Monocyte-mediated damage to Rhizopus oryzae hyphae in vitro

Synergistic action of lactoferrin and its derived functional fragments as a promising therapeutic agent in combating mucormycosis

Aim: Currently, we have limited armamentarium of antifungal agents against Mucorales. There is an urgent need to discover novel antifungal agents that are effective, safe and affordable. Materials & methods: In this study, the anti-Mucorale action of native lactoferrin (LF) and its functional fragments CLF, RR6 and LFcin against three common Mucorale species are reported. The synergistic action of LF with antifungal agents like amphotericin B, isavuconazole and posaconazole was analyzed using checkerboard technique. Results: All the three mucor species showed inhibition when treated with fragments. The checkerboard assay confirmed that native LF showed the best synergistic action against Mucorales in combination with Amphotericin B. Conclusion: These results highlight the potential therapeutic value of native LF against Mucorales.

A Retrospective Observational Study on the Comparison of Different Diagnostic Modalities of Post-COVID Mucormycosis

Background Mucormycosis, attributed to a group of molds known as mucormycosis, is a rare yet life-threatening fungal infection often colloquially referred to as black fungus. While its incidence notably surged during the second wave of COVID-19 infections in India, it's essential to recognize that mucormycosis was a significant concern even before the advent of the pandemic. Understanding the prevalence and characteristics of this infection in the pre-COVID era provides a crucial context for evaluating its impact and dynamics during the pandemic. Multiple diagnostic methods, such as potassium hydroxide (KOH) mount, culture, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and histopathological examination (HPE), are available for identifying this lethal infection. The primary objective of this study is to ascertain the sensitivity of various diagnostic methods for mucormycosis and to analyze the comparative effectiveness of microbiological versus histopathological diagnoses. Methods We conducted a retrospective observational study spanning six months, from May 2021 to October 2021, encompassing all mucormycosis cases meeting the inclusion criteria and diagnosed via histopathological examination (HPE) in the departments of pathology and microbiology. Microbiological tests were performed prior to the histopathological examinations. Sensitivity was assessed through statistical analysis, and the relationship between microbiological and histopathological diagnoses was evaluated using the chi-square test. Results Biopsy samples of 77 patients were collected, comprising 56 male and 21 female patients. Regarding age distribution, most patients fell within the 41-60 age bracket, while the smallest proportion was over 60 years old. The sensitivity and specificity of histopathological diagnosis, confirmed with periodic acid-Schiff (PAS) and Grocott-Gomori's methenamine silver (GMS) staining, both recorded a flawless 100%. KOH mount sensitivity stood at 88.3%, while fungal culture and MALDI-TOF exhibited sensitivities of 75.3%. Histopathological analysis revealed that 17% of cases displayed minimal fungal hyphae alongside necrotic tissue, whereas 58% exhibited abundant fungal hyphae accompanied by inflammatory cells. Additionally, absolute neutrophilia was observed in 55% of cases. Conclusions In our study, histopathology and KOH mount emerged as not only compassionate but also cost-effective diagnostic tools for identifying mucormycosis. The economic aspect of these diagnostic methods is highlighted in the results section to provide a comprehensive understanding of their cost-effectiveness. Additionally, we utilized MALDI-TOF MS as a straightforward, economically viable, and expeditious method specifically for confirming the fungal subtype in mucormycosis cases. The rationale behind choosing either MALDI-TOF MS or KOH for the diagnosis is elucidated, contributing to a clearer interpretation of our diagnostic approach. Furthermore, our findings indicate that absolute neutrophilia consistently manifests in 55% of mucormycosis cases.

Invasive Fungal Rhinosinusitis: Clinical and Surgical Factors Affecting Its Prognosis and Disease-Specific Morality

PURPOSE

The purpose of this study is to discover factors that determine mortality in patients with invasive fungal rhinosinusitis.

METHODS

This retrospective study included 17 patients diagnosed with invasive fungal rhinosinusitis and who had undergone treatment in our department, including both surgical and medical management between January 2020 and October 2020. There were four male patients and 13 female patients whose mean age was 46 ± 15.67 years, ranging from 20 to 70 years. All the patients were immune-compromised because of diabetes mellitus. We studied the factors affecting the mortality of patients affected with this disease; it included the extent of disease (paranasal sinus, palatal, orbital, or intracranial involvement), serum glucose level (SGL), and C-reactive protein (CRP) levels.

RESULTS

Only one patient had paranasal sinus involvement alone, but the patient became disease-free after treatment. The disease-specific mortality rate was two (33.3%) of six patients with palatal involvement and four (50%) of eight patients with intracranial involvement where four patients did not have disease control at the time of discharge and did not follow up. The death rate in orbital involvement was 20% (three of 15 patients) and five patients with intra-orbital involvement left the hospital against medical advice. The analysis of data demonstrated that only intracranial (p = 0.01) involvement in addition to the nasal cavity and paranasal sinus involvement had a statistically significant effect on survival rate unlike intra-orbital (p = 0.510) and palatal involvement (p = 0.171).

CONCLUSION

Early endoscopic nasal inspection, diagnosis, and treatment are critical for disease-specific mortality in invasive fungal rhinosinusitis since orbital or cerebral involvement is linked to a poor prognosis. Patients who come with uncontrolled diabetes and ophthalmological and palatal involvement with positive findings on nasal examination should necessitate urgent histopathological and radiological workup.

