro susceptibilities to isavucoanzole and fluconazole were performed on previously obtained isolates from the patients who relapsed on fluconazole therapy. Susceptibilities were determined by NCCLS method M27A developed for yeasts, as modified for H. capsulatum. The change in the MIC from the primary to the relapse isolate was tested using Wilcoxon Rank-Sum for paired data. Among the primary isolates, the median MICs were 1.0 (range 0.25 to 4.0) μg/ml for fluconazole and ≤0.007 (range ≤0.007 to 0.015) μg/ml for isavuconazole. In the group of relapsed isolates, the median MICs rose to 8.0 (range 0.25 to 64.0) μg/ml for fluconazole and remained unchanged at ≤0.007 (range ≤0.007 to 0.015) μg/ml for isavuconazole (P < .001). Only one isolate exhibited a nonsignificant increase in MIC to isavuconazole. Histoplasma isolates from patients who relapsed on fluconazole did not have an elevation in MICs to isavuconazole. This differs from the results previously seen with voriconazole and suggests that despite a closer structural similarity to voriconazole than itraconazole and posaconazole, isavuconazole has a higher barrier to resistance and may be effective as therapy for histoplasmosis.

A 53-Year-Old Male with Relapsed Diffuse Large B-Cell Lymphoma on Chemotherapy with a New Leg Lesion

Patients with underlying malignancy who develop new skin findings while acutely ill often require skin biopsy for histologic evaluation and/or culture to reach a diagnosis. Here, we present the case of a 53-year-old male with relapsed diffuse large B-cell lymphoma on chemotherapy who developed new skin lesions on the leg. On exam, there were 2 nickel-sized, erythematous to violaceous round plaques with central necrotic cores on the right lower leg with relatively nonspecific clinical features for which the initial differential diagnosis was broad. Consensus on a diagnosis was reached upon histologic evaluation of his skin biopsy in the context of his clinical setting. This diagnosis led to a change in treatment plan, with subsequent clinical improvement.

Cutaneous mucormycosis

Cutaneous mucormycosis is an emerging fungal infection caused by opportunistic fungi of the phylum Glomeromycota. It is frequent in poorly controlled diabetic patients and individuals with immunosuppression. It is usually acquired by direct inoculation through trauma. The clinical presentation is nonspecific, but an indurated plaque that rapidly evolves to necrosis is a common finding. Diagnosis should be confirmed by demonstration of the etiological agent and new molecular diagnostic tools have recently been described. It is an invasive life-threatening disease and in order to improve survival, a prompt diagnosis and multidisciplinary management should be provided. The treatment of choice is amphotericin B, but new azoles, such as posaconazole and isavuconazole, must be considered.

QT Interval Shortening With Isavuconazole: In Vitro and In Vivo Effects on Cardiac Repolarization

The effects of isavuconazole (active moiety of isavuconazonium sulfate) on cardiac ion channels in vitro and cardiac repolarization clinically were assessed in a phase I, randomized, double-blind study in healthy individuals who received isavuconazole (after 2-day loading dose), at therapeutic or supratherapeutic doses daily for 11 days, moxifloxacin (400 mg q.d.), or placebo. A post-hoc analysis of the phase III SECURE trial assessed effects on cardiac safety. L-type Ca2+ channels were most sensitive to inhibition by isavuconazole. The 50% inhibitory concentrations for ion channels were higher than maximum serum concentrations of nonprotein-bound isavuconazole in vivo. In the phase I study (n = 161), isavuconazole shortened the QT interval in a dose- and plasma concentration-related manner. There were no serious treatment-emergent adverse events; palpitations and tachycardia were observed in placebo and supratherapeutic isavuconazole groups; no cardiac safety signals were detected in the SECURE study (n = 257). Isavuconazole was associated with a shortened cardiac QT interval.

Pseudomembranous aspergillar tracheobronchitis in a non-neutropenic critically ill patient in the intensive care unit

Invasive aspergillosis is an important cause of morbidity and mortality among immunocompromised patients. Prolonged neutropenia is the most common risk factor. It has rarely been reported to occur in non-neutropenic critically ill patients in the intensive care unit setting. Mortality rate in this group has been reported to be as high as 92%. We report a case of tracheobronchial aspergillosis in a non-neutropenic critically ill patient to highlight the fact that critically ill patients admitted in the intensive care unit can develop opportunistic infections such as invasive aspergillosis even in the absence of classic risk factors and prior history of immunosuppression. Early diagnosis and prompt initiation of antifungal therapy may improve the outcome and decrease mortality rate.

