Disseminated Lichtheimia ramosa Infection After Hematopoietic Stem Cell Transplantation in a Child With Chronic Granulomatous Disease

Case report: The clinical utility of metagenomic next-generation sequencing in mucormycosis diagnosis caused by fatal Lichtheimia ramosa infection in pediatric neuroblastoma

Lichtheimia ramosa (L. ramosa) is an opportunistic fungal pathogen of the order Mucorales that may result in a rare but serious mucormycosis infection. Mucormycosis could be angioinvasive, causing thrombosis and necrosis in the nose, brain, digestive tract, and respiratory tract. The infection is highly lethal, especially in immunocompromised hosts, and the incidence has been on the rise. However, due to its relatively low incidence in pediatric population and the challenges with diagnosis, the awareness and management experience for pediatric mucormycosis are extremely limited, which might lead to poor outcomes. In this study, we comprehensively reviewed the course of a fatal rhinocerebral mucormycosis case in a pediatric neuroblastoma patient receiving chemotherapy. Due to a lack of awareness of the infection, the standard care of amphotericin B treatment was delayed and not administered until the identification of L. ramosa by metagenomic next-generation sequencing (mNGS)-based pan-pathogen detection of the patient's peripheral blood sample. We also reviewed the literature on L. ramosa infection cases reported worldwide between 2010 and 2022, with an analysis of clinical manifestation, prognosis, and epidemiological data. Our study not only highlighted the clinical value of comprehensive mNGS in rapid pathogen detection but also raised awareness of recognizing lethal fungal infection early in immunocompromised hosts including pediatric cancer patients.

Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases

In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.

What Is New in Pulmonary Mucormycosis?

Mucormycosis is a rare but life-threatening fungal infection due to molds of the order Mucorales. The incidence has been increasing over recent decades. Worldwide, pulmonary mucormycosis (PM) presents in the lungs, which are the third main location for the infection after the rhino-orbito-cerebral (ROC) areas and the skin. The main risk factors for PM include hematological malignancies and solid organ transplantation, whereas ROC infections are classically favored by diabetes mellitus. The differences between the ROC and pulmonary locations are possibly explained by the activation of different mammalian receptors—GRP78 in nasal epithelial cells and integrin β1 in alveolar epithelial cells—in response to Mucorales. Alveolar macrophages and neutrophils play a key role in the host defense against Mucorales. The diagnosis of PM relies on CT scans, cultures, PCR tests, and histology. The reversed halo sign is an early, but very suggestive, sign of PM in neutropenic patients. Recently, the serum PCR test showed a very encouraging performance for the diagnosis and follow-up of mucormycosis. Liposomal amphotericin B is the drug of choice for first-line therapy, together with correction of underlying disease and surgery when feasible. After a stable or partial response, the step-down treatment includes oral isavuconazole or posaconazole delayed release tablets until a complete response is achieved. Secondary prophylaxis should be discussed when there is any risk of relapse, such as the persistence of neutropenia or the prolonged use of high-dose immunosuppressive therapy. Despite these novelties, the mortality rate from PM remains higher than 50%. Therefore, future research must define the place for combination therapy and adjunctive treatments, while the development of new treatments is necessary.

Case report: A rare case of pulmonary mucormycosis caused by Lichtheimia ramosa in pediatric acute lymphoblastic leukemia and review of Lichtheimia infections in leukemia

Mucormycosis caused by Lichtheimia ramosa is an emerging and uncommon opportunistic infection in patients with hematological malignancies, with high mortality rates. Herein, we first report a case of pulmonary mucormycosis with Lichtheimia ramosa in a 3-year-old girl recently diagnosed with B-cell acute lymphoblastic leukemia. The diagnosis was made using computerized tomography of the lung, metagenomic next-generation sequencing (mNGS) of blood and sputum specimens, and microscopic examination to detect the development of Lichtheimia ramosa on the surgical specimen. She was effectively treated after receiving prompt treatment with amphotericin B and posaconazole, followed by aggressive surgical debridement. In our case, the fungal isolates were identified as Lichtheimia ramosa using mNGS, which assisted clinicians in quickly and accurately diagnosing and initiating early intensive treatment. This case also indicated the importance of strong clinical suspicion, as well as aggressive antifungal therapy combined with surgical debridement of affected tissues.

Epidemiology and Pathophysiology of COVID-19-Associated Mucormycosis: India Versus the Rest of the World

The coronavirus disease 2019 (COVID-19) pandemic has led to a concerning resurgence of mucormycosis. More than 47,000 cases of mucormycosis were reported in three months from India. We update our systematic review on COVID-19-associated mucormycosis (CAM) till June 21st, 2021, comparing cases reported from India and elsewhere. We included individual patient details of 275 cases of CAM, of which 233 were reported from India and 42 from the rest of the world. Diabetes mellitus was the most common underlying risk factor for CAM in India than in other countries. The fatality rate of cases reported from India (36.5%) was less than the globally reported cases (61.9%), probably due to the predominance of rhino-orbital mucormycosis. On a multivariate analysis, we found that pulmonary or disseminated mucormycosis cases and admission to the intensive care unit were associated with increased mortality, while combination medical therapy improved survival. The paucity of pulmonary and disseminated mucormycosis cases from India suggests that these cases were either not diagnosed or reported, further supported by a trend of search data from the Google search engine. In this review, we discuss the factors explaining the substantial rise in cases of CAM. We also propose a hypothetical model describing the epidemiologic triad of CAM.