Deferasirox, an iron-chelating agent, as salvage therapy for rhinocerebral mucormycosis

Comprehensive Review on the Virulence Factors and Therapeutic Strategies with the Aid of Artificial Intelligence against Mucormycosis

Mucormycosis, a rare but deadly fungal infection, was an epidemic during the COVID-19 pandemic. The rise in cases (COVID-19-associated mucormycosis, CAM) is attributed to excessive steroid and antibiotic use, poor hospital hygiene, and crowded settings. Major contributing factors include diabetes and weakened immune systems. The main manifesting forms of CAM─cutaneous, pulmonary, and the deadliest, rhinocerebral─and disseminated infections elevated mortality rates to 85%. Recent focus lies on small-molecule inhibitors due to their advantages over standard treatments like surgery and liposomal amphotericin B (which carry several long-term adverse effects), offering potential central nervous system penetration, diverse targets, and simpler dosing owing to their small size, rendering the ability to traverse the blood-brain barrier via passive diffusion facilitated by the phospholipid membrane. Adaptation and versatility in mucormycosis are facilitated by a multitude of virulence factors, enabling the pathogen to dynamically respond to various environmental stressors. A comprehensive understanding of these virulence mechanisms is imperative for devising effective therapeutic interventions against this highly opportunistic pathogen that thrives in immunocompromised individuals through its angio-invasive nature. Hence, this Review delineates the principal virulence factors of mucormycosis, the mechanisms it employs to persist in challenging host environments, and the current progress in developing small-molecule inhibitors against them.

Role of Amphotericin B in the Treatment of Mucormycosis

BACKGROUND

Regardless of the most recent inclusion of mold-active agents (isavuconazole and posaconazole) to antifungal agents against mucormycosis, in conjunction with amphotericin B (AMB) items, numerous uncertainties still exist regarding the treatment of this rare infection. The order Mucorales contains a variety of fungi that cause the serious but uncommon fungal illness known as mucormycosis. The moulds are prevalent in nature and typically do not pose significant risks to people. Immunocompromised people are affected by it.

OBJECTIVE

This article's primary goal is to highlight the integral role that AMB plays in this condition.

METHODS

Like sinusitis (including pansinusitis, rhino-orbital, or rhino-cerebral sinusitis) is one of the many signs and symptoms of mucormycosis. The National Center for Biotechnology Information (NCBI) produces a variety of online information resources for review articles on the topic-based mucormycosis, AMB, diagnosis of mucormycosis and the PubMed® database of citations and abstracts published in life science journals. These resources can be accessed through the NCBI home page at https://www.ncbi.nlm.nih.gov.

RESULTS

The article provides a summary of the pharmacological attributes of the various AMB compositions accessible for systemic use.

CONCLUSION

The article demonstrates the traits of the drug associated with its chemical, pharmacokinetics, stability, and other features, and illustrates their most useful characteristics for clinical application.

An extensive review on antifungal approaches in the treatment of mucormycosis

During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B (1) and isavuconazole (2) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole (3) and deferasirox (4) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 (5) and APX001A (6), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis.

Theoretical and experimental studies on mechanochromic triphenylamine based fluorescent "ON-OFF-ON" sensor for sequential detection of Fe3+ and deferasirox

A novel triphenylamine (TPA) based sensor TTU was rationally designed and synthesized that exhibited reversible mechanochromic and aggregation induced emission enhancement (AIEE) properties. The AIEE active sensor was employed for fluorometric detection of Fe³⁺ in aqueous medium, with distinguished selectivity. The sensor showed a highly selective quenching response towards Fe³⁺ that is ascribed to complex formation with paramagnetic Fe³⁺. Subsequently, TTU-Fe³⁺ complex acted as a fluorescence sensor for the detection of deferasirox (DFX). The subsequent addition of DFX to TTU-Fe³⁺ complex led to the recovery of fluorescence emission intensity of sensor TTU that was attributed to the displacement of Fe³⁺ by DFX and release of sensor TTU. The proposed sensing mechanisms for Fe³⁺ and DFX was confirmed through ¹H NMR titration experiment and DFT calculations. Frontier molecular orbitals (FMO), density of states (DOS), natural bond orbital (NBO), non-covalent interaction (NCI) and electron density difference (EDD) analysis were performed using DFT calculations to support the experimental results. Moreover, sensor TTU displayed colorimetric detection of Fe³⁺. Further, the sensor was employed for the detection of Fe³⁺ and DFX in real water samples. Finally, logic gate was fabricated by using sequential detection strategy.

