Affinity of Mucormycosis for Basal Ganglia in Intravenous Drug Users: Case Illustration and Review of Literature

Experimental Models to Study the Pathogenesis and Treatment of Mucormycosis

Mucormycosis presents a formidable challenge to clinicians and researchers. Animal models are an essential part of the effort to decipher the pathogenesis of mucormycosis and to develop novel pharmacotherapeutics against it. Diverse model systems have been established, using a range of animal hosts, immune and metabolic perturbations, and infection routes. An understanding of the characteristics, strengths, and drawbacks of these models is needed to optimize their use for specific research aims.

Social determinants of health as drivers of fungal disease

Disparities in social determinants of health (SDOH) play a significant role in causing health inequities globally. The physical environment, including housing and workplace environment, can increase the prevalence and spread of fungal infections. A number of professions are associated with increased fungal infection risk and are associated with low pay, which may be linked to crowded and sub-optimal living conditions, exposure to fungal organisms, lack of access to quality health care, and risk for fungal infection. Those involved and displaced from areas of armed conflict have an increased risk of invasive fungal infections. Lastly, a number of fungal plant pathogens already threaten food security, which will become more problematic with global climate change. Taken together, disparities in SDOH are associated with increased risk for contracting fungal infections. More emphasis needs to be placed on systematic approaches to better understand the impact and reducing the health inequities associated with these disparities.

A Case of Post-COVID-19 Rhino-Cerebral Mucormycosis in an Immunocompromised Patient

Mucormycosis is a fulminant angioinvasive fungal infection that occurs in an immunocompromised condition, most commonly in diabetic patients. Rhino-cerebral and pulmonary infections are common but may also lead to disseminated disease associated with a high mortality rate (almost 100%). Here we report on an elderly diabetic lady presented with a headache and altered level of consciousness and peri-orbital swelling following coronavirus disease 2019 (COVID-19). Imaging studies revealed a single large space-occupying lesion in the frontal lobe extending to the left orbit and sinusitis. An excisional biopsy was taken from the middle meatus of the nasal cavity and histopathology findings were broad aseptate hyphae branching at the right angle which suggests mucormycosis. Liposomal amphotericin B was started but the patient developed acute kidney injury (AKI) and bi-cytopenia (thrombocytopenia and anemia) followed by sepsis resulting in death. Though this is a rapidly progressing disease with a high mortality rate, a strong level of suspicion and early diagnosis can save lives.

Mucormycosis in COVID-19 patients: predisposing factors, prevention and management

India is considered the diabetes capital of the world and has the highest burden of mucormycosis. Bacterial, viral and fungal co-infections are increasingly being reported in severe acute respiratory syndrome virus 2 (SARSCoV-2) infected patients. India is one of the worst affected countries during the second wave of the COVID-19 pandemic. This combination of diabetes mellitus, COVID-19 and mucormycosis has led to the drastic upsurge of COVID-19-associated mucormycosis (CAM) in India. Immunosuppression, iron disequilibrium, endothelial injury, ketoacidosis and hypoxia are some of the other COVID-19-related risk factors for CAM. There has been an increase in the proportion of mucormycosis affecting paranasal sinuses and central nervous system (CNS) in CAM compared to pre-COVID-19 literature due to the SARSCoV-2-related pathophysiological mechanisms, complications and treatment strategies. CAM is a medical and surgical emergency, and it can present with non-specific symptoms and signs initially resulting in diagnostic delay. High index of suspicion and regular screening for features of CAM are of paramount importance to prevent lethal consequences. Rapid action with a tripod approach consisting of withdrawal of immunomodulators, early antifungal therapy and extensive surgical debridement is considered the best possible treatment model. We review the published data to give a detailed account of the predisposing factors and their mechanisms, diagnostic work-up, treatment modalities and prevention strategies of CAM with special emphasis on CNS mucormycosis.

Case Report: Metagenomics Next-Generation Sequencing for Diagnosing Cerebral Infarction and Infection Caused by Hematogenous Disseminated Mucormycosis in a Patient With Acute Lymphoblastic Leukemia

Disseminated mucormycosis, a serious complication, is associated with high mortality in patients with acute leukemia after chemotherapy. Blood cultures are always negative because of recurrent empirical antifungal treatments. The identification of pathogens is important for diagnosis and therapy. In this case report, we diagnosed culture-negative disseminated mucormycosis with Rhizomucor miehei infection leading to cerebral infarction in a patient with leukemia using metagenomics next-generation sequencing (mNGS) form peripheral blood, cerebral spinal fluid, and bronchoalveolar lavage fluid. mNGS technology can be applied to precisely diagnose culture-negative disseminated mucormycosis.

