Fumagillin-induced aseptic meningoencephalitis in a kidney transplant recipient with microsporidiosis

Encephalitozoon spp. as a potential human pathogen

Encephalitzoon spp. are microsporidia, and intracellular opportunistic pathogens. The hosts of these pathogens include vertebrates, invertebrates, and certain protozoa. In people microsporidia may be opportunistic pathogens for immunocompromised patients (with AIDS or after organ transplantation). Infection with these microorganisms was also described in persons with diarrhea and corneal diseases.

The species causing rare infections in humans, Encephalitozooncuniculi, had previously been described from animal hosts. However, several new microsporidial species, including E. intestinalis and E. hellem, have been discovered in humans, raising the question of their natural origin. Vertebrate animals are now identified as hosts for all three microsporidial species infecting humans, implying a zoonotic nature of these microorganisms. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is to present the zoonotic potential of E. intestinalis, E. cuniculi, and E. hellem.

Current Therapy and Therapeutic Targets for Microsporidiosis

Microsporidia are obligate intracellular, spore-forming parasitic fungi which are grouped with the Cryptomycota. They are both opportunistic pathogens in humans and emerging veterinary pathogens. In humans, they cause chronic diarrhea in immune-compromised patients and infection is associated with increased mortality. Besides their role in pébrine in sericulture, which was described in 1865, the prevalence and severity of microsporidiosis in beekeeping and aquaculture has increased markedly in recent decades. Therapy for these pathogens in medicine, veterinary, and agriculture has become a recent focus of attention. Currently, there are only a few commercially available antimicrosporidial drugs. New therapeutic agents are needed for these infections and this is an active area of investigation. In this article we provide a comprehensive summary of the current as well as several promising new agents for the treatment of microsporidiosis including: albendazole, fumagillin, nikkomycin, orlistat, synthetic polyamines, and quinolones. Therapeutic targets which could be utilized for the design of new drugs are also discussed including: tubulin, type 2 methionine aminopeptidase, polyamines, chitin synthases, topoisomerase IV, triosephosphate isomerase, and lipase. We also summarize reports on the utility of complementary and alternative medicine strategies including herbal extracts, propolis, and probiotics. This review should help facilitate drug development for combating microsporidiosis.

Safety and efficacy of fumagillin for the treatment of intestinal microsporidiosis. A French prospective cohort study

BACKGROUND

Intestinal microsporidiosis due to Enterocytozoon bieneusi is a cause of chronic diarrhoea in immunocompromised patients. Fumagillin has been approved in France for its treatment.

OBJECTIVES

To investigate the efficacy and safety of fumagillin in a real-life setting.

METHODS

As required by the French Medicine Agency, all patients receiving fumagillin were enrolled in a prospective study to evaluate its efficacy and safety. Stool examination with identification of E. bieneusi by PCR was performed at baseline, end of treatment and monthly thereafter for 6 months. Safety was monitored up to 6 months and full blood counts were monitored up to 42 days after treatment initiation. The primary endpoint was safety. Parasite clearance and relapses were secondary endpoints.

RESULTS

From 2007 to 2018, 166 patients received fumagillin, including 6 children. Patients were transplant recipients (84%), HIV-infected patients (13%) or had another cause of immunosuppression (5%). Serious adverse events were reported in 41 patients (25%), mainly thrombocytopenia (15%) and neutropenia (5%), with two haemorrhagic events leading to one death. Severe thrombocytopenia (<50 G/L) developed in 50 patients (29.6%), neutropenia (<1 G/L) in 20 patients (11.8%) and severe anaemia (<8 g/dL) in 21 patients (12.4%). At the end of treatment, 94% of patients with available stool examination (n = 132) had no spores detected. Among 99 patients with available follow-up after the end of treatment, three parasite relapses were documented.

CONCLUSIONS

E. bieneusi microsporidiosis was mainly diagnosed in transplant recipients. Fumagillin was associated with haematological toxicity but showed high efficacy with a low relapse rate.