Surge of mucormycosis during the COVID-19 pandemic

Patients with respiratory viral infections are more likely to develop co-infections leading to increased fatality. Mucormycosis is an epidemic amidst the COVID-19 pandemic that conveys a 'double threat' to the global health fraternity. Mucormycosis is caused by the Mucorales group of fungi and exhibits acute angioinvasion generally in immunocompromised patients. The most familiar foci of infections are sinuses (39%), lungs (24%), and skin tissues (19%) where the overall dissemination occurs in 23% of cases. The mortality rate in the case of disseminated mucormycosis is found to be 96%. Symptoms are mostly nonspecific and often resemble other common bacterial or fungal infections. Currently, COVID-19-associated mucormycosis (CAM) is being reported from a number of countries such as the USA, Turkey, France, Mexico, Iran, Austria, UK, Brazil, and Italy, while India is the hotspot for this deadly co-infection, accounting for approximately 28,252 cases up to June 8, 2021. It strikes patients within 12-18 days after COVID-19 recovery, and nearly 80% require surgery. Nevertheless, the mortality rate can reach 94% if the diagnosis is delayed or remains untreated. Sometimes COVID-19 is the sole predisposing factor for CAM. Therefore, this study may provide a comprehensive resource for clinicians and researchers dealing with fungal infections, intending to link the potential translational knowledge and prospective therapeutic challenges to counter this opportunistic pathogen.

Mucormycosis as Post Coronavirus Disease Complication

Mucormycosis is called as black fungus, which is caused by fungus belonged to Mucorales. If this fungus, effects healthy individuals it won't cause any serious complications, but it may cause life-threatening issues when Mucorales affects individuals who have low immunity. The mortality rate of black fungus is more than 50%, and it may also range till 100% if the individual is having any preexisting or chronic disease. This was the case of a 55-year-old male patient complaint of having generalized pain in the maxillary teeth bilaterally and suffering fullness in the maxillary sinus. To check on other possible diseases, doctors have conducted other diagnosis tests, and orthopantomogram revealed in the diagnosis that there was the presence of haziness in the left maxillary sinus, which looked like an incompletely formed soap bubble and additionally he diagnosed with coronavirus disease positive. Then, doctors suggested a chest computerized tomography (CT) along with head CT excluding the brain and further investigation of this case was given below in detail. The report reveals acute necrotizing suppurative sinusitis with dead bony tissue, soft-tissue necrosis with fungal infestation showing broad hyphae with right-angle branching suggestive of mucormycosis.

Is the production of reactive oxygen and nitrogen species by macrophages associated with better infectious control in female mice with experimentally disseminated and pulmonary mucormycosis?

Different levels of resistance against Rhizopus oryzae infection have been observed between inbred (BALB/c) and outbred (Swiss) mice and are associated with the genetic background of each mouse strain. Considering that macrophages play an important role in host resistance to Rhizopus species, we used different infectious outcomes observed in experimental mucormycosis to identify the most efficient macrophage response pattern against R. oryzae in vitro and in vivo. For this, we compared BALB/c and Swiss macrophage activity before and after intravenous or intratracheal R. oryzae infections. The production of hydrogen peroxide (H2O2) and nitric oxide (NO) was determined in cultures of peritoneal (PMΦ) or alveolar macrophages (AMΦ) challenged with heat-killed spores of R. oryzae. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10) were measured to confirm our findings. Naïve PMΦ from female BALB/c mice showed increased production of H2O2, TNF-α, and IL-10 in the presence of heat-killed spores of R. oryzae. Naïve PMΦ from female Swiss mice were less responsive. Naïve AMΦ from the two strains of female mice were less reactive to heat-killed spores of R. oryzae than PMΦ. After 30 days of R. oryzae intravenous infection, lower fungal load in spleen from BALB/c mice was accompanied by higher production of H2O2 by PMΦ compared with Swiss mice. In contrast, AMΦ from BALB/c mice showed higher production of NO, TNF-α, and IL-10 after 7 days of intratracheal infection. The collective findings reveal that, independent of the female mouse strain, PMΦ is more reactive against R. oryzae upon first contact than AMΦ. In addition, increased PMΦ production of H2O2 at the end of disseminated infection is accompanied by better fungal clearance in resistant (BALB/c) mice. Our findings further the understanding of the parasite-host relationship in mucormycosis.

Interleukin-37: A Link Between COVID-19, Diabetes, and the Black Fungus

The COVID-19 pandemic involved millions of people and diabetes was identified as an associated comorbidity. Initiation of systemic corticosteroids in patients suffering from severe COVID-19 was associated with lower mortality. A surge of invasive fungal infections of the maxillofacial region, namely mucormycosis, was linked to a deadly infection known as black fungus. Black fungus, diabetes, corticosteroids, and coronavirus disease 2019 (COVID-19) all have a dysregulated immune response in common, which partly could also be attributed to interleukin 37 (IL-37). IL-37, a new cytokine of the IL-1 family, known for broadly reducing innate inflammation as well as acquired immune responses. The use of corticosteroids in diabetic COVID-19 patients, crowded hospitals, and lack of medical oxygen should be carefully considered to reduce COVID-associated secondary infections.

The Past, Present and Future of COVID-19 Associated Mucormycosis: A Rapid Review

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2, which is known for the multiple mutations and forms that have rapidly spread across the world. With the imminent challenges faced by low- and middle-income countries in curbing the public health fallbacks due to limited resources, mucormycosis emerged as a fungal infection associated with high mortality. In this rapid review, we explored MEDLINE, Cochrane, Web of Science, WHO Global Database, and the search engine—Google Scholar for articles listed until July 2021 and presented a narrative synthesis of findings from 39 articles. The epidemiology, causative factors, incidence parameters, pharmacological treatment, and recommendations for low- and middle-income countries are enlisted. This study concludes that a majority of the globally reported COVID-19 associated mucormycosis cases stemmed from India. Individuals receiving systemic corticosteroids or who have a history of diabetes mellitus are more prone to contracting the disease. Public health authorities in LMIC are recommended to strengthen antifungal therapies for COVID-19 associated mucormycosis and to strategize reduction in diabetes mellitus prevalence.