Mucormycosis: risk factors, diagnosis, treatments, and challenges during COVID-19 pandemic

Mucormycosis is a deadly opportunistic disease caused by a group of fungus named mucormycetes. Fungal spores are normally present in the environment and the immune system of the body prevents them from causing disease in a healthy immunocompetent individual. But when the defense mechanism of the body is compromised such as in the patients of diabetes mellites, neustropenia, organ transplantation recipients, and other immune-compromised states, these fungal spores invade our defense mechanism easily causing a severe systemic infection with approximately 45-80% of case fatality. In the present scenario, during the COVID-19 pandemic, patients are on immunosuppressive drugs, glucocorticoids, thus are at high risk of mucormycosis. Patients with diabetes mellitus are further getting a high chance of infection. Usually, the spores gain entry through our respiratory tract affecting the lungs and paranasal sinuses. Besides, they can also enter through damage into the skin or through the gastrointestinal route. This review article presents the current statistics, the causes of this infection in the human body, and its diagnosis with available recent therapies through recent databases collected from several clinics and agencies. The diagnosis and identification of the infection were made possible through various latest medical techniques such as computed tomography scans, direct microscopic observations, MALDI-TOF mass spectrometry, serology, molecular assay, and histopathology. Mucormycosis is so uncommon, no randomized controlled treatment studies have been conducted. The newer triazoles, posaconazole (POSA) and isavuconazole (ISAV) (the active component of the prodrug isavuconazonium sulfate) may be beneficial in patients who are refractory to or intolerant of Liposomal Amphotericin B. but due to lack of early diagnosis and aggressive surgical debridement or excision, the mortality rate remains high. In the course of COVID-19 treatments, there must be more vigilance and alertness are required from clinicians to evaluate these invasive fungal infections.

Mucormycosis Amid COVID-19 Crisis: Pathogenesis, Diagnosis, and Novel Treatment Strategies to Combat the Spread

The havoc unleashed by COVID-19 pandemic has paved way for secondary ominous fungal infections like Mucormycosis. It is caused by a class of opportunistic pathogens from the order Mucorales. Fatality rates due to this contagious infection are extremely high. Numerous clinical manifestations result in damage to multiple organs subject to the patient's underlying condition. Lack of a proper detection method and reliable treatment has made the management of this infection troublesome. Several reports studying the behavior pattern of Mucorales inside the host by modulation of its defense mechanisms have helped in understanding the pathogenesis of this angio-invasive infection. Many recent advances in diagnosis and treatment of this fungal infection have not been much beneficial. Therefore, there is a need to foster more viable strategies. This article summarizes current and imminent approaches that could aid effective management of these secondary infections in these times of global pandemic. It is foreseen that the development of newer antifungal drugs, antimicrobial peptides, and nanotechnology-based approaches for drug delivery would help combat this infection and curb its spread.

Mucormycosis in Indian COVID-19 Patients: Insight into Its Patho-Genesis, Clinical Manifestation, and Management Strategies

Mucormycosis in patients who have COVID-19 or who are otherwise immunocompromised has become a global problem, causing significant morbidity and mortality. Infection is debilitating and fatal, leading to loss of organs and emotional trauma. Radiographic manifestations are not specific, but diagnosis can be made through microscopic examination of materials collected from necrotic lesions. Treatment requires multidisciplinary expertise, as the fungus enters through the eyes and nose and may even reach the brain. Use of the many antifungal drugs available is limited by considerations of resistance and toxicity, but nanoparticles can overcome such limitations by reducing toxicity and increasing bioavailability. The lipid formulation of amphotericin-B (liposomal Am-B) is the first-line treatment for mucormycosis in COVID-19 patients, but its high cost and low availability have prompted a shift toward surgery, so that surgical debridement to remove all necrotic lesions remains the hallmark of effective treatment of mucormycosis in COVID-19. This review highlights the pathogenesis, clinical manifestation, and management of mucormycosis in patients who have COVID-19.

Mucormycosis

Mucormycosis is a rare but aggressive fungal disease that mainly affects patients with poorly controlled diabetes mellitus and those who are severely immunocompromised, including patients with hematological malignancies and solid organ transplant recipients. Early recognition of infection is critical for treatment success, followed by prompt initiation of antifungal therapy with lipid formulation amphotericin B. Posaconazole and isavuconazole should be used for stepdown and salvage therapy. Surgical debridement is key for tissue diagnosis and treatment and should be pursued urgently whenever possible. In addition to surgery and antifungal therapy, reverting the underlying risk factor for infection is important for treatment response.

Iron in infection and immunity

Iron is an essential micronutrient for virtually all living cells. In infectious diseases, both invading pathogens and mammalian cells including those of the immune system require iron to sustain their function, metabolism and proliferation. On the one hand, microbial iron uptake is linked to the virulence of most human pathogens. On the other hand, the sequestration of iron from bacteria and other microorganisms is an efficient strategy of host defense in line with the principles of 'nutritional immunity'. In an acute infection, host-driven iron withdrawal inhibits the growth of pathogens. Chronic immune activation due to persistent infection, autoimmune disease or malignancy however, sequesters iron not only from infectious agents, autoreactive lymphocytes and neoplastic cells but also from erythroid progenitors. This is one of the key mechanisms which collectively result in the anemia of chronic inflammation. In this review, we highlight the most important interconnections between iron metabolism and immunity, focusing on host defense against relevant infections and on the clinical consequences of anemia of inflammation.

