Identification of mucorales from clinical specimens: a 4-year experience in a single institution

Targeted PCR of Mucorales in pediatric bronchoalveolar lavage samples indicates low prevalence of airway colonization and sample contamination

Mucorales are a large order of ubiquitous saprophytic zygomycete fungi and act as opportunistic pathogens in humans. In pediatric patients, little is known about the role of Mucorales in airway colonization and infection or their role as contaminants of respiratory samples. Currently, polymerase chain reaction (PCR) is the most sensitive mode of detection Mucorales in clinical specimen. In this study, we aimed to determine the prevalence of Mucorales in bronchoalveolar lavage samples (BAL) from a large, diverse group of pediatric patients. We performed commercial Mucorales PCR (MucorGenius®, Pathonostics, Maastricht, NL, USA) on 102 thawed BAL samples of 100 patients. Mucorales PCR was negative in all samples. Our data suggest that Mucorales spp. have a low prevalence in paediatric airways and do not frequently contaminate pediatric BAL samples.

Syncephalastrum massiliense sp. nov. and Syncephalastrum timoneanum sp. nov. Isolated from Clinical Samples

Mucormycosis is known to be a rare opportunistic infection caused by fungal organisms belonging to the Mucorales order, which includes the Syncephalastrum species. These moulds are rarely involved in clinical diseases and are generally seen as contaminants in clinical laboratories. However, in recent years, case reports of human infections due to Syncephalastrum have increased, especially in immunocompromised hosts. In this study, we described two new Syncephalastrum species, which were isolated from human nails and sputum samples from two different patients. We used several methods for genomic and phenotypic characterisation. The phenotypic analysis relied on the morphological features, analysed both by optical and scanning electron microscopy. We used matrix-assisted laser desorption-ionization time-of-flight mass spectrometry, energy-dispersive X-ray spectroscopy, and BiologTM technology to characterise the proteomic, chemical mapping, and carbon source assimilation profiles, respectively. The genomic analysis relied on a multilocus DNA sequence analysis of the rRNA internal transcribed spacers and D1/D2 large subunit domains, fragments of the translation elongation factor-1 alpha, and the β-tubulin genes. The two novel species in the genus Syncephalastrum, namely S. massiliense PMMF0073 and S. timoneanum PMMF0107, presented a similar morphology: irregular branched and aseptate hyphae with ribbon-like aspects and terminal vesicles at the apices all surrounded by cylindrical merosporangia. However, each species displayed distinct phenotypic and genotypic features. For example, S. timoneanum PMMF0107 was able to assimilate more carbon sources than S. massiliense PMMF0073, such as adonitol, α-methyl-D-glucoside, trehalose, turanose, succinic acid mono-methyl ester, and alaninamide. The polyphasic approach, combining the results of complementary phenotypic and genomic assays, was instrumental for describing and characterising these two new Syncephalastrum species.

Rapid detection of Mucorales based on recombinase polymerase amplification and real-time PCR

Mucormycosis, an invasive fungal disease with severe consequences, poses a significant threat to immunocompromised individuals. However, the timely and accurate identification of Mucorales infection continues to present difficulties. In this study, novel detection techniques utilizing recombinase polymerase amplification (RPA) and quantitative real-time polymerase chain reaction (qPCR) were developed, specifically targeting the mitochondrial rnl gene, in order to address this challenge. The specificity of the RPA and qPCR assay was assessed by adding genomic DNAs extracted from 14 non-targeted strains, as well as human and mouse blood. No false-positive results were observed. Additionally, genomic DNAs from 13 species in five genera of order Mucorales were tested and yielded positive results in both methods. To further evaluate the sensitivity of the assays, DNAs from Rhizopus oryzae, Mucor racemosus, Absidia glauca, Rhizomucor miehei, and Cunninghamella bertholletiae were utilized, with concentrations ranging from 1 ng/μL to 1 fg/μL. The limit of detection (LoD) for the RPA assay was determined to be 1 pg., with the exception of Rhizomucor miehei which had a LoD of 1 ng. The LoD for the qPCR assay varied between 10 fg and 1 pg., depending on the specific species being tested. Sensitivity analysis conducted on simulated clinical samples revealed that the LoD for RPA and qPCR assays were capable of detecting DNA extracted from 103 and 101 colony forming units (CFU) conidia in 200 μL of blood and serum, respectively. Consequently, the real-time RPA and qPCR assays developed in this study exhibited favorable sensitivity and specificity for the diagnosis of mucormycosis.