Rhino-orbito-cerebral mucormycosis during the COVID-19 third wave in 2021: an Egyptian preliminary report from a single tertiary hospital

COVID-19 is a pandemic disease which predominantly affects the respiratory system with high critical care mortality and morbidity; however, it also causes multi-organ dysfunction in a subset of patients. Although causality between COVID-19 and mucormycosis remains unclear, many factors including glucocorticoids, worsening of blood glucose control, and viral-induced lymphopenia have been attributed to cause mucormycosis in patients with COVID-19. In COVID-19 patients, especially those who need oxygen support, inflammatory and cytokine storm or usage of steroids make the immune system weak. This may pave the way for opportunistic infections including mucormycosis. We report fourteen cases of COVID-19 infection, who developed rhino-orbito-cerebral mucormycosis, during treatment. Early recognition of this life-threatening infection is the key to allow for optimal treatment and improved outcomes.

COVID-19-associated-mucormycosis: possible role of free iron uptake and immunosuppression

COVID-19-associated-mucormycosis, commonly referred to as the "Black Fungus," is a rare secondary fungal infection in COVID-19 patients prompted by a group of mucor molds. Association of this rare fungal infection with SARS-CoV-2 infection has been declared as an endemic in India, with minor cases in several other countries around the globe. Although the fungal infection is not contagious like the viral infection, the causative fungal agent is omnipresent. Infection displays an overall mortality rate of around 50%, with many other secondary side effects posing a potential threat in exacerbating COVID-19 mortality rates. In this review, we have accessed the role of free iron availability in COVID-19 patients that might correlate to the pathogenesis of the causative fungal agent. Besides, we have analyzed the negative consequences of using immunosuppressive drugs in encouraging this opportunistic fungal infection.

Lactoferrin, a potential iron-chelator as an adjunct treatment for mucormycosis - A comprehensive review

Mucormycosis is a deadly infection which is caused by fungi of the order Mucorales including species belonging to the genus Rhizopus, Mucor, Mycocladus, Rhizomucor, Cunninghamella, and Apophysomyces. Despite antifungal therapy and surgical procedures, the mortality rate of this disease is about 90-100% which is exceptionally high. The hypersensitivity of patients with raised available serum iron indicates that the Mucorales are able to use host iron as a critical factor of virulence. This is because iron happens to be a crucial element playing its role in the growth of cells and development. In this review, we have described Lactoferrin (Lf) as a potential iron-chelator. Lf is a naturally occurring glycoprotein which is expressed in most of the biological fluids. Moreover, Lf possesses exclusive anti-inflammatory effects along with several anti-fungal effects that could prove to be helpful to the pathological physiology of inexorable mucormycosis cases. This literature summarises the biological insights into the Lf being considered as a potential fungistatic agent and an immune regulator. The review also proposes that unique potential of Lf as an iron-chelator can be exploited as the adjunct treatment for mucormycosis infection.

COVID-19-associated mucormycosis: An updated systematic review of literature

In its wake, the COVID-19 pandemic has ushered in a surge in the number of cases of mucormycosis. Most cases are temporally linked to COVID-19; hence, the entity is described as COVID-19-associated mucormycosis (CAM). The present systematic review was undertaken to provide an up-to-date summary of the hitherto available literature on CAM. PubMed, Scopus and Google Scholar databases were systematically searched using appropriate keywords till 14 May 2021, to identify case reports/case series pertaining to mucormycosis in patients with COVID-19. Relevant data extracted included demographic characteristics, comorbidity profile, clinical category of mucormycosis, glucocorticoid use, treatment offered and patient outcome. We identified 30 case reports/case series, pooling data retrieved from 99 patients with CAM. Most cases were reported from India (72%). The majority of the patients was male (78%) and had diabetes mellitus (85%). A prior history of COVID-19 was present in 37% patients with mucormycosis developing after an initial recovery. The median time interval between COVID-19 diagnosis and the first evidence of mucormycosis infection or CAM diagnosis was 15 days. Glucocorticoid use was reported in 85% of cases. Rhino-orbital mucormycosis was most common (42%), followed by rhino-orbito-cerebral mucormycosis (24%). Pulmonary mucormycosis was observed in 10 patients (10%). The mortality rate was 34%; the use of adjunct surgery, which was undertaken in 81% of patients, was associated with better clinical outcomes (p < .001). In conclusion, CAM is an emerging problem necessitating increased vigilance in COVID-19 patients, even those who have recovered. CAM portends a poor prognosis and warrants early diagnosis and treatment.

Robust Phagocyte Recruitment Controls the Opportunistic Fungal Pathogen Mucor circinelloides in Innate Granulomas In Vivo

Mucormycosis is an emerging fungal infection with extremely high mortality rates in patients with defects in their innate immune response, specifically in functions mediated through phagocytes. However, we currently have a limited understanding of the molecular and cellular interactions between these innate immune effectors and mucormycete spores during the early immune response. Here, the early events of innate immune recruitment in response to infection by Mucor circinelloides spores are modeled by a combined in silico modeling approach and real-time in vivo microscopy. Phagocytes are rapidly recruited to the site of infection in a zebrafish larval model of mucormycosis. This robust early recruitment protects from disease onset in vivoIn silico analysis identified that protection is dependent on the number of phagocytes at the infection site, but not the speed of recruitment. The mathematical model highlights the role of proinflammatory signals for phagocyte recruitment and the importance of inhibition of spore germination for protection from active fungal disease. These in silico data are supported by an in vivo lack of fungal spore killing and lack of reactive oxygen burst, which together result in latent fungal infection. During this latent stage of infection, spores are controlled in innate granulomas in vivo Disease can be reactivated by immunosuppression. Together, these data represent the first in vivo real-time analysis of innate granuloma formation during the early stages of a fungal infection. The results highlight a potential latent stage during mucormycosis that should urgently be considered for clinical management of patients.IMPORTANCE Mucormycosis is a dramatic fungal infection frequently leading to the death of patients. We know little about the immune response to the fungus causing this infection, although evidence points toward defects in early immune events after infection. Here, we dissect this early immune response to infectious fungal spores. We show that specialized white blood cells (phagocytes) rapidly respond to these spores and accumulate around the fungus. However, we demonstrate that the mechanisms that enable phagocytes to kill the fungus fail, allowing for survival of spores. Instead a cluster of phagocytes resembling an early granuloma is formed around spores to control the latent infection. This study is the first detailed analysis of early granuloma formation during a fungal infection highlighting a latent stage that needs to be considered for clinical management of patients.