Iron Pathways and Iron Chelation Approaches in Viral, Microbial, and Fungal Infections

Iron is an essential element required to support the health of organisms. This element is critical for regulating the activities of cellular enzymes including those involved in cellular metabolism and DNA replication. Mechanisms that underlie the tight control of iron levels are crucial in mediating the interaction between microorganisms and their host and hence, the spread of infection. Microorganisms including viruses, bacteria, and fungi have differing iron acquisition/utilization mechanisms to support their ability to acquire/use iron (e.g., from free iron and heme). These pathways of iron uptake are associated with promoting their growth and virulence and consequently, their pathogenicity. Thus, controlling microorganismal survival by limiting iron availability may prove feasible through the use of agents targeting their iron uptake pathways and/or use of iron chelators as a means to hinder development of infections. This review will serve to assimilate findings regarding iron and the pathogenicity of specific microorganisms, and furthermore, find whether treating infections mediated by such organisms via iron chelation approaches may have potential clinical benefit.

Genes, Pathways, and Mechanisms Involved in the Virulence of Mucorales

The order Mucorales is a group of ancient fungi with limited tools for gene manipulation. The main consequence of this manipulation unwillingness is the limited knowledge about its biology compared to other fungal groups. However, the emerging of mucormycosis, a fungal infection caused by Mucorales, is attracting the medical spotlight in recent years because the treatments available are not efficient in reducing the high mortality associated with this disease. The result of this renewed interest in Mucorales and mucormycosis is an extraordinarily productive effort to unveil their secrets during the last decade. In this review, we describe the most compelling advances related to the genetic study of virulence factors, pathways, and molecular mechanisms developed in these years. The use of a few genetic study models has allowed the characterization of virulence factors in Mucorales that were previously described in other pathogens, such as the uptake iron systems, the mechanisms of dimorphism, and azole resistances. More importantly, recent studies are identifying new genes and mechanisms controlling the pathogenic potential of Mucorales and their interactions with the host, offering new alternatives to develop specific strategies against mucormycosis.

Antifungal combinations in Mucorales: A microbiological perspective

Mucormycosis mostly affects immunocompromised patients and is associated with a high morbidity and mortality despite currently available treatments. In that context, combination therapy might be the key to a better outcome for these patients. Purpose of this review is to summarise and to discuss the current combination data obtained in vitro, in vivo in animal models of mucormycosis, and in patients. In vitro combination studies showed that most of the interactions between antifungal drugs were indifferent, even though that some synergistic interactions were achieved for the combination of echinocandins with either azoles or amphotericin B. Importantly, antagonism was never observed. Animal models of mucormycosis focused on infections caused by Rhizopus arrhizus, neglecting most other species responsible for human disease. In these experimental animal models, no strong interactions have been demonstrated, although a certain degree of synergism has been reported in some instances. Combinations of antifungals with non-antifungal drugs have also been largely explored in vitro and in animal models and yielded interesting results. In patients with ketoacidosis and rhino-orbito-cerebral infection, combination of polyene with caspofungin was effective. In contrast, despite promising experimental data, adjunctive therapy with the iron chelator deferasirox was unfavourable and was associated with a higher mortality than monotherapy with liposomal amphotericin B. More combinations have to be tested in vitro and a much larger panel of Mucorales species has to be tested in vivo to give a valuable statement if antifungal combination therapy could be an effective treatment strategy in patients with mucormycosis.

Mucormycosis of the Central Nervous System

Mucormycosis involves the central nervous system by direct extension from infected paranasal sinuses or hematogenous dissemination from the lungs. Incidence rates of this rare disease seem to be rising, with a shift from the rhino-orbital-cerebral syndrome typical of patients with diabetes mellitus and ketoacidosis, to disseminated disease in patients with hematological malignancies. We present our current understanding of the pathobiology, clinical features, and diagnostic and treatment strategies of cerebral mucormycosis. Despite advances in imaging and the availability of novel drugs, cerebral mucormycosis continues to be associated with high rates of death and disability. Emerging molecular diagnostics, advances in experimental systems and the establishment of large patient registries are key components of ongoing efforts to provide a timely diagnosis and effective treatment to patients with cerebral mucormycosis.

