Mucormycoses caused by Lichtheimia species

A new terrein dimer and a new meroterpene from the mangrove endophytic fungus Lichtheimia sp

A new terrein dimer named lichtheicol A (1) and a new meroterpene named lichtheiterpene A (2), were isolated from the mangrove endophytic fungus Lichtheimia sp. J2B1, together with 10 known compounds (3-12). The planar structures and absolute configurations of 1 and 2 were established by a combination of extensive spectroscopic data analyses and electronic circular dichroism (ECD) calculations. Compounds 4 and 5 exhibited marked inhibitory effects against butyrylcholinesterase (BuChE) with IC50 values of 0.71 and 0.53 μM, respectively.

A case of COVID-19-associated mucormycosis due to Lichtheimia ramosa

BACKGROUND

Mucormycosis is a life-threatening invasive fungal infection in immunocompromised and COVID-19 patients.

CASE REPORT

Here, we report a fatal rhino-orbito-cerebral mucormycosis caused by Lichtheimia ramosa, in a 79-year-old diabetic female. She was initially admitted to the hospital for COVID-19 infection and received broad-spectrum antibiotics and corticosteroids. After 1 month, she was admitted again because of persistent headaches and decreased right eye movement when the computed tomography scan showed mucosal thickening and opacification of paranasal sinuses. Microbiological investigations, including culture and direct microscopy, and histopathological findings confirmed the diagnosis of proven mucormycosis. The isolated causal agent was identified as Lichtheimia ramosa by sequencing the entire ITS region of nuclear ribosomal DNA. Despite surgical debridement and administration of liposomal amphotericin B 5 mg/kg/day, the patient's level of consciousness suddenly deteriorated; she was intubated and mechanically ventilated in the ICU and died on the same day.

CONCLUSION

To our knowledge, this is the first worldwide case of COVID-19-associated rhino-orbito-cerebral mucormycosis due to Lichtheimia ramosa.

The application of metagenomic next-generation sequencing in patients with infection or colonization caused by Lichtheimia species

Background

Mucormycosis is considered the fourth most common invasive fungal disease after candidiasis, aspergillosis and cryptococcosis. Lichtheimia species accounted for 5%-29% of all mucormycosis. However, available data on species-specific analysis of Lichtheimia infections are limited.

Methods

This study included nine patients hospitalized in five hospitals in two cities in south China with mucormycosis or colonization caused by Lichtheimia species, diagnosed mainly by metagenomic next-generation sequencing (mNGS). The corresponding medical records were reviewed, and the clinical data analyzed included demographic characteristics, site of infection, host factors and type of underlying disease, diagnosis, clinical course, management, and prognosis.

Results

In this study, nine patients with Lichtheimia infections or colonization had a recent history of haematological malignancy (33.3%), solid organ transplants (33.3%), pulmonary disease (22.2%), and trauma (11.1%) and were categorized as 11.1% (one case) proven, 66.7% (six cases) probable mucormycosis and 22.2% (two cases) colonization. Pulmonary mucormycosis or colonization was the predominant presentation in 77.8% of cases and mucormycosis caused by Lichtheimia resulted in death in four out of seven patients (57.1%).

Conclusion

These cases highlight the importance of early diagnosis and combined therapy for these sporadic yet life-threatening infections. Further studies on the diagnosis and control of Lichtheimia infection in China are required.

The TLR-NF-kB axis contributes to the monocytic inflammatory response against a virulent strain of Lichtheimia corymbifera, a causative agent of invasive mucormycosis