The mucormycete-host interface

Mucormycosis is a fungal infection with fulminant angioinvasion leading to high morbidity and mortality in susceptible individuals. The major predisposing conditions are uncontrolled diabetes, neutropenia, malignancies, receipt of a transplant and traumatic injury [1]. Over the past decade, mucormycosis has become an emerging fungal infection due to the increase in patient groups presenting with these pre-disposing conditions and our medical advances in diagnosing the infection [2-4]. Yet, we currently lack clinical interventions to treat mucormycosis effectively. This in turn is due to a lack of understanding of mucormycosis pathogenesis. Here, we discuss our current understanding of selected aspects of interactions at the mucormycete-host interface. We will highlight open questions that might guide future research directions for investigations into the pathogenesis of mucormycosis and potential innovative therapeutic approaches.

Clinical features and diagnosis of chronic pulmonary aspergillosis in Chinese patients

Chronic pulmonary aspergillosis (CPA) has recently been recognized as a significant global health burden. In China, the diagnosis of CPA is still unfamiliar to most doctors. The aim of this study was to demonstrate the clinical manifestations and diagnoses of CPA in China.A multidisciplinary team of doctors retrospectively screened 690 records of patients diagnosed with pulmonary aspergillosis from January 2000 to December 2016 at Peking Union Medical College Hospital, Beijing, China. Of these, 69 patients were diagnosed with CPA. The patients' clinical characteristics were then retrieved and analyzed. Demographic, laboratory, and radiological data for these patients were compared by CPA type.Of the 69 patients diagnosed with CPA, 10 patients were diagnosed with chronic cavitary pulmonary aspergillosis (CCPA), 15 patients with semi-invasive aspergillosis (SAIA), 41 patients with simple aspergilloma, and 3 patients with Aspergillus nodule. Further, 53.3% of the SAIA patients were obviously immunocompromised, and 60% of the CCPA patients, 26.7% of the SAIA patients, 7.3% of the simple aspergilloma cases were mildly immunocompromised. Previous underlying lung abnormalities were observed in 20% of CCPA patients, 53.3% of SAIA patients, and 80.5% of simple aspergilloma patients. The most common symptoms in the CPA patients were cough (92.8%), hemoptysis (63.8%), chronic sputum (23.2%), and fever (17.4%). The most common computerized tomography abnormalities were cavities (94.2%), nodule (84.1%), consolidation (4.3%), pleural thickening (2.9%), and infiltration (2.9%). CCPA, SAIA and simple aspergilloma patients were significantly different with respect to their course before diagnosis, constitutional symptoms, fever, hemoptysis, breathlessness, white blood cell count, erythrocyte sedimentation rate, high-sensitivity C-reactive protein count, presence of nodule, and presence of a solitary lesion (all P < .05). Furthermore, SAIA patients had a significantly shorter course before diagnosis and a significantly higher white blood cell count compared with CCPA patients (both P < .01).In China, underlying systemic immunocompromising conditions and lung diseases with mechanical impediments contribute to CPA. Simple aspergillosis was the most common diagnosis in CPA patients. The imaging characteristics of simple aspergillosis and Aspergillus nodules were quite discriminable, while CCPA, and SAIA were similar in their clinical and radiological features. Distinguishing between CCPA and SAIA depends mainly on the physician's clinical judgment.

Rare complication of bronchoesophageal fistula due to pulmonary mucormycosis after induction chemotherapy for acute myeloid leukemia: a case report

Background

Mucormycosis is a rare and life-threatening invasive fungal infection. Pulmonary mucormycosis commonly occurs in patients with severe neutropenia. Typically, pulmonary mucormycosis causes tissue necrosis resulting from angioinvasion and subsequent thrombosis, so most cases can occur with necrotizing pneumonia and/or hemoptysis. Some complex cases may invade adjacent organs, such as the mediastinum, pericardium, and chest wall. However, to the best our knowledge there is little known regarding bronchoesophageal fistula due to pulmonary mucormycosis after induction chemotherapy for acute myeloid leukemia. We present a case report about this unusual presentation.

Case presentation

A 51-year-old Korean man was diagnosed as having acute myeloid leukemia and received induction chemotherapy. After prolonged severe neutropenia, he complained of coughing with aspiration. Imaging showed a bronchoesophageal fistula with extensive necrotizing pneumonia in the middle and lower lobes of his right lung. Bronchoscopy showed near total tissue necrosis in the middle lobe of his right lung, creating an orifice. A bronchial scope was passed through and was able to be connected with his esophagus; a bronchial wall biopsy was performed. Esophagoscopy revealed a large linear defect of his esophageal wall 30 cm from the incision that may have connected with the bronchus. A bronchial biopsy showed typical hyphae with necrotic tissue, indicating pulmonary mucormycosis. He was given amphotericin B, and a wide excision of lung and esophagus was planned. However, he suddenly died due to massive hemoptysis.

Conclusion

Here we present an extremely rare case of bronchoesophageal fistula with severe necrotizing pneumonia due to pulmonary mucormycosis.

The burden of mucormycosis in HIV-infected patients: A systematic review

OBJECTIVES

Mucormycosis is an invasive fungal infection afflicting immunocompromised patients, causing a significant degree of morbidity and mortality. The purpose of the study was to provide a comprehensive analysis describing the epidemiology and outcome of mucormycosis in the scenario of HIV infection.

METHODS

We systematically searched PubMed for reports about mucormycosis associated with HIV. Eligible studies describe the predisposing factor, clinical form, treatment, and survival outcome.