Isolated cerebral mucormycosis that looks like stroke and brain abscess: A case report and review of the literature

BACKGROUND

Cerebral mucormycosis is an infectious disease of the brain caused by fungi of the order Mucorales. These infections are rarely encountered in clinical practice and are often misdiagnosed as cerebral infarction or brain abscess. Increased mortality due to cerebral mucormycosis is closely related to delayed diagnosis and treatment, both of which present unique challenges for clinicians.

CASE SUMMARY

Cerebral mucormycosis is generally secondary to sinus disease or other disseminated disease. However, in this retrospective study, we report and analyze a case of isolated cerebral mucormycosis.

CONCLUSION

The constellation of symptoms including headaches, fever, hemiplegia, and changes in mental status taken together with clinical findings of cerebral infarction and brain abscess should raise the possibility of a brain fungal infection. Early diagnosis and prompt initiation of antifungal therapy along with surgery can improve patient survival.

Mucormycosis threats: A systemic review

During the catastrophic wave of Coronavirus disease 2019, health agencies started to report an infrequent but lethal mucormycosis or black fungal infection. Primarily, it causes sinusitis by affecting nasal, oral, lung, brain, ocular, and other body tissues. It becomes more fatal, especially in diabetic, cancer, and immune-compromised patients. Before 2020, the prevalence of mucormycosis was very rare but it has rapidly emerged globally from late 2020 to mid-2021. Recently, the mucormycosis got worse and epidemic with more than 30,000 cases reported across India. The etiology of infection can be diagnosed by molecular, serological, microscopic, and clinical methods. However, early diagnosis of this ailment is still a challenging task due to no standalone diagnostic tool available along with clinical manifestations of the ailment resembling other fungal diseases. The treatment of mucormycosis is also challenging and frequently requires long-term treatment. Amphotericin B was found to be an effective antifungal for preventing mucormycosis but it failed if infection disseminated to necrotizing tissues or adjacent organs. Removal of infected tissue/organ by surgery is an alternative treatment to control mucormycosis. In addition, reversal of underlying predisposing conditions based on therapy is also in practice for its prevention. This review highlights different aspects of mucormycosis such as pathogenesis, diagnosis, treatment, and their challenges and so on. We also emphasized the epidemiological shift during the recent outbreak and its influence on the different regions of India.

Mucormycosis co-infection in COVID-19 patients: An update

Mucormycosis (MCM) is a rare fungal disorder that has recently been increased in parallel with novel COVID-19 infection. MCM with COVID-19 is extremely lethal, particularly in immunocompromised individuals. The collection of available scientific information helps in the management of this co-infection, but still, the main question on COVID-19, whether it is occasional, participatory, concurrent, or coincidental needs to be addressed. Several case reports of these co-infections have been explained as causal associations, but the direct contribution in immunocompromised individuals remains to be explored completely. This review aims to provide an update that serves as a guide for the diagnosis and treatment of MCM patients' co-infection with COVID-19. The initial report has suggested that COVID-19 patients might be susceptible to developing invasive fungal infections by different species, including MCM as a co-infection. In spite of this, co-infection has been explored only in severe cases with common triangles: diabetes, diabetes ketoacidosis, and corticosteroids. Pathogenic mechanisms in the aggressiveness of MCM infection involves the reduction of phagocytic activity, attainable quantities of ferritin attributed with transferrin in diabetic ketoacidosis, and fungal heme oxygenase, which enhances iron absorption for its metabolism. Therefore, severe COVID-19 cases are associated with increased risk factors of invasive fungal co-infections. In addition, COVID-19 infection leads to reduction in cluster of differentiation, especially CD4+ and CD8+ T cell counts, which may be highly implicated in fungal co-infections. Thus, the progress in MCM management is dependent on a different strategy, including reduction or stopping of implicit predisposing factors, early intake of active antifungal drugs at appropriate doses, and complete elimination via surgical debridement of infected tissues.

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.

Storm of a rare opportunistic life threatening mucormycosis among post COVID-19 patients: A tale of two pathogens