Invasive mucormycosis (IM) is a life-threatening infection caused by the fungal order Mucorales, its diagnosis is often delayed, and mortality rates range from 40-80% due to its rapid progression. Individuals suffering from hematological malignancies, diabetes mellitus, organ transplantations, and most recently COVID-19 are particularly susceptible to infection by Mucorales. Given the increase in the occurrence of these diseases, mucormycosis has emerged as one of the most common fungal infections in the last years. However, little is known about the host immune response to Mucorales. Therefore, we characterized the interaction among L. corymbifera—one of the most common causative agents of IM—and human monocytes, which are specialized phagocytes that play an instrumental role in the modulation of the inflammatory response against several pathogenic fungi. This study covered four relevant aspects of the host-pathogen interaction: i) The recognition of L. corymbifera by human monocytes. ii) The intracellular fate of L. corymbifera. iii) The inflammatory response by human monocytes against the most common causative agents of mucormycosis. iv) The main activated Pattern-Recognition Receptors (PRRs) inflammatory signaling cascades in response to L. corymbifera. Here, we demonstrate that L. corymbifera exhibits resistance to intracellular killing over 24 hours, does not germinate, and inflicts minimal damage to the host cell. Nonetheless, viable fungal spores of L. corymbifera induced early production of the pro-inflammatory cytokine IL-1β, and late release of TNF-α and IL-6 by human monocytes. Moreover, we revealed that IL-1β production predominantly depends on Toll-like receptors (TLRs) priming, especially via TLR4, while TNF-α is secreted via C-type lectin receptors (CTLs), and IL-6 is produced by synergistic activation of TLRs and CTLs. All these signaling pathways lead to the activation of NF-kB, a transcription factor that not only regulates the inflammatory response but also the apoptotic fate of monocytes during infection with L. corymbifera. Collectively, our findings provide new insights into the host-pathogen interactions, which may serve for future therapies to enhance the host inflammatory response to L. corymbifera.

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.

Hepatic failure and malnutrition as predisposing factors of cutaneous mucormycosis in a pediatric patient

The genus Lichtheimia is the third-most frequent genus isolated in mucormycosis. We report a cutaneous case caused by Lichtheimia ramosa, localized on the face of a pediatric patient, in the context of acute liver failure and caloric malnutrition. Several surgeries and treatment with liposomal amphotericin B enabled the patient's favorable evolution.

Work clothes as a vector for microorganisms: Accumulation, transport, and resuspension of microorganisms as demonstrated for waste collection workers

Work clothes may act as a vector for the transport of microorganisms leading to second-hand exposure; however, this has not been studied in work environments. We investigated whether microorganisms accumulate on workers' clothes in environments with elevated microbial exposures, and whether they are transported with the clothes and subsequently resuspended to the air. To study this, we selected waste collection workers and potential transport of bacteria and fungi to waste truck cabs via clothes, and compared the microbial communities within truck cabs, in waste collection workers' personal exposure, and on clean T-shirts worn by the workers. Microbial communities were also investigated for the presence of potentially harmful microorganisms. Results showed that microorganisms accumulated in large quantities (GM = 3.69 × 10⁵ CFU/m²/h for bacteria, GM = 8.29 × 10⁴ CFU/m²/h for fungi) on workers' clothes. The concentrations and species composition of airborne fungi in the truck cabs correlated significantly with the accumulation and composition of fungi on clothes and correlated to concentrations (a trend) and species composition of their personal exposures. The same patterns were not found for bacteria, indicating that work clothes to a lesser degree act as a vector for bacteria under waste collection workers' working conditions compared to fungi. Several pathogenic or allergenic microorganisms were present, e.g.: Klebsiella oxytoca, K. pneumoniae, Proteus mirabilis, Providencia rettgeri, Pseudomonas aeruginosa, and Aspergillus fumigatus, A. glaucus, A. nidulans, A. niger, and various Penicillium species. The potential 'take-home' exposure to these microorganisms are of most concern for immunocompromised or atopic individuals or people with open wounds or cuts. In conclusion, the large accumulation of microorganisms on workers' clothes combined with the overlap between fungal species for the different sample types, and the presence of pathogenic and allergenic microorganisms forms the basis for encouragement of good clothing hygiene during and post working hours.

Striatal necrosis caused by Lichtheimia ramosa in a neonatal calf

A 12-day-old male calf that did not want breast milk from birth died following neurological signs such as staggering. Postmortem examination revealed bleeding and encephalomalacia in the left striatum and frontal lobe. Histopathologically, necrotic granulomatous encephalitis with numerous fungi was detected. The fungi were positively stained with anti-Rhizomucor mouse monoclonal antibodies. Lichtheimia ramosa was detected in formalin-fixed paraffin-embedded samples of the affected tissue by molecular methods. To the best of our knowledge, striatal necrosis caused by L. ramosa in a neonatal calf has not been reported. This study provides the first evidence of striatal necrosis caused by L. ramosa in a neonatal calf.