Deferiprone as adjunctive treatment for patients with invasive mucormycosis: A retrospective case series

Mucormycosis is a life-threatening disease requiring multimodal treatment with antifungals and surgery. The mortality rate remains high, prompting consideration of alternative treatment strategies. Deferiprone has in vitro activity against Mucorales, but its efficacy has never been evaluated in humans. Here, we retrospectively analyzed patients with confirmed mucormycosis who received deferiprone from 2011 to 2017. Five patients had hematologic malignancies and one was diabetic. The sites of infection included sinus-orbit-cerebral (67%), lung (17%), and disseminated infection (17%). Surgery was performed in 83% of cases and achieved local control for 33% of patients. A combination regimen of polyenes plus echinocandins was administered with stepdown treatment using posaconazole. The median duration of antifungal treatment was 86 days (range: 46-435 days) days. Deferiprone was given as adjunctive treatment with a median dose and duration of 100 mg/kd/day (range: 86.2-100 mg/kg/day) and 25 days (range: 15-215 days), respectively. Overall, deferiprone was well-tolerated. Successful outcomes were observed at 12-week follow-up for 67% of patients. The mortality rate at 180- day follow-up was 50%. Adjunctive therapy with deferiprone showed safety and tolerability.

A meta-analysis of survival factors in rhino-orbital-cerebral mucormycosis-has anything changed in the past 20 years?

BACKGROUND

Rhino-orbital-cerebral mucormycosis (ROCM) is an uncommon yet potentially lethal fungal infection. Although most cases originate from developing countries, an ageing population and increased prevalence of chronic illness may mean some clinicians practicing in developed countries will encounter ROCM cases in their careers. Yohai et al published a systematic review of 145 case reports from 1970 to 1993 assessing prognostic factors for patients presenting with ROCM. We present an updated review of the literature and assess whether survival outcomes have changed in the two decades since that seminal paper.

SEARCH STRATEGY

An extensive Medline literature search was performed for case reports published between 1994 and 2015.

RESULTS

In total, 210 published cases were identified from the literature review, of which 175 patients from 140 papers were included in this review. Fifty-five were female, with an overall mean age of 43 years. Overall survival rate was 59.5%, which was not significantly better than the previous series reported (60%) reported by Yohai et al. Survival rates in patients with chronic renal disease had improved, from 19% to 52%, and in patients with leukaemia (from 13% to 50%). Facial necrosis and hemiplegia remained poor prognostic indicators (33% and 39% survival rates, respectively). Early commencement of medical treatment related to better survival outcomes (61% if commenced within first 12 days of presentation, compared to 33% if after 13 days). Timing of surgery had less of an effect on overall survival. However, in 28 cases that did not receive any surgical treatment, survival was only 21%.

CONCLUSIONS

Although overall survival rates have not improved, survival in patients with renal disease were better, potentially due to the introduction of liposomal amphotericin B which is less nephrotoxic. Prompt recognition of ROCM, reversal of predisposing co-morbidities and aggressive medical treatment remain the cornerstone of managing this highly aggressive disease.

Host Sensing by Pathogenic Fungi

The ability to cause disease extends from the ability to grow within the host environment. The human host provides a dynamic environment to which fungal pathogens must adapt to in order to survive. The ability to grow under a particular condition (i.e., the ability to grow at mammalian body temperature) is considered a fitness attribute and is essential for growth within the human host. On the other hand, some environmental conditions activate signaling mechanisms resulting in the expression of virulence factors, which aid pathogenicity. Therefore, pathogenic fungi have evolved fitness and virulence attributes to enable them to colonize and infect humans. This review highlights how some of the major pathogenic fungi respond and adapt to key environmental signals within the human host.

Nutritional Immunity and Fungal Pathogenesis: The Struggle for Micronutrients at the Host-Pathogen Interface

All living organisms require certain micronutrients such as iron, zinc, manganese and copper for cellular function and growth. For human pathogens however, the maintenance of metal ion homeostasis is particularly challenging. This is because the mammalian host actively enforces extremes of micronutrient availability on potential microbial invaders-processes collectively termed nutritional immunity. The role of iron sequestration in controlling microbial infections is well established and, more recently, the importance of other metals including zinc, manganese and copper has been recognised. In this chapter, we explore the nutritional immune mechanisms that defend the human body against fungal infections and the strategies that these important pathogens exploit to counteract nutritional immunity and thrive in the infected host.

Investigation of the solid forms of deferasirox: solvate, co-crystal, and amorphous form

Five solid forms of deferasirox were prepared, characterized and preliminarily investigated.