RESULTS

We included 61 articles from 212 reviewed abstracts, corresponding to 67 cases. Patients were mostly men (68.2%) with a median CD4(+) count of 47 [IQR 17-100] cells/mm(3). Intravenous drug use (50%), neutropenia (29.7%) and corticosteroid use (25%) were the predominant associated factors. The main clinical forms were disseminated (20.9%), renal (19.4%), and rhino-cerebral (17.9%). Rhizopus (45.5%) and Lichtheimia spp (30.3%) were the main fungal isolates. Treatment consisted of antifungal therapy and surgery in 38.8%. Overall mortality rate was 52.2%, and varied with the site of infection: 92.9% for disseminated disease, 62.5% for cerebral disease, 60% for pulmonary infection, and 36.4% for cutaneous infection. Survival was worse for those who did not initiate antifungals (p = .04), who were antiretroviral naïve (p = .01), who were admitted to ICU (p = .003) or had disseminated disease (p = .007).

CONCLUSIONS

Mucormycosis is a life-threatening infection in HIV patients and clinician should be aware of this co-infection in the differential diagnosis of HIV opportunistic infections.

Calcineurin orchestrates dimorphic transitions, antifungal drug responses and host-pathogen interactions of the pathogenic mucoralean fungus Mucor circinelloides

Calcineurin plays essential roles in virulence and growth of pathogenic fungi and is a target of the natural products FK506 and Cyclosporine A. In the pathogenic mucoralean fungus Mucor circinelloides, calcineurin mutation or inhibition confers a yeast-locked phenotype indicating that calcineurin governs the dimorphic transition. Genetic analysis in this study reveals that two calcineurin A catalytic subunits (out of three) are functionally diverged. Homology modeling illustrates modes of resistance resulting from amino substitutions in the interface between each calcineurin subunit and the inhibitory drugs. In addition, we show how the dimorphic transition orchestrated by calcineurin programs different outcomes during host-pathogen interactions. For example, when macrophages phagocytose Mucor yeast, subsequent phagosomal maturation occurs, indicating host cells respond appropriately to control the pathogen. On the other hand, upon phagocytosis of spores, macrophages fail to form mature phagosomes. Cytokine production from immune cells differs following exposure to yeast versus spores (which germinate into hyphae). Thus, the morphogenic transition can be targeted as an efficient treatment option against Mucor infection. In addition, genetic analysis (including gene disruption and mutational studies) further strengthens the understanding of calcineurin and provides a foundation to develop antifungal agents targeting calcineurin to deploy against Mucor and other pathogenic fungi.

Human Fungal Pathogens of Mucorales and Entomophthorales

In recent years, we have seen an increase in the number of immunocompromised cohorts as a result of infections and/or medical conditions, which has resulted in an increased incidence of fungal infections. Although rare, the incidence of infections caused by fungi belonging to basal fungal lineages is also continuously increasing. Basal fungal lineages diverged at an early point during the evolution of the fungal lineage, in which, in a simplified four-phylum fungal kingdom, Zygomycota and Chytridiomycota belong to the basal fungi, distinguishing them from Ascomycota and Basidiomycota. Currently there are no known human infections caused by fungi in Chytridiomycota; only Zygomycotan fungi are known to infect humans. Hence, infections caused by zygomycetes have been called zygomycosis, and the term "zygomycosis" is often used as a synonym for "mucormycosis." In the four-phylum fungal kingdom system, Zygomycota is classified mainly based on morphology, including the ability to form coenocytic (aseptated) hyphae and zygospores (sexual spores). In the Zygomycota, there are 10 known orders, two of which, the Mucorales and Entomophthorales, contain species that can infect humans, and the infection has historically been known as zygomycosis. However, recent multilocus sequence typing analyses (the fungal tree of life [AFTOL] project) revealed that the Zygomycota forms not a monophyletic clade but instead a polyphyletic clade, whereas Ascomycota and Basidiomycota are monophyletic. Thus, the term "zygomycosis" needed to be further specified, resulting in the terms "mucormycosis" and "entomophthoramycosis." This review covers these two different types of fungal infections.

Update on mucormycosis pathogenesis

PURPOSE OF REVIEW

Mucormycosis is an increasingly common fungal infection with unacceptably high mortality. The recent sequencing genome projects of Mucorales and the development of gene manipulation have enabled significant advances in understanding the pathogenesis of mucormycosis. Therefore, we review the pathogenesis of mucormycosis and highlight potential development of novel diagnostic and therapeutic modalities against this lethal disease.

RECENT FINDINGS

Much of the work has been focused on the role of iron uptake in the virulence of Mucorales. Additionally, host receptors and fungal ligands involved in the process of tissue invasion as well as sporangiospore size and sex loci and their contribution to virulence of Mucorales are discussed. Finally, the role of innate and adaptive immunity in protection against Mucorales and new evidence about drug-induced apoptosis in these fungi are discussed.

SUMMARY

Recent discoveries introduce several potentially novel diagnostic and therapeutic modalities, which are likely to improve management and outcome for mucormycosis. Future preclinical and clinical research is warranted to develop these diagnostic and therapeutic strategies.

Neutropenia and invasive fungal infection in patients with hematological malignancies treated with chemotherapy: a multicenter, prospective, non-interventional study in China

In this study, we explored the relationship between neutropenia (absolute neutrophil count (ANC) <1,500/mm(3)) and invasive fungal infection (IFI) in Chinese patients who had hematological malignancies treated with chemotherapy. We conducted a multicenter, prospective, non-interventional study of consecutive patients with hematological malignancies undergoing chemotherapy in China and determined clinical characteristics of patients who developed neutropenia and IFI. The results indicated that for the 2,177 neutropenic patients, 88 (4.0 %) were diagnosed with IFI. We found that a high risk of IFI (P<0.05) is associated with male gender, non-remission of the primary disease, use of two or more broad-spectrum antibiotics, treatment with parenteral nutrition, presence of cardiovascular disease, history of IFI, and neutropenia. When the ANC was less than 1,000, 1,000∼500, 500∼100, and <100/mm(3), the incidence of IFI was 0.5, 5.2, 3.9, and 4.7 %, respectively (ANC>1,000/mm(3) versus other groups, P<0.001). When the ANC was less than 1,000, 500, or 100/mm(3) for 10 days or more, the incidence of IFI was 3.2 versus 6.1 % (P=0.0052), 3.5 versus 7.1 % (P=0.0021), and 3.1 versus 10.0 % (P<0.001). When the ANC was less than 100/mm(3), taking antifungal prophylaxis reduced the incidence of IFI (P<0.05). The IFI-attributable mortality rate was 11.7 %. In conclusion, Chinese patients with IFI, severe and prolonged neutropenia increases the incidence of IFI. The incidence of IFI associated with neutropenia was reduced when antifungal prophylaxis was given. IFI was associated with a significantly increased high mortality rate in hematological malignancy patients with neutropenia.