Risk Assessment for Molds in the Vicinity of a Child Requiring Peritoneal Dialysis Living in a Rural Northern German Area

As well as severe immunosuppression, other predisposing factors may facilitate invasive mycosis caused by molds. Chronic kidney disease and the resulting peritoneal dialysis have been reported as factors putting patients at risk of fungal infections from environmental sources. We describe an environmental investigation undertaken to guide exposure prevention for a peritoneal dialysis patient with transient colonization of her nostrils by Lichtheimia corymbifera in a rural area of northern Germany. Systematic screening for airborne and surface-deposited molds enabled targeted recommendations to be made, although Lichtheimia corymbifera itself was not grown from the collected environmental samples. This communication is intended to illustrate how such an investigation can be performed on the basis of the environmental distribution of the molds and how preventive recommendations can be derived from the results.

Isolated pulmonary mucormycosis in an immunocompetent patient: a case report and systematic review of the literature

Background

Pulmonary mucormycosis caused by Mucorales is a highly lethal invasive fungal infection usually found in immunocompromised patients. Isolated pulmonary mucormycosis in immunocompetent patients is very rare. Here, we present a case of a 32-year-old male who developed pulmonary mucormycosis without any known immunodeficiency.

Case presentation

The patient presented to our hospital because of cough and chest pain along with blood in the sputum. He was first treated for community-acquired pneumonia until bronchoalveolar lavage fluid culture confirmed the growth of Absidia. His symptoms were relieved with the use of amphotericin B, and he eventually recovered. We also provide a systematic review of relevant literature to summarize the characteristics of pulmonary mucormycosis in immunocompetent patients.

Conclusions

Pulmonary mucormycosis has variable clinical presentations and is difficult to identify. Due to its high fatality rate, clinicians should make judgements regarding suspected cases correctly and in a timely manner to avoid misdiagnosis and delayed treatment.

First Case of Rhinocerebral Mucormycosis Caused by Lichtheimia ornata, with a Review of Lichtheimia Infections

BACKGROUND

Lichtheimia species are emerging opportunistic fungal pathogens in the Mucorales, causing serious skin and respiratory infections in immunocompromised patients. Established agents are Lichtheimia corymbifera and L. ramosa, while L. ornata is a novel agent. Available data on a species-specific analysis of Lichtheimia infections are limited.

METHODS

The first case of a fatal rhino-orbital-cerebral infection in a hematopoietic stem cell transplantation recipient caused by L. ornata is reported; the agent was identified by sequencing the ITS ribosomal region. We reviewed the literature on mucormycosis due to Lichtheimia species between 2009 and 2018, with an analysis of risk factors and epidemiological and clinical data.

RESULTS

In addition to our Lichtheimia ornata case, 44 cases of human Lichtheimia were analyzed. Lichtheimia predominated in Europe (68.2%), followed by Asia (16%), and Africa (9%). The most common underlying condition was hematological malignancy (36.3%), followed by trauma/major surgery (27.3%), while diabetes mellitus was rare (11.4%). Site of infection was mostly skin and soft tissues (45.5%) and lung (25%), while relatively few cases were disseminated (13.6%) or rhinocerebral (11.4%). Mortality (36.4%) was mainly due to disseminated and rhinocerebral infections.

CONCLUSION

In contrast to Rhizopus, the most common agent of mucormycosis recorded in patients with diabetes mellitus, Lichtheimia infections were primarily associated with hematological malignancies and major skin barrier damage. Given the fact that classical rhinocerebral mucormycosis remains difficult to treat, independent of causative species, timely application of amphotericin B accessory to debridement may be required for patient survival.

Identification of Dermatophyte and Nondermatophyte Molds Isolated from Animal Lesions Suspected to Dermatomycoses

Background:

Dermatomycoses contain superficial fungal infections of keratinized layers of the body such as skin, hair, and nail that affect more than 20%–25% of people and animals worldwide. Some fungi can cause superficial infections in animals after accidental penetration and colonization on injured skin and can be transmitted to humans by exposure. The infection caused mainly by dermatophyte species and may also be caused rarely by yeasts and nondermatophytic molds.

Materials and Methods:

Eighty-two skin scrapings and hair samples were collected from animals (sheep, cow, cat, camel, calf, goat, horse, and dog) in three specialized pet clinics and three livestock and slaughterhouses. The isolates were identified using direct microscopy, culture, and polymerase chain reaction-sequencing of ITS1-5.8SrDNA-ITS2 region.