Administration of Zinc Chelators Improves Survival of Mice Infected with Aspergillus fumigatus both in Monotherapy and in Combination with Caspofungin

Aspergillus fumigatus can infect immunocompromised patients, leading to high mortality rates due to the lack of reliable treatment options. This pathogen requires uptake of zinc from host tissues in order to successfully grow and cause virulence. Reducing the availability of that micronutrient could help treat A. fumigatus infections. In this study, we examined the in vitro effects of seven chelators using a bioluminescent strain of A. fumigatus 1,10-Phenanthroline and N,N,N',N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamine (TPEN) proved to be the chelators most effective at inhibiting fungal growth. Intraperitoneal administration of either phenanthroline or TPEN resulted in a significant improvement in survival and decrease of weight loss and fungal burden for immunosuppressed mice intranasally infected with A. fumigatus In vitro both chelators had an indifferent effect when employed in combination with caspofungin. The use of TPEN in combination with caspofungin also significantly increased survival compared to that when using these drugs individually. Our results suggest that zinc chelation may be a valid strategy for dealing with A. fumigatus infections and that both phenanthroline and TPEN could potentially be used either independently or in combination with caspofungin, indicating that their use in combination with other antifungal treatments might also be applicable.

Synergy and antagonism between iron chelators and antifungal drugs in Cryptococcus

Fungal infections remain very difficult to treat, and developing new antifungal drugs is difficult and expensive. Recent approaches therefore seek to augment existing antifungals with synergistic agents that can lower the therapeutic dose, increase efficacy and prevent resistance from developing. Iron limitation can inhibit microbial growth, and iron chelators have been employed to treat fungal infections. In this study, chequerboard testing was used to explore combinations of iron chelators with antifungal agents against pathogenic Cryptococcus spp. with the aim of determining how disruption to iron homeostasis affects antifungal susceptibility. The iron chelators ethylenediaminetetraacetic acid (EDTA), deferoxamine (DFO), deferiprone (DFP), deferasirox (DSX), ciclopirox olamine and lactoferrin (LF) were paired with the antifungal agents amphotericin B (AmB), fluconazole, itraconazole, voriconazole and caspofungin. All chelators except for DFO increased the efficacy of AmB, and significant synergy was seen between AmB and LF for all Cryptococcus strains. Addition of exogenous iron rescued cells from the antifungal effect of LF alone but could not prevent inhibition by AmB + LF, indicating that synergy was not due primarily to iron chelation but to other properties of LF that were potentiated in the presence of AmB. Significant synergy was not seen consistently for other antifungal-chelator combinations, and EDTA, DSX and DFP antagonised the activity of azole drugs in strains of Cryptococcus neoformans var. grubii. This study highlights the range of interactions that can be induced by chelators and indicates that most antifungal drugs are not enhanced by iron limitation in Cryptococcus.

Invasive rhino-orbito-cerebral mucormycosis in a diabetic patient - the need for prompt treatment

Mucormycosis is a rare life threatening fungal infection predominately seen in immunocompromised or diabetic patients. The following case is of a known type II diabetic patient who presented with sepsis and sudden unilateral loss of vision secondary to infective rhino-orbito-cerebral mucormycosis. Treatment of the condition required extensive surgical intervention and medical management for a life saving outcome.

Proven invasive pulmonary mucormycosis successfully treated with amphotericin B and surgery in patient with acute myeloblastic leukemia: a case report

Introduction

Invasive mucormycosis (zygomycosis) is the third most frequent fungal infection in patients with hematologic malignancies. It often results in a fatal outcome mainly due to the difficulty of early diagnosis and its resistance to antimycotics.

Case presentation

A 52-year-old Caucasian man was diagnosed with acute myeloblastic leukemia. Following the induction chemotherapy he developed febrile neutropenia. Meropenem (3×1000mg/day) was introduced empirically. A chest computed tomography showed soft-tissue consolidation change in his right upper lobe. A bronchoscopy was performed and the histology indicated invasive pulmonary aspergillosis based on fungal hypha detection. Also, high risk patients are routinely screened for invasive fungal infections using commercially available serological enzyme-linked immunosorbent assay tests: galactomannan and mannan (Bio-Rad, France), as well as anti-Aspergillus immunoglobulin G and/or immunoglobulin M and anti-Candida immunoglobulin G and/or immunoglobulin M antibodies (Virion-Serion, Germany). Galactomannan showed low positivity and voriconazole therapy (2×400mg/first day; 2×300mg/following days) was implemented. The patient became afebrile and a partial remission of disease was established. After 2 months, the patient developed a fever and a chest multi-slice computed tomography showed soft-tissue mass compressing his upper right bronchus. Voriconazole (2×400mg/first day; 2×300mg/following days) was reintroduced and bronchoscopy was repeated. Histologic examination of the new specimen was done, as well as a revision of the earlier samples in the reference laboratory and the diagnosis was switched to invasive pulmonary mucormycosis. The treatment was changed to amphotericin B colloidal dispersion (1×400mg/day). The complete remission of acute myeloblastic leukemia was verified after 2 months. During his immunerestitution, a high positivity of the anti-Aspergillus immunoglobulin M antibodies was found in a single serum sample and pulmonary radiography was unchanged. A lobectomy of his right upper pulmonary lobe was done and the mycology culture of the lung tissue sample revealed Rhizopus oryzae. He remained in complete remission for more than 1 year.