Isolated Cerebral Mucormycosis in Immunocompetent Adults who Inject Drugs: Case Reports and Systematic Review of the Literature

Background

Mucormycosis involves life-threatening rapidly progressive angioinvasion with infiltration across tissue planes, resulting in necrosis and thrombosis, most commonly seen in the setting of immunocompromised states. We describe 2 cases of isolated cerebral mucormycosis in immunocompetent adults and describe this syndrome in detail in the context of a systemic literature review.

Methods

Using the criteria (1) isolated cerebral disease, (2) mucormycosis (by polymerase chain reaction, culture, or pathology), and (3) affected an immunocompetent individual, we identified 53 additional cases from 1969 to 2020.

Results

Of these 55 cases, ~60% occurred in men, >70% were in patients under age 35, 92% were associated with intravenous drug use, and >85% had infection centered in the basal ganglia. Many presented with cranial nerve deficits, headache, focal weakness, or altered mental status.

Conclusions

No patient survived without amphotericin, and steroid administration was associated with worse outcomes. Given the current opioid crisis, this syndrome may be seen more frequently.

Brain lesion in a recreational drug user: Isolated cerebral mucormycosis

Isolated cerebral mucormycosis is a relatively rare and unique variant of mucormycosis which is seen most commonly in patients with intravenous recreational drug use. While this invasive fungal infection in the brain is thought to spread from the sinuses or the lungs in other hosts such as diabetics and those with malignancy, hematogenous spread and seeding has been attributed in the pathogenesis of isolated cerebral mucormycosis. Clinical features and radiological findings may be non-specific and hence, heightened clinical suspicion for a prompt diagnosis and early medical and surgical intervention is paramount for a favorable outcome in such rare, but potentially fatal infections.

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.

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.

Diagnosis of Rhinocerebral Mucormycosis by Treatment of Cavernous Right Internal Carotid Artery Occlusion With Mechanical Thrombectomy: Special Case Presentation and Literature Review

Background: Mucormycosis is a rapidly progressive, angioinvasive fungal infection that has a predilection for the paranasal sinuses and adjacent mucosa. Rhinocerebral mucormycosis (RCM) is the most common form and is known to invade the skull base and its associated blood vessels—leading to mycotic aneurysms, ischemic infarcts, and intracerebral hemorrhage. There are documented cases of mechanical thrombectomy in ischemic stroke due to RCM, however, there are no known cases that were diagnosed primarily by histological and pathological analysis of the embolus. We present a case of treatment of large vessel occlusion that led to the diagnosis and treatment of RCM.

Case Presentation: A 21 year-old male inmate with history of type 1 diabetes presented with generalized weakness, abdominal pain, right eye blindness, and ophthalmoplegia after an assault in prison. He underwent treatment for diabetic ketoacidosis, but subsequently developed left hemiplegia and was found to have complete occlusion of his right internal carotid artery. He underwent successful mechanical thrombectomy and pathological analysis of the embolus revealed a diagnosis of mucormycosis. He completed a course of amphotericin B, micafungin, and posaconazole. With the aid of acute rehabilitation he achieved a modified Rankin score of 2.

Discussion: We review the pathogenesis, diagnosis, and treatment of RCM. A comprehensive multidisciplinary approach is critical in the management of this often-fatal disease. Early diagnosis and treatment are essential in RCM as delaying treatment by more than 6 days significantly increases mortality. Treatment includes surgical debridement and intravenous antifungal therapy (amphotericin B + micafungin or caspofungin) for a minimum of 6–8 weeks.

Treatment of cerebral mucormycosis with drug therapy alone: A case report

We report on an elderly male patient with headache and right-side weakness. Imaging studies revealed multiple space-occupying lesions in the parietal and occipital cerebral regions. Biopsy revealed broad aseptate ribbon-like structures branching at right angles, suggestive of mucormycosis. Improvement was observed after medical therapy with 20 weeks of liposomal amphotericin B (5 mg/kg/day) combined with posaconazole, followed by posaconazole (400 mg twice a day) alone for 1 month. The patient recovered without neurological deficits; however, multidrug-resistant bacteraemia and hospital-acquired pneumonia occurred, resulting in death. Nevertheless, our report shows that this lethal fungal infection can sometimes show favourable progress with drug therapy alone.