Isavuconazole for the treatment of invasive aspergillosis and mucormycosis: current evidence, safety, efficacy, and clinical recommendations

The majority of invasive mold infections diagnosed in immunocompromised cancer patients include invasive aspergillosis (IA) and mucormycosis. Despite timely and effective therapy, mortality remains considerable. Antifungal agents currently available for the management of these serious infections include triazoles, polyenes, and echinocandins. Until recently, posaconazole has been the only triazole with a broad spectrum of anti-mold activity against both Aspergillus sp. and mucorales. Other clinically available triazoles voriconazole and itraconazole, with poor activity against mucorales, have significant drug interactions in addition to a side effect profile inherent for all triazoles. Polyenes including lipid formulations pose a problem with infusion-related side effects, electrolyte imbalance, and nephrotoxicity. Echinocandins are ineffective against mucorales and are approved as salvage therapy for refractory IA. Given that all available antifungal agents have limitations, there has been an unmet need for a broad-spectrum anti-mold agent with a favorable profile. Following phase III clinical trials that started in 2006, isavuconazole (ISZ) seems to fit this profile. It is the first novel triazole agent recently approved by the United States Food and Drug Administration (FDA) for the treatment of both IA and mucormycosis. This review provides a brief overview of the salient features of ISZ, its favorable profile with regard to spectrum of antifungal activity, pharmacokinetic and pharmacodynamic parameters, drug interactions and tolerability, clinical efficacy, and side effects.

Population Pharmacokinetics of Isavuconazole from Phase 1 and Phase 3 (SECURE) Trials in Adults and Target Attainment in Patients with Invasive Infections Due to Aspergillus and Other Filamentous Fungi

Isavuconazole, the active moiety of the water-soluble prodrug isavuconazonium sulfate, is a triazole antifungal agent used for the treatment of invasive fungal infections. The objective of this analysis was to develop a population pharmacokinetic (PPK) model to identify covariates that affect isavuconazole pharmacokinetics and to determine the probability of target attainment (PTA) for invasive aspergillosis patients. Data from nine phase 1 studies and one phase 3 clinical trial (SECURE) were pooled to develop the PPK model (NONMEM, version 7.2). Stepwise covariate modeling was performed in Perl-speaks-NONMEM, version 3.7.6. The area under the curve (AUC) at steady state was calculated for 5,000 patients by using Monte Carlo simulations. The PTA using the estimated pharmacodynamic (PD) target value (total AUC/MIC ratio) estimated from in vivo PD studies of invasive aspergillosis over a range of MIC values was calculated using simulated patient AUC values. A two-compartment model with a Weibull absorption function and a first-order elimination process adequately described plasma isavuconazole concentrations. The mean estimate for isavuconazole clearance was 2.360 liters/h (percent coefficient of variation [%CV], 34%), and the mean AUC from 0 to 24 h (AUC0-24) was ∼100 mg·h/liter. Clearance was approximately 36% lower in Asians than in Caucasians. The PTA calculated over a range of MIC values by use of the nonneutropenic murine efficacy index corresponding to 90% survival indicated that adequate isavuconazole exposures were achieved in >90% of simulated patients to treat infections with MICs up to and including 1 mg/liter according to European Committee on Antimicrobial Susceptibility Testing methodology and in >90% of simulated patients for infections with MICs up to and including 0.5 mg/liter according to Clinical and Laboratory Standards Institute methodology. The highest MIC result for PTA was the same for Caucasian and Asian patients.

Role of isavuconazole in the treatment of invasive fungal infections

Despite recent advances in both diagnosis and prevention, the incidence of invasive fungal infections continues to rise. Available antifungal agents to treat invasive fungal infections include polyenes, triazoles, and echinocandins. Unfortunately, individual agents within each class may be limited by spectrum of activity, resistance, lack of oral formulations, significant adverse event profiles, substantial drug–drug interactions, and/or variable pharmacokinetic profiles. Isavuconazole, a second-generation triazole, was approved by the US Food and Drug Administration in March 2015 and the European Medicines Agency in July 2015 for the treatment of adults with invasive aspergillosis (IA) or mucormycosis. Similar to amphotericin B and posaconazole, isavuconazole exhibits a broad spectrum of in vitro activity against yeasts, dimorphic fungi, and molds. Isavuconazole is available in both oral and intravenous formulations, exhibits a favorable safety profile (notably the absence of QTc prolongation), and reduced drug–drug interactions (relative to voriconazole). Phase 3 studies have evaluated the efficacy of isavuconazole in the management of IA, mucormycosis, and invasive candidiasis. Based on the results of these studies, isavuconazole appears to be a viable treatment option for patients with IA as well as those patients with mucormycosis who are not able to tolerate or fail amphotericin B or posaconazole therapy. In contrast, evidence of isavuconazole for invasive candidiasis (relative to comparator agents such as echinocandins) is not as robust. Therefore, isavuconazole use for invasive candidiasis may initially be reserved as a step-down oral option in those patients who cannot receive other azoles due to tolerability or spectrum of activity limitations. Post-marketing surveillance of isavuconazole will be important to better understand the safety and efficacy of this agent, as well as to better define the need for isavuconazole serum concentration monitoring.