Results:

Thirteen mold strains out of 82 clinical samples (15.8%) were isolated from animal lesions. Acremonium exuviarum (n = 4; 30.7%), Sarocladium implicatum (n = 2; 15.4%), Arthroderma otae (n = 2; 15.4%), Chaetomium iranianum (n = 1; 7.7%), Trichothecium roseum (n = 1; 7.7%), Lichtheimia ramosa (n = 1; 7.7%), Penicillium chrysogenum (n = 1; 7.7%), and Microsporum equinum (n = 1; 7.7%) were isolated from clinical specimens.

Conclusion:

Since opportunistic fungi are increasing as etiological agents of dermatomycoses, isolation of these molds from wounds can be a warning to veterinarians, and daily cleaning of wounds with a proper disinfectant is recommended for the prevention of fungal colonization.

Simultaneous detection of Aspergillus nidulans, Aspergillus luchuensis and Lichtheimia sp. in a bovine abortion

Abortion in dairy cattle may be caused by infectious (viruses, fungi and protozoa) and non-infectious causes mostly related to bad management practices and genetic factors. Recently, the significant contribution of mycotic infection to bovine abortion has been recognized. This report describes an abortion case in a Chianina cow due to Aspergillus nidulans, Aspergillus luchuensis and Lichtheimia sp. diagnosed by histology, cytology, culture and molecular assays. A mixed infection due to more than one fungus in abortion is rarely demonstrated. To our knowledge, this is the first case of bovine abortion caused by co-infection with three different moulds.

The geographical region of origin determines the phagocytic vulnerability of Lichtheimia strains

Mucormycoses are life-threatening infections that affect patients suffering from immune deficiencies. We performed phagocytosis assays confronting various strains of Lichtheimia species with alveolar macrophages, which form the first line of defence of the innate immune system. To investigate 17 strains from four different continents in a comparative fashion, transmitted light and confocal fluorescence microscopy was applied in combination with automated image analysis. This interdisciplinary approach enabled the objective and quantitative processing of the big volume of image data. Applying machine-learning supported methods, a spontaneous clustering of the strains was revealed in the space of phagocytic measures. This clustering was not driven by measures of fungal morphology but rather by the geographical origin of the fungal strains. Our study illustrates the crucial contribution of machine-learning supported automated image analysis to the qualitative discovery and quantitative comparison of major factors affecting host-pathogen interactions. We found that the phagocytic vulnerability of Lichtheimia species depends on their geographical origin, where strains within each geographic region behaved similarly, but strongly differed amongst the regions. Based on this clustering, we were able to also classify clinical isolates with regard to their potential geographical origin.

Animal Models to Study Mucormycosis

Mucormycosis is a rare but often fatal or debilitating infection caused by a diverse group of fungi. Animal models have been crucial in advancing our knowledge of mechanisms influencing the pathogenesis of mucormycoses, and to evaluate therapeutic strategies. This review describes the animal models established for mucormycosis, summarizes how they have been applied to study mucormycoses, and discusses the advantages and limitations of the different model systems.

Rhinocerebral Zygomycosis Due to a Lichtheimia ramosa Infection in a Calf: Neural Spread Through the Olfactory Nerves

Here, we report a case of rhinocerebral zygomycosis due to a Lichtheimia ramosa infection in a calf. A histopathological examination revealed that a fungus had invaded the brain through the olfactory nerves. Lichtheimia ramosa was detected by polymerase chain reaction analysis of DNA extracted from formalin-fixed paraffin-embedded samples of the affected tissue. This is the first case of rhinocerebral zygomycosis to involve cattle. Also, this is the first such case to involve fungal invasion into the central nervous system through the cranial nerve itself, rather than through perineural tissue.

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.

The genome sequence of four isolates from the family Lichtheimiaceae

This study reports the release of draft genome sequences of two isolates of Lichtheimia corymbifera and two isolates of L. ramosa. Phylogenetic analyses indicate that the two L. corymbifera strains (CDC-B2541 and 008-049) are closely related to the previously sequenced L. corymbifera isolate (FSU 9682) while our two L. ramosa strains CDC-B5399 and CDC-B5792 cluster apart from them. These genome sequences will further the understanding of intraspecies and interspecies genetic variation within the Mucoraceae family of pathogenic fungi.