Predisposing Factors for Mucormycosis in Patients with Diabetes Mellitus; An Experience of 21 Years in Southern Iran

OBJECTIVES

To determine the prevalence and predisposing factors of mucormycosis in patients with diabetes mellitus (DM) in a Shiraz referral centers.

METHODS

This retrospective case control study, reviewed the medical records of 162 patients with pathologically confirmed diagnosis of mucormycosis hospitalized in two major Shiraz University hospitals during the last 21 years. For each diabetic patient, two patients with diabetic ketoacidosis (DKA) matched for age, sex and the date of admission was selected as control group. Age, type of diabetes mellitus (DM) and duration of involvement as well as paraclinical findings were compared between cases and controls.

RESULTS

There were 162 patients with murormycosis of which 30 (18.5%) had DM as predisposing factor. Diabetes was the second common predisposing disease next to leukemia. There were 19 (63.3%) women and 11 (36.7%) men among the patients. The overall mortality rate was 53.33% mortality rate. The mean age of the patients was 45.3 ± 17.6 years. The mean duration of diabetes in case and control groups were 5.75 ± 5.43 and 7.2 ± 7.85 years respectively, without any statistical significance between them (p=0.063). Blood sugar in patients was lower than control group (p=0.012). Serum bicarbonate level in case group was higher than in control group (p<0.001). Arterial pH in control group was more acidic than case group (p<0.001). Insulin dependent DM was significantly more prevalent in control group compared to case group (73.4% vs. 36.6%; p=0.002).

CONCLUSION

Our study showed that the number of hospitalized patients with mucormycosis over the last 7 years has been decreased which is due to better control of infection in diabetics. In addition to hyperglycemia and acidosis, several other unknown factors like immune defects may predispose diabetics to this fungal infection.

Successful management of cutaneous mucormycosis by delaying debridement

Mucormycosis is a frightening medical condition which has baffled clinicians all over the world. Cutaneous mucormycosis is, in particular, extremely invasive, leading to high rates of morbidity and mortality. Timely intervention with antifungal drug Amphotericin B and early radical debridement are keys for favorable outcome.Three consecutive patients died of cutaneous mucormycosis despite being treated with Amphotericin B and an early extensive debridement. With disappointing results in these patients, the treatment protocol was changed. Instead of early aggressive surgical intervention, the debridement was withheld for minimum 10 days or more, until Amphotericin B started to show its effect. Debridement was carried out conservatively after 10 days. The resultant raw area was covered with the split-thickness skin graft later.The concept of "Delay the Debridement" was efficacious in the successive 5 patients with minimum morbidity and less reconstructive requirements. Our study contradicts the popular wisdom of the necessity of early vigorous debridement. We think that the timing of debridement is one of the most important determinants of mortality.The scientific reasons for delaying the debridement have been discussed. This appears to be the first report of successful management of cutaneous mucormycosis by delaying the debridement.

Pathogenesis of mucormycosis

Mucormycosis is a life-threatening infection that occurs in patients who are immunocompromised because of diabetic ketoacidosis, neutropenia, organ transplantation, and/or increased serum levels of available iron. Because of the increasing prevalence of diabetes mellitus, cancer, and organ transplantation, the number of patients at risk for this deadly infection is increasing. Despite aggressive therapy, which includes disfiguring surgical debridement and frequently adjunctive toxic antifungal therapy, the overall mortality rate is high. New strategies to prevent and treat mucormycosis are urgently needed. Understanding the pathogenesis of mucormycosis and the host response to invading hyphae ultimately will provide targets for novel therapeutic interventions. In this supplement, we review the current knowledge about the virulence traits used by the most common etiologic agent of mucormycosis, Rhizopus oryzae. Because patients with elevated serum levels of available iron are uniquely susceptible to mucormycosis and these infections are highly angioinvasive, emphasis is placed on the ability of the organism to acquire iron from the host and on its interactions with endothelial cells lining blood vessels. Several promising therapeutic strategies in preclinical stages are identified.

Characterization of the cellular immune responses to Rhizopus oryzae with potential impact on immunotherapeutic strategies in hematopoietic stem cell transplantation

Infections due to mucormycetes have a poor outcome, in particular in allogeneic hematopoietic stem cell transplantation (HSCT). In order to evaluate the cellular host response against mucormycetes, we enriched and cultivated anti-Rhizopus oryzae T cells from healthy individuals. These cells were characterized as memory/effector T(H)1 cells, they proliferated upon restimulation, they exhibited cross-reactivity to some but not all Mucorales species tested, and they increased the activity of phagocytes. Compared with the original cell fraction, the generated cells exhibited significant lower alloreactivity. Our data may form the basis for further investigations, which may ultimately lead to adoptive immunotherapeutic strategies for allogeneic HSCT recipients suffering from mucormycosis.

Host cell invasion in mucormycosis: role of iron

Clinical hallmarks of mucormycosis infections include the unique susceptibility of patients with increased available serum iron, the propensity of the organism to invade blood vessels, and defective phagocytic function. These hallmarks underscore the crucial roles of iron metabolism, phagocyte function, and interactions with endothelial cells lining blood vessels, in the organism's virulence strategy. In an attempt to understand how Mucorales invade the host, we will review the current knowledge about interactions between Mucorales and the host while evading phagocyte-mediated killing. Additionally, since iron is an important determinant of the disease, we will focus on the role of iron on these interactions. Ultimately, a superior understanding of the pathogenesis of mucormycosis will enable development of novel therapies for this disease.