Hot topics in antifungal susceptibility testing: A new drug, a bad bug, sweeping caspofungin testing under the rug, and solving the ECV shrug

There are several new hot topics in antifungals and antifungal susceptibility testing. In this review, four topics of general interest to the clinical microbiology community are discussed. The first topic is the introduction of isavuconazole, a new triazole approved for clinical use in the US. The second is triazole resistance in Aspergillus fumigatus isolates. A specific set of mutations are being found with greater frequency in isolates globally, including the US. The third topic of interest is a word of caution about antifungal susceptibility testing for caspofungin in Candida isolates; some laboratories have reported susceptible isolates with high MIC values that would be interpreted as resistant. The final topic is an introduction to epidemiological cutoff values and their use in the clinical mycology laboratory.

Isavuconazole in the treatment of invasive aspergillosis and mucormycosis infections

We have a limited arsenal with which to treat invasive fungal infections caused by Aspergillus and Mucorales. The morbidity and mortality for both pathogens remains high. A triazole antifungal, isavuconazole, was recently granted approval by the US Food and Drug Administration and the European Medicines Agency for the treatment of invasive aspergillosis and mucormycosis. A randomized double-blind comparison trial for the treatment of invasive aspergillosis found isavuconazole noninferior to voriconazole. A separate, open-label study evaluating the efficacy of isavuconazole in the treatment of mucormycosis found comparable response rates to amphotericin B and posaconazole treated historical controls. The prodrug isavuconazonium sulfate is commercially available in both an oral and intravenous formulation and is generally well tolerated. Isavuconazole’s broad spectrum of activity, limited side effect profile, and favorable pharmacokinetics will likely solidify its place in therapy.

Synthesis and Bioactivities of Kanamycin B-Derived Cationic Amphiphiles

Cationic amphiphiles derived from aminoglycosides (AGs) have been shown to exhibit enhanced antimicrobial activity. Through the attachment of hydrophobic residues such as linear alkyl chains on the AG backbone, interesting antibacterial and antifungal agents with a novel mechanism of action have been developed. Herein, we report the design and synthesis of seven kanamycin B (KANB) derivatives. Their antibacterial and antifungal activities, along with resistance/enzymatic, hemolytic, and cytotoxicity assays were also studied. Two of these compounds, with a C12 and C14 aliphatic chain attached at the 6″-position of KANB through a thioether linkage, exhibited good antibacterial and antifungal activity, were poorer substrates than KANB for several AG-modifying enzymes, and could delay the development of resistance in bacteria and fungi. Also, they were both relatively less hemolytic than the known membrane targeting antibiotic gramicidin and the known antifungal agent amphotericin B and were not toxic at their antifungal MIC values. Their oxidation to sulfones was also demonstrated to have no effect on their activities. Moreover, they both acted synergistically with posaconazole, an azole currently used in the treatment of human fungal infections.

A combination approach to treating fungal infections

Azoles are antifungal drugs used to treat fungal infections such as candidiasis in humans. Their extensive use has led to the emergence of drug resistance, complicating antifungal therapy for yeast infections in critically ill patients. Combination therapy has become popular in clinical practice as a potential strategy to fight resistant fungal isolates. Recently, amphiphilic tobramycin analogues, C₁₂ and C₁₄, were shown to display antifungal activities. Herein, the antifungal synergy of C₁₂ and C₁₄ with four azoles, fluconazole (FLC), itraconazole (ITC), posaconazole (POS), and voriconazole (VOR), was examined against seven Candida albicans strains. All tested strains were synergistically inhibited by C₁₂ when combined with azoles, with the exception of C. albicans 64124 and MYA-2876 by FLC and VOR. Likewise, when combined with POS and ITC, C₁₄ exhibited synergistic growth inhibition of all C. albicans strains, except C. albicans MYA-2876 by ITC. The combinations of FLC-C₁₄ and VOR-C₁₄ showed synergistic antifungal effect against three C. albicans and four C. albicans strains, respectively. Finally, synergism between C₁₂/C₁₄ and POS were confirmed by time-kill and disk diffusion assays. These results suggest the possibility of combining C₁₂ or C₁₄ with azoles to treat invasive fungal infections at lower administration doses or with a higher efficiency.