Mucormycosis is a rare but life-threatening opportunistic fungal infection caused by a group of molds that belong to Zygomycetes of the order Mucorales. These fungi are found in the environment such as soil, decaying vegetation, and organic matters. Sporangiospores present in the environment enter the human body through inhalation or direct skin inoculation by trauma or ingestion and result in pulmonary, cutaneous, and gastrointestinal mucormycosis, respectively, in immunocompromised hosts. Patients with uncontrolled diabetes, hematological malignancies, high-dose glucocorticoid therapy, iron overload, and organ transplantation are at high risk of acquiring mucormycosis. The second wave of severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] affected India severely with the highest number of cases and deaths compared to all other countries. Additionally, the country was affected by emergence of rare but life-threatening mucormycosis. Currently, many coronavirus disease 2019 patients with underlying risk factors such as uncontrolled diabetes, high-dose steroid therapy, and exposure to mechanical ventilation have developed mucormycosis. Inhalation is the most common mode of transmission that results in colonization of sporangiospores in the nose. In immunocompromised host, sporangiospores germinate, and subsequently form hyphae. These hyphae invade into tissues, and produce tissue infarction, necrosis, and thrombosis. Angioinvasion causes hematogenous dissemination to many organs, predominantly to brain, that result in rhino-orbital-cerebral mucormycosis. Clinical characteristics, radio imaging, fungal culture, histopathology, and molecular techniques are the key diagnostic methods. Surgical intervention and aggressive antifungal therapy are the main management strategies. Amphotericin B is the drug of choice for treatment of mucormycosis, whereas posaconazole or isavuconazole is used for step-down therapy and salvage therapy.

Dental and Oral Manifestations of COVID-19 Related Mucormycosis: Diagnoses, Management Strategies and Outcomes

It has been nearly two years since the pandemic caused by the novel coronavirus disease (COVID-19) has affected the world. Several innovations and discoveries related to COVID-19 are surfacing every day and new problems associated with the COVID-19 virus are also coming to light. A similar situation is with the emergence of deep invasive fungal infections associated with severe acute respiratory syndrome 2 (SARS-CoV-2). Recent literature reported the cases of pulmonary and rhino-cerebral fungal infections appearing in patients previously infected by COVID-19. Histopathological analysis of these cases has shown that most of such infections are diagnosed as mucormycosis or aspergillosis. Rhino-orbital-cerebral mucormycosis usually affects the maxillary sinus with involvement of maxillary teeth, orbits, and ethmoidal sinuses. Diabetes mellitus is an independent risk factor for both COVID-19 as well as mucormycosis. At this point, there is scanty data on the subject and most of the published literature comprises of either case reports or case series with no long-term data available. The aim of this review paper is to present the characteristics of COVID-19 related mucormycosis and associated clinical features, outcome, diagnostic and management strategies. A prompt diagnosis and aggressive treatment planning can surely benefit these patients.

Isolated cerebral mucormycosis masquerading as a tumor in an immunocompetent patient

Mucormycosis is an opportunistic fungal disease that commonly presents as cutaneous or rhinocerebral infections associated with immunocompromised states. It may exceptionally present as isolated involvement of the brain with a varied clinical presentation, which may be difficult to diagnose early, leading to increased mortality. Herein, we report the case of a 42-year-old immunocompetent female with left-sided limb weakness and a history of recurrent vomiting and headache for the last two years. Clinically, glioma was suspected, but histopathological examination revealed a few broad aseptate fungal hyphae. As no other organ was involved, the diagnosis of isolated cerebral mucormycosis was rendered. Reporting this case, we show an unusual presentation of a central nervous system mucormycosis masquerading a tumor in an immunocompetent patient. The case also highlights the importance of a careful histopathological examination to avoid missing the presence of occasional fungal hyphae. Ideally, recognition of fungal hyphae in the brain, during intraoperative consultation, can prompt brain tissue culture for definitive diagnosis and early empirical antifungal therapy, which may prove life-saving.

Clinical Usefulness of Fungal Culture of EBUS-TBNA Needle Rinse Fluid and Core Tissue

PURPOSE

The diagnosis of pulmonary fungal infections is challenging due to the difficulty of obtaining sufficient specimens. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) needle rinse fluid has become an emerging diagnostic material. This study evaluated the role of routine fungal culture from EBUS-TBNA needle rinse fluid, in addition to histopathologic examination and fungal culture of EBUS-TBNA core tissue, in the diagnosis of pulmonary fungal infections.

MATERIALS AND METHODS

Among patients who underwent EBUS-TBNA, those with results for at least one of three tests (histopathologic examination, fungal culture of EBUS-TBNA core tissue or needle rinse fluid) were included. Patients with a positive test were divided into two groups (clinical fungal infection and suspected fungal contamination) according to their clinical assessment and therapeutic response to antifungal.

RESULTS

Of 6072 patients, 41 (0.7%) had positive fungal tests and 9 (22%) were diagnosed as clinical fungal infection. Of the 5222 patients who were evaluated using a fungal culture from EBUS-TBNA needle rinse fluid, 35 (0.7%) had positive results. However, only 4 out of 35 (11.4%) were classified as clinical fungal infection. Positive results were determined in 4 of the 68 (5.9%) evaluated by a fungal culture of EBUS-TBNA core tissue, and all were diagnosed as clinical fungal infection.