Molds: hyalohyphomycosis, phaeohyphomycosis, and zygomycosis

Emerging fungi previously thought to be nonpathogenic are now recognized as playing a significant role in the increased incidence of invasive fungal disease. This change in the epidemiology of invasive fungal infections (IFIs) has occurred in the era of aggressive new therapies for hematopoietic stem cell transplantation and other malignancies that lead to profound immunosuppression for longer durations and has extended the survival of these critically ill patients. The significant morbidity and mortality associated with these infections is not only related to the host populations but to delayed recognition and diagnosis and high rates of resistance in some of these emerging pathogens to standard antifungal therapies.

Hard palate perforation in acute lymphoblastic leukemia due to mucormycosis - a case report

Palatal perforation can occur due to trauma, infection and malignancy. Mucormycosis is a rare opportunistic fungal infection caused by an organism of class zygomycetes. Rhinocerebral mucormycosis is the most common type of mucormycosis that typically starts in maxillary antrum in immunocompromised patients. Invasion of surrounding structures leads to necrotizing ulcer of the hard palate and ultimately leads to perforation. Here, we report a case of perforation of the hard palate due to mucormycosis in a eight years child having acute lymphoblastic leukemia (ALL), who was on prolonged chemotherapy and corticosteroid therapy. This case is being reported for its rarity. The aim of presenting this case report is to emphasize that the infection due to mucomycosis should be included in the differential diagnosis of hard palate perforation in ALL patients who are immunocompromised.

Novel perspectives on mucormycosis: pathophysiology, presentation, and management

Mucormycosis is a life-threatening fungal infection that occurs in immunocompromised patients. These infections are becoming increasingly common, yet survival remains very poor. A greater understanding of the pathogenesis of the disease may lead to future therapies. For example, it is now clear that iron metabolism plays a central role in regulating mucormycosis infections and that deferoxamine predisposes patients to mucormycosis by inappropriately supplying the fungus with iron. These findings raise the possibility that iron chelator therapy may be useful to treat the infection as long as the chelator does not inappropriately supply the fungus with iron. Recent data support the concept that high-dose liposomal amphotericin is the preferred monotherapy for mucormycosis. However, several novel therapeutic strategies are available. These options include combination therapy using lipid-based amphotericin with an echinocandin or with an azole (largely itraconazole or posaconazole) or with all three. The underlying principles of therapy for this disease remain rapid diagnosis, reversal of underlying predisposition, and urgent surgical debridement.

Immunological aspects of fungal pathogenesis

The incidence of infection with the pathogenic fungi continues to escalate, especially in the era of the acquired immune deficiency syndrome. To the clinician, this heterogeneous group of organisms poses both a diagnostic and a therapeutic challenge. Consequently, growing numbers of investigators are seeking to elucidate the pathogenetic mechanisms involved in disease caused by medically important fungi. In this review, many of the recent scientific advances that have been made in the immunological aspects of the pathogenesis of fungal infections are presented. The topics covered include 1) the receptors for fungi on the surface of professional phagocytes; 2) the mechanisms for killing and growth inhibition of fungi by phagocytes; 3) the means by which fungi evade host defenses; 4) the role of humoral immunity in fungal infection; 5) immunoregulation in fungal infections; and 6) the influence of cytokines on host defenses against pathogenic fungi.

Experimental basis for the clinical epidemiology of fungal infections. A review

Based on the concept that the agents of deep fungal infections can be divided into primary pathogens and opportunists the experimental basis for the clinical epidemiology of mycoses is outlined. Kinetics of experimental infections with opportunists and primary pathogens discriminate between the two fungal categories. Natural resistance eliminates opportunists and prevents the establishment of progressive infection in the normal host. Primary pathogens call upon mechanisms of adoptive cell mediated immunity for their control. Therefore athymic mice which are not more susceptible to opportunists than control mice, cannot control infection with primary pathogens. In order to induce comparable overwhelming opportunistic mycoses with reasonable challenge doses, non-specific phagocytic resistance has to be eliminated. In agreement with in vivo studies, in vitro studies of the susceptibility of fungi to killing by phagocytes point out, that the susceptibility of the tissue phase of fungi to killing by "immunologically unarmed" phagocytes discriminates between opportunists and primary pathogens. In order to restrain primary pathogenic fungi, phagocytes have also in vitro to call upon adoptive, T cell-dependent immune mechanisms, which appear superfluous for control of opportunists. This difference explains the discrepant opportunistic proclivities of the two fungal categories. Patients with defective phagocytic defenses are prone to opportunistic mycoses, while deficient cell mediated immunity results in a greater vulnerability to primary pathogens.

Host-parasite interaction in fungal infections

The outcome of host-parasite interactions in fungal infections is determined by the balance between pathogenicity of the organism and the adequacy of the host defenses. A wide variety of host defense mechanisms are involved in protection against fungal infections. These include nonspecific mechanisms such as intact skin and mucus membranes, indigenous microbial flora, and the fungicidal activity of neutrophils and monocytes. Such mechanisms constitute the major host defense against opportunistic fungal infections caused by ubiquitous organisms of low virulence. The effective role of immunoglobulins and complement as opsonins varies with the fungal pathogen involved. Specific immune responses of both the humoral and cell-mediated type develop in response to infections by pathogenic fungi. Antibodies, in general, are not of major importance in protection against these infections. Specifically sensitized T lymphocytes produce lymphokines that activate macrophages. Activated macrophages are the major line of defense against systemic fungal pathogens. The type and degree of impairment in immune responses determines the susceptibility and severity of diseases. The type of immune response also determines the tissue reactions in these diseases and sometimes may be involved in the pathogenesis of the disease process. The role of natural killer cell activity, antibody-dependent cellular cytotoxicity, and biological response modifiers in various fungal infections has been described recently. The microbial factors of importance in fungal infections are adherence, invasion, presence of an antiphagocytic capsule, and ability to grow under altered physiological states of the host. The differences in the virulence of fungal strains is of minor importance in determining the outcome in general. The seriousness of the alteration of the host state rather than the pathogenic properties of the fungus determine the severity of the disease.