Role of New Antifungal Agents in the Treatment of Invasive Fungal Infections in Transplant Recipients: Isavuconazole and New Posaconazole Formulations

Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients. Transplant patients are at risk for such invasive fungal infections. The most common invasive fungal infections are invasive candidiasis in the SOT and invasive aspergillosis in the HSCT. In this article, we will discuss the epidemiology of invasive fungal infections in the transplant recipients and susceptibility patterns of the fungi associated with these infections. Additionally, the pharmacology and clinical efficacy of the new antifungal, isavuconazole, and the new posaconazole formulations will be reviewed. Isavuconazole is a new extended-spectrum triazole that was recently approved for the treatment of invasive aspergillosis and mucormycosis. Advantages of this triazole include the availability of a water-soluble intravenous formulation, excellent bioavailability of the oral formulation, and predictable pharmacokinetics in adults. Posaconazole, a broad-spectrum triazole antifungal agent, is approved for the prevention of invasive aspergillosis and candidiasis in addition to the treatment of oropharyngeal candidiasis. Posaconazole oral suspension solution has shown some limitations in the setting of fasting state absorption, elevated gastrointestinal pH, and increased motility. The newly approved delayed-release oral tablet and intravenous solution formulations provide additional treatment options by reducing interpatient variability and providing flexibility in these set of critically ill patients. This review will detail these most recent studies.

Advances in the treatment of invasive neonatal candidiasis

INTRODUCTION

Invasive candidiasis is responsible for ∼ 10% of nosocomial sepsis in very-low-birth-weight infants and is associated with substantial morbidity and mortality. Over the last two decades, the antifungal armamentarium against Candida spp. has increased; however, efficacy and safety studies in this population are lacking.

AREAS COVERED

We reviewed the medical literature and extracted information on clinical and observational studies evaluating the use of antifungal agents in neonates with invasive candidiasis.

EXPERT OPINION

Efficacy and safety data for antifungals in neonates are lacking, and the majority of studies conducted to date have concentrated on pharmacokinetic/pharmacodynamic evaluations. Unlike other anti-infective agents, efficacy data in the setting of neonatal candidiasis cannot be extrapolated from adult studies due to differences in the pathophysiology of the disease in this population relative to older children and adults. Data for amphotericin B deoxycholate, fluconazole, and micafungin suggest that these are the current agents of choice for this disease in neonates until data for newer antifungal agents become available. For prophylaxis, data from fluconazole randomized controlled trials will be submitted to the regulatory agencies for labeling. Ultimately, the field of therapeutics for neonatal candidiasis will require multidisciplinary collaboration given the numerous challenges associated with conducting clinical trials in neonates.

Pharmacodynamics of isavuconazole in an Aspergillus fumigatus mouse infection model

Azole resistance is an emerging problem in Aspergillus fumigatus which translates into treatment failure. Alternative treatments with new azoles may improve therapeutic outcome in invasive aspergillosis (IA) even for strains with decreased susceptibility to current azoles. The in vivo efficacy of 0.25, 1, 4, 16, 64, 128, 256, and 512 mg/kg of body weight/day prodrug isavuconazonium sulfate (BAL8557) (isavuconazole [ISA]-equivalent doses of 0.12, 0.48, 1.92, 7.68, 30.7, 61.4, 122.9, and 245.8 mg/kg/day, respectively) administered by oral gavage was assessed in an immunocompetent murine model of IA against four clinical A. fumigatus isolates: a wild-type isolate (ISA MICEUCAST, 0.5 mg/liter) and three azole-resistant isolates harboring substitutions in the cyp51A gene: G54W (ISA MIC(EUCAST), 0.5 mg/liter), M220I (ISA MIC(EUCAST), 4 mg/liter), and TR34/L98H (ISA MIC(EUCAST), 8 mg/liter). The maximum effect (100% survival) was reached at a prodrug isavuconazonium sulfate dose of 64 mg/kg for the wild-type isolate, 128 mg/kg for the G54W mutant, and 256 mg/kg two times per day (q12) for the M220I mutant. A maximum response was not achieved with the TR34/L98H isolates with the highest dose of prodrug isavuconazonium sulfate (256 mg/kg q12). For a survival rate of 50%, the effective AUC(0-24)/MIC(EUCAST) ratio for ISA total drug was 24.73 (95% confidence interval, 22.50 to 27.18). The efficacy of isavuconazole depended on both the drug exposure and the isavuconazole MIC of the isolates. The quantitative relationship between exposure and effect (AUC(0-24)/MIC) can be used to optimize the treatment of human infections by A. fumigatus, including strains with decreased susceptibility.

Treatment principles for the management of mold infections

Survival rates among immunocompromised patients with invasive mold infections have markedly improved over the last decade with earlier diagnosis and new antifungal treatment options. Yet, increasing antifungal resistance, breakthrough infections with intrinsically resistant fungi, and potentially life-threatening adverse effects and drug interactions are becoming more problematic, especially with prolonged therapy. Evidence-based recommendations for treating invasive aspergillosis and mucormycosis provide excellent guidance on the initial workup and treatment of these molds, but they cannot address all of the key management issues. Herein, we discuss 10 general treatment principles in the management of invasive mold disease in immunocompromised patients and discuss how these principles can be integrated to develop an effective, individualized treatment plan.