Conclusions

Invasive mucormycosis was successfully treated with amphotericin B, surgery and secondary itraconazole prophylaxis. As a rare disease invasive mucormycosis is not well understood by the medical community and therefore an improvement of education about prevention, diagnosis and treatment of invasive mucormycosis is necessary.

Epidemiology and treatment of mucormycosis

Mucormycosis is an uncommon but aggressive opportunistic fungal infection that afflicts patients with severe underlying immunosuppression, uncontrolled hyperglycemia and/or ketoacidosis, patients with iron overload resulting from frequent blood transfusions or blood disorders and occasionally healthy patients who are inoculated with fungal spores through traumatic injuries. The clinical presentation of mucormycosis is initially indistinguishable from other common infections, and if not diagnosed early and aggressively treated, it is almost always fatal. In this article we summarize recent changes in the epidemiology of mucormycosis, discuss diagnostic and clinical clues suggestive of the infection and provide a general strategy for managing the infection in the absence of data from well-controlled, prospective clinical trials.

[Iron and invasive fungal infection]

Iron is an essential factor for both the growth and virulence of most of microorganisms. As a part of the innate (or nutritional) immune system, mammals have developed different mechanisms to store and transport this element in order to limit free iron bioavailability. To survive in this hostile environment, pathogenic fungi have specific uptake systems for host iron sources, one of the most important of which is based on the synthesis of siderophores-soluble, low-molecular-mass, high-affinity iron chelators. The increase in free iron that results from iron-overload conditions is a well-established risk factor for invasive fungal infection (IFI) such as mucormycosis or aspergillosis. Therefore, iron chelation may be an appealing therapeutic option for these infections. Nevertheless, deferoxamine -the first approved iron chelator- paradoxically increases the incidence of IFI, as it serves as a xeno-siderophore to Mucorales. On the contrary, the new oral iron chelators (deferiprone and deferasirox) have shown to exert a deleterious effect on fungal growth both in vitro and in animal models. The present review focuses on the role of iron metabolism in the pathogenesis of IFI and summarises the preclinical data, as well as the limited clinical experience so far, in the use of new iron chelators as treatment for mucormycosis and invasive aspergillosis.

Fungal infection in solid organ recipients

In solid organ recipients, as with other immunosuppressed patients, infections by Candida spp. and Aspergillus spp. are the most frequent invasive mycoses. Infections by Cryptococcus spp. and fungi of the Mucorales order are less common. Infections by Fusarium spp. and Scedosporium spp. are very uncommon, except in patients undergoing hematopoietic stem cell transplant and patients with prolonged neutropenia. The risk factors for fungal infection are immunosuppression, surgery, viral co-infection, and environmental exposure. Diagnosis is challenging: blood culture is of little use, except in candidiasis and cryptococcosis, and the poor accuracy of antigen-based techniques, except in cryptococcosis, favors widespread use of empirical therapy. A delay in the initiation of therapy increases the already high mortality of these infections. The agents used to treat fungal infection are azoles, echinocandins, and lipid amphotericin. Administration depends on antifungal activity, drug-drug interactions with calcineurin inhibitors, and safety profiles (effects on grafts and other side effects).

Diagnosis and treatment of mucormycosis in patients with hematological malignancies: guidelines from the 3rd European Conference on Infections in Leukemia (ECIL 3)

Mucormycosis is an emerging cause of infectious morbidity and mortality in patients with hematologic malignancies. However, there are no recommendations to guide diagnosis and management. The European Conference on Infections in Leukemia assigned experts in hematology and infectious diseases to develop evidence-based recommendations for the diagnosis and treatment of mucormycosis. The guidelines were developed using the evidence criteria set forth by the American Infectious Diseases Society and the key recommendations are summarized here. In the absence of validated biomarkers, the diagnosis of mucormycosis relies on histology and/or detection of the organism by culture from involved sites with identification of the isolate at the species level (no grading). Antifungal chemotherapy, control of the underlying predisposing condition, and surgery are the cornerstones of management (level A II). Options for first-line chemotherapy of mucormycosis include liposomal amphotericin B and amphotericin B lipid complex (level B II). Posaconazole and combination therapy of liposomal amphotericin B or amphotericin B lipid complex with caspofungin are the options for second line-treatment (level B II). Surgery is recommended for rhinocerebral and skin and soft tissue disease (level A II). Reversal of underlying risk factors (diabetes control, reversal of neutropenia, discontinuation/taper of glucocorticosteroids, reduction of immunosuppressants, discontinuation of deferroxamine) is important in the treatment of mucormycosis (level A II). The duration of antifungal chemotherapy is not defined but guided by the resolution of all associated symptoms and findings (no grading). Maintenance therapy/secondary prophylaxis must be considered in persistently immunocompromised patients (no grading).