CONCLUSION

Routine fungal culture of EBUS-TBNA needle rinse fluid is not useful due to the low incidence of fungal infection and high rate of contamination. However, fungal culture of EBUS-TBNA core tissue and needle rinse fluid should be considered in patients with clinically suspected fungal infection.

Fatal and Rapid Progressive Isolated Cerebral Mucormycosis Involving the Bilateral Basal Ganglia: A Case Report

Isolated cerebral mucormycosis is a clinical type of mucormycosis that is estimated to account for 8% of all mucormycosis cases. The clinical symptoms of isolated cerebral mucormycosis are elusive, and thus conventional techniques often lake sensitivity and specificity. Moreover, cultures are often negative, even when direct microscopy examination is positive. Although histopathology will probably remain the gold standard for the diagnosis of mucormycosis, obtaining a biopsy specimen is not always feasible in most vulnerable populations. Thus, molecular approaches are currently used as an advantageous assistant examination method to improve the early identification of the causative agent and subsequently guide therapy to improve the prognosis of patients. Here, we report a case of isolated cerebral mucormycosis caused by Rhizopus microspores in a healthy young adult that was identified using next-generation sequencing technology.

Superficial Cutaneous Zygomycosis Presenting as Resistant Intertrigo: A Case Report

Zygomycosis is an angioinvasive fungal infection with a high mortality rate. Cutaneous zygomycosis is the second most common form of the disease, typically characterized by necrotic eschars in an immunocompromised host. We report an unusual case of superficial intertrigo resistant to conventional therapies caused by Mucor circinelloides in a patient with HIV and diabetes.

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

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

Challenges in the diagnosis and treatment of mucormycosis

The diagnosis and treatment of mucormycosis are challenging. The incidence of the disease seems to be increasing. Hematological malignancies are the most common underlying disease in countries with high income and uncontrolled diabetes in developing countries. Clinical approach to diagnosis lacks sensitivity and specificity. Radiologically, multiple (≥10) nodules and pleural effusion are reportedly associated with pulmonary mucormycosis. Another finding on computerized tomography (CT) scan, which seems to indicate the presence of mucormycosis, is the reverse halo sign. Microscopy (direct and on histopathology) and culture are the cornerstones of diagnosis. Molecular assays can be used either for detection or identification of mucormycetes, and they can be recommended as valuable add-on tools that complement conventional diagnostic procedures. Successful management of mucormycosis is based on a multimodal approach, including reversal or discontinuation of underlying predisposing factors, early administration of active antifungal agents at optimal doses, complete removal of all infected tissues, and use of various adjunctive therapies. Our armamentarium of antifungals is slightly enriched by the addition of two newer azoles (posaconazole and isavuconazole) to liposomal amphotericin B, which remains the drug of choice for the initial antifungal treatment, according to the recently published guidelines by ECIL-6, as well as those published by ECMM/ESCMID. Despite the efforts for better understanding of the pathogenesis, early diagnosis and aggressive treatment of mucormycosis, the mortality rate of the disease remains high.

Identification of Mucorales isolates from soil using morphological and molecular methods

Background and Purpose:

Soil is the main habitat of saprophytic and pathogenic fungi. Mucoromycotina constitutes a large group of soil fungi, with certain opportunistic members causing systemic infections in immunocompromised hosts. The majority of human and animal infections are caused by the members of the genera Rhizopus, Mucor, Rhizomucor, Lichtheimia (Absidia), Cunninghamella, and Mortierella. Accordingly, in the present study, we aimed to isolate and identify the main genera of the order Mucorales, using molecular assays and morphological features.

Materials and Methods:

In total, 340 soil samples were collected from seven public parks throughout the city and sidewalk gardens in 14 municipal districts in Isfahan, Iran. All the samples were cultured on the appropriate media, incubated at 27°C for 2- 4 days, and examined daily for visible fungal growth. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was applied and macroscopic, microscopic, and physiological characteristics were assessed to identify fungal colonies.

Results:

400 pure colonies, belonging to the orders Mucorales and Mortierellales, including the genera Lichtheimia, Rhizopus, Rhizomucor, Mucor, Cunninghamella, and Mortierella, were identified. The genus Rhizopus (35.5%) was the most frequent isolate, followed by Mucor (32.25%) and Rhizomucor (27.5%).

Conclusion:

The results emphasize the importance of opportunistic fungi in public areas and indicate the risk of exposure for immunocompromised individuals.