In vitro susceptibility of fungi to killing by neutrophil granulocytes discriminates between primary pathogenicity and opportunism

Pathogenic fungi, according to their propensity to cause infection of apparently normal individuals, can be grouped into either primary pathogens (e.g., Coccidioides, Histoplasma, Paracoccidioides, Blastomyces, and Sporothrix) or opportunists (e.g., Candida, Mucoraceae, Aspergillus spp., Petriellidium, and Trichosporon). There is, however, no unifying concept explaining the difference between the virulence of the two fungal categories. Previously we have speculated that neutrophils are the common denominator of the high natural resistance to opportunistic fungi. Accordingly, we then compared the susceptibility to killing by neutrophil granulocytes of Histoplasma, Blastomyces, Paracoccidioides, and Sporothrix with that of 14 opportunistic fungi. We found the four virulent dimorphic yeasts, in contrast to opportunistic fungi, to be resistant to killing by neutrophils. Virulent dimorphic yeasts were ingested by neutrophils, and triggered a respiratory burst comparably to opportunists but were less susceptible to hydrogen peroxide, suggesting that differences in the susceptibility to microbicidal products of leukocytes may explain the difference in virulence.

Host-parasite relationship in opportunistic mycoses

Aspergillosis and mucormycosis are opportunistic fungal infections that share several unique features. The etiologic agents of aspergillosis and mucormycosis are ubiquitous in the environment, but are opportunistic organisms and usually infect only patients predisposed by some underlying disease or treatment. These infections are typically characterized by hyphal tissue invasion and a predilection of the organism for blood vessel invasion with hemorrhage, necrosis, and infarction. Also, these organisms are not dimorphic, like the true pathogenic dimorphic fungi, as they grow both in the environment and within the host in hyphal forms. However, the host must contend with several forms to successfully eliminate them. Each form displays different antigenic and surface features and elicits different host responses. Finally, if germination and hyphal growth occur, the host must compete with a rapidly growing organism that is too large to be ingested by a single cell and so must be handled by extracellular defense mechanisms.

Immunology of fungal infections in animals

The nature of immunity to fungal infection is discussed predominantly for mammals and birds. T-cell-mediated immunity seems essential for recovery both from cutaneous and mucosal infections (Candida, Malassezia and dermatophytes) and from infections of systemic fungal pathogens (Cryptococcus, Blastomyces, Histoplasma, and Coccidioides). Often chronic progressive disease caused by these fungi is associated with a depression or absence of T-cell-mediated immunity to antigens of the infecting fungus. In contrast recovery from disease, or absence of clinical disease after exposure to these fungi, is associated with the presence of strong T-cell-mediated immune responses to the fungus. The activation of macrophages and the stimulation of epidermal growth and keratinization are the processes induced by T-cell-mediated immunity which result in the resolution of systemic or cutaneous and mucosal disease. Other cell types, for example NK cells and PMNs (polymorphonuclear leucocytes), may be important in these diseases in reducing the effective amount of inoculum to which an animal is exposed and thereby reducing the likelihood of disseminated disease. Invasive opportunistic fungi (Candida, Aspergillus, Mucorales) are resisted by PMNs which attach to the hyphae or pseudohyphae and damage them via an extracellular mechanism. Other host cell types may be important in natural resistance, fungal spores being handled by the macrophages which, under conditions when animals are not immunosuppressed, are likely to be an effective first line of defense. Subcutaneous pathogens and miscellaneous other fungal diseases are discussed from a point of view of host immunity and immunodiagnosis. Vaccine development for ringworm and for other mycoses is discussed.

Neutrophil chemotactic responses induced by fresh and swollen Rhizopus oryzae spores and Aspergillus fumigatus conidia

With the induction of germination, Rhizopus oryzae spores and Aspergillus fumigatus conidia activate the complement system and induce neutrophil chemotaxis. In contrast, freshly isolated R. oryzae spores did not induce neutrophil migration into lung tissue of mice after intranasal inoculation. Moreover, in microchemotaxis assays neither fresh R. oryzae spores nor A. fumigatus conidia activated sera to stimulate human neutrophil chemotaxis above control migration until at least 10(7) or 10(8) spores or conidia per ml of sera were used. The increased generation of chemotactic factors by swollen spores and conidia was not due to an increased surface area, as there was decreased neutrophil chemotactic response to Rhizopus or Aspergillus hyphae when compared with swollen spores or conidia.

Specific susceptibility to mucormycosis in murine diabetes and bronchoalveolar macrophage defense against Rhizopus

To assess the influence of diabetes mellitus in predisposing to pulmonary mucormycosis, a murine model of streptozotocin-induced diabetes was used. Intranasal inoculation of Rhizopus oryzae into diabetic mice resulted in mucormycotic infection with histopathology resembling pulmonary mucormycosis observed in humans. There was no mortality nor infection in inoculated normal mice. Diabetic mice had fatal infections caused by R. oryzae but significantly reduced mortality following inoculation with Aspergillus fumigatus. These findings reflect the specific enhanced susceptibility to mucormycosis observed in human diabetics. Normal bronchoalveolar macrophages formed part of an efficient defense against R. oryzae by inhibiting germination, the critical step in the conversion of R. oryzae to its tissue invasive phase. Bronchoalveolar macrophages inhibited spore germination in vitro and appeared to help prevent germination in vivo. In contrast, spore germination occurred in diabetic mice following intranasal inoculation. Diabetic bronchoalveolar macrophages had a decreased ability to attach to hyphae. In diabetic mice, bronchoalveolar macrophages could damage spores or hyphae of R. oryzae, but serum factors appeared to both promote spore germination and impair attachment of macrophages to spores. This murine model of diabetes mellitus provides an opportunity for evaluation of the relative importance of cell and serum-mediated host factors in the pathogenesis of mucormycosis.