Donor-derived fungal infections in organ transplant recipients: guidelines of the American Society of Transplantation, infectious diseases community of practice

Donor-derived fungal infections can be associated with serious complications in transplant recipients. Most cases of donor-derived candidiasis have occurred in kidney transplant recipients in whom contaminated preservation fluid is a commonly proposed source. Donors with cryptococcal disease, including those with unrecognized cryptococcal meningoencephalitis may transmit the infection with the allograft. Active histoplasmosis or undiagnosed and presumably asymptomatic infection in the donor that had not resolved by the time of death can result in donor-derived histoplasmosis in the recipient. Potential donors from an endemic area with either active or occult infection can also transmit coccidioidomycosis. Rare instances of aspergillosis and other mycoses, including agents of mucormycosis may also be transmitted from infected donors. Appropriate diagnostic evaluation and prompt initiation of appropriate antifungal therapy are warranted if donor-derived fungal infections are a consideration. This document discusses the characteristics, evaluation and approach to the management of donor-derived fungal infections in organ transplant recipients.

Targeting iron assimilation to develop new antibacterials

INTRODUCTION

Since the first application of antibiotics to treat bacterial infections, the development and spread of resistance has been a persistent threat. An ever evolving pipeline of next-generation therapeutics is required for modern medicine to remain one step ahead of pathogens.

AREAS COVERED

This review describes recent efforts to develop drugs that interrupt the assimilation of iron by bacteria: a process that is vital to cellular homeostasis and is not currently targeted by antibiotics used in the clinic. This review also covers the mechanisms by which bacteria acquire iron for their environment, and details efforts to intervene in these processes, using small molecule inhibitors that target key steps in these pathways, with a special emphasis on recent advances published during the 2010 - 2012 period.

EXPERT OPINION

For decades, the routes used by bacteria to assimilate iron from host and environmental settings have been the subject of intense study. While numerous investigations have identified inhibitors of these pathways, many have stopped short of translating the in vitro results to in vivo proof of concept experiments. The extension of preliminary findings in this manner will significantly increase the impact of the field.

Combination therapy for mucormycosis: why, what, and how?

The high mortality rate of mucormycosis with currently available monotherapy, particularly in hematology patients, has stimulated interest in studying novel combinations of antifungal agents to determine whether superior outcomes might be achieved. Combination lipid polyene-echinocandin therapy is the most promising of such regimens based on safety profile, the availability of parenteral formulations of echinocandins, their synergy in murine models of mucormycosis, and observational clinical data that are concordant. Other options include combination lipid polyene plus deferasirox or posaconazole therapy. Definitive, randomized, placebo-controlled phase III clinical trials are needed to determine whether combination therapy with any of these options is superior to monotherapy. Until such studies are conducted, clinicians will continue to be placed in the unacceptable position of not knowing if and when to administer combination therapy. Such a state of confusion may lead to undertreatment if combination therapy is indeed superior but is not used and, conversely, may lead to unacceptable toxicity and cost to patients if combination therapy is not superior but is used. It is critical that sponsors step forward with funding to conduct these clinical trials to determine whether outcomes from these devastating infections can be improved.

Importance of pharmacokinetic considerations for selecting therapy in the treatment of invasive fungal infections

Invasive fungal infections continue to be a significant cause of morbidity and mortality among at-risk patients. Over the last decade, the epidemiology of invasive mycoses has been defined by increasing rates of infection caused by azole-resistant yeast (Candida glabrata, Candida krusei), Aspergillus, and in some centers, non-Aspergillus moulds, such as Fusarium species, Scedosporium species, and Mucorales. Early and appropriate antifungal therapy is crucial for a favorable clinical outcome. When selecting antifungal therapy--especially during the initial acute phases of treatment--spectrum of activity and pharmacokinetic characteristics are key treatment considerations. Important pharmacokinetic considerations for selecting antifungal therapy in the treatment of invasive fungal infections include drug-drug interactions and variability in adsorption that may limit efficacy during the early phase of treatment, poor oral availability, and variable tissue distribution. A patient's underlying condition and pharmacogenetics also may affect the pharmacokinetics of antifungal drugs, resulting in interpatient pharmacokinetic differences.

Risk factors for mortality in patients with mucormycosis

Optimal clinical care and clinical investigation of patients with mucormycosis are limited by absence of controlled trials, and absence of well-defined predictors of mortality or clinical response. The Deferasirox-AmBisome Therapy for mucormycosis (DEFEAT Mucor) study was the first randomized clinical trial conducted on patients with mucormycosis, and demonstrated that adjunctive deferasirox therapy did not improve outcomes of the disease. The current study describes clinical factors from the 20 patients enrolled to identify those associated with 90-day mortality of the 11 (55%) patients who died by day 90. Age, diabetes mellitus, transplant status, or antifungal therapy were not associated with mortality. However, active malignancy or neutropenia at enrollment were associated with increased mortality. Pulmonary infection was linked with lower Kaplan-Meier survival compared to non-pulmonary infection. Higher baseline serum concentrations of iron and ferritin were also associated with mortality. No patient who progressed clinically during the first 14 days of study therapy survived; however, many patients who clinically improved during that time did not survive to 90 days. In contrast, day 30 clinical response was predictive of 90-day survival. These factors may be useful in defining enrollment randomization stratification critieria for future clinical trials, and in supporting clinical care of patients with mucormycosis.

[Antifungal therapy update: new drugs and medical uses]

Increases in the rates of fungal infections, as well as their associated morbidity and mortality has led to a need for additional antifungal agents. The most common serious fungal agents in immunosuppressed and critically ill patients are Candida spp. and Aspergillus spp., although other emerging fungi must be considered. Rational, early systemic antifungal treatment should be based on diagnostic imaging techniques and conventional mycological and non-culture-based procedures. While the availability of new therapeutic options is an important advance, antifungal therapy has become increasingly complex. In addition to the available antifungal armamentarium, recent research has resulted in the introduction of three new antifungal agents: micafungin, anidulafungin, and posaconazole. This article provides an update, based on the latest scientific evidence, of the clinical efficacy, pharmacokinetics, safety and dosing of antifungal drugs administered in the management of Candida spp., Aspergillus spp., Cryptococcus spp., Zygomycetes, Scedosporium spp. and Fusarium spp.

Uncommon mold infections in hematological patients: epidemiology, diagnosis and treatment

Invasive fungal diseases continue to be an important cause of morbidity and mortality in immunosuppressed patients. This is of particular interest, since the progress we made in the treatment of underlying malignancies has led to an increase of the number of persons 'at high risk'. During the last few years, several changes in clinical practice in hematology (new immunosuppressants, hematopoietic stem cell transplants) have influenced the epidemiology of invasive fungal diseases; in particular, cases due to some uncommon etiologic agents are being increasingly reported, making it even more urgent to reconsider differential diagnoses in high-risk patients. A better understanding of epidemiology, risk factors and prognosis appears to be crucial to analyze prevention and diagnostic strategies, as well as to guarantee an early and adequate treatment.

Immunotherapy of infections caused by rare filamentous fungi

Invasive fungal infections caused by rare filamentous fungi constitute a significant cause of morbidity and mortality in patients with defective immune responses. Despite the advent of new antifungal agents, the problem is escalating as the number of susceptible hosts increases and virulent, more resistant fungal strains emerge. There is evidence that reconstitution of the host immune function is a major contributor to the resolution of these infections. Therapeutic modalities aimed at increasing phagocyte numbers, such as granulocyte transfusions, stimulating the immune response, such as administration of haematopoietic growth factors and other proinflammatory cytokines, or indirectly augmenting immune function have shown promising results in the preclinical setting. Because of the rarity of the infections, multicentre clinical trials are needed to demonstrate the efficacy and safety of the new immunomodulating approaches.

The Deferasirox-AmBisome Therapy for Mucormycosis (DEFEAT Mucor) study: a randomized, double-blinded, placebo-controlled trial

OBJECTIVES

Host iron availability is fundamental to mucormycosis pathogenesis. The combination of liposomal amphotericin B (LAmB) and deferasirox iron chelation therapy synergistically improved survival in diabetic mice with mucormycosis. To determine the safety of combination deferasirox plus LAmB therapy for mucormycosis, a multicentred, placebo-controlled, double-blinded clinical trial was conducted.

METHODS

Twenty patients with proven or probable mucormycosis were randomized to receive treatment with LAmB plus deferasirox (20 mg/kg/day for 14 days) or LAmB plus placebo (NCT00419770, clinicaltrials.gov). The primary analyses were for safety and exploratory efficacy.

RESULTS

Patients in the deferasirox arm (n=11) were more likely than those in the placebo arm (n=9) to have active malignancy, neutropenia and corticosteroid therapy, and were less likely to receive concurrent non-study antifungal therapy. Reported adverse events and serious adverse events were similar between the groups. However, death was more frequent in the deferasirox than in the placebo arm at 30 days (45% versus 11%, P=0.1) and 90 days (82% versus 22%, P=0.01). Global success (alive, clinically stable, radiographically improved) for the deferasirox arm versus the placebo arm at 30 and 90 days, respectively, was 18% (2/11) versus 67% (6/9) (P=0.06) and 18% (2/11) versus 56% (5/9) (P=0.2).

CONCLUSIONS

Patients with mucormycosis treated with deferasirox had a higher mortality rate at 90 days. Population imbalances in this small Phase II study make generalizable conclusions difficult. Nevertheless, these data do not support a role for initial, adjunctive deferasirox therapy for mucormycosis.