Fumagillin, a Mycotoxin of Aspergillus fumigatus: Biosynthesis, Biological Activities, Detection, and Applications

Fumagillin is a mycotoxin produced, above all, by the saprophytic filamentous fungus Aspergillus fumigatus. This mold is an opportunistic pathogen that can cause invasive aspergillosis, a disease that has high mortality rates linked to it. Its ability to adapt to environmental stresses through the production of secondary metabolites, including several mycotoxins (gliotoxin, fumagillin, pseurotin A, etc.) also seem to play an important role in causing these infections. Since the discovery of the A. fumigatus fumagillin in 1949, many studies have focused on this toxin and in this review we gather all the information currently available. First of all, the structural characteristics of this mycotoxin and the different methods developed for its determination are given in detail. Then, the biosynthetic gene cluster and the metabolic pathway involved in its production and regulation are explained. The activity of fumagillin on its target, the methionine aminopeptidase type 2 (MetAP2) enzyme, and the effects of blocking this enzyme in the host are also described. Finally, the applications that this toxin and its derivatives have in different fields, such as the treatment of cancer and its microsporicidal activity in the treatment of honeybee hive infections with Nosema spp., are reviewed. Therefore, this work offers a complete review of all the information currently related to the fumagillin mycotoxin secreted by A. fumigatus, important because of its role in the fungal infection process but also because it has many other applications, notably in beekeeping, the treatment of infectious diseases, and in oncology.

A Case of Intestinal Microsporidiosis in a Renal Transplant Recipient

Post-renal transplant diarrhea is a common clinical presentation. An extensive list of potential etiology adds to the diagnostic dilemma. In cases of prolonged or intractable diarrhea, invasive tests are often performed. Intestinal microsporidia can be diagnosed with simple non-invasive stool polymerase chain reaction (PCR). Based on this case, we propose an easy to follow flow chart and present a literature review on post-renal transplant diarrhea. Further multicenter validation testing is required for the proposed flow chart.

Symptomatic respiratory Encephalitozoon cuniculi infection in renal transplant recipients

OBJECTIVES

Encephalitozoon spp. and Enterocytozoon bieneusi are intracellular parasitic fungi from the phylum Microsporidia, which initially localize to the intestine. As opportunistic pathogens, Encephalitozoon spp. in particular can disseminate to the respiratory tract, among other locations. Patients on life-long immunosuppression are at higher risk of such infections, mostly symptomatic.

METHODS

Sputum samples and bronchial washings from 72 renal transplant recipients and 105 patients with various respiratory diseases were screened for Encephalitozoon spp. and E. bieneusi by microscopic examination and genus-specific nested PCR followed by genotyping.

RESULTS

A total of 8.3% (6/72) of immunosuppressed renal transplant recipients and 1.9% (2/105) of patients with various respiratory diseases, both immunocompetent and immunosuppressed, were positive for respiratory microsporidial infection. All six transplant recipients were Encephalitozoon cuniculi-positive by PCR/sequencing and five of them suffered from respiratory symptoms. The presence of microsporidial spores was also confirmed microscopically in three of the transplant recipients. Of the two immunocompetent patients with various respiratory diseases, one had an E. cuniculi infection, while the second had an E. bieneusi infection.

CONCLUSIONS

Life-long immunosuppression in renal transplant recipients increases the risk of respiratory infection by E. cuniculi. Microsporidia should be screened in respiratory samples of these patients, particularly when they have respiratory symptoms.

Respiratory microsporidiosis caused by Enterocytozoon bieneusi in an HIV-negative hematopoietic stem cell transplant recipient

A 23-year-old, HIV-negative woman who had undergone a hematopoietic stem cell transplantation was admitted to the hospital with respiratory failure and symptoms of bronchiolitis obliterans. A chest computed tomography scan revealed diffuse ground-glass opacification and fibrous plugs. Due to worsening respiratory failure despite treatment, ventilation was provided through a tracheostomy tube. Molecular examination of bronchoalveolar lavage and urine revealed Enterocytozoon bieneusi infection. After treatment with albendazole the patient gradually improved, but the pathogen was not eradicated and reappeared on follow-up examination. E. bieneusi belongs to the most clinically important microsporidial species infecting humans, mostly those who are immunocompromised. This fungus tends to infect enterocytes of the intestine, and there are limited studies concerning its extraintestinal location. This is the first report of a case of disseminated respiratory and urinary E. bieneusi infection in a transplant recipient.

Confirmed microsporidial graft infection in a HIV-negative renal transplant recipient: A case report and review of the literature

Microsporidia are intracellular organisms most commonly known to cause opportunistic infection in patients with human immunodeficiency virus (HIV). There have been several case reports of infection in solid organ and bone marrow transplant recipients. Here, we report a case of a non-HIV-infected renal transplant patient with microsporidiosis of the renal tract associated with acute graft dysfunction. We also review the literature of 12 previously reported cases of microsporidiosis in patients with renal transplants who had described graft involvement. We review the pattern of illness as well as the common renal biopsy features when microsporidial infection is associated with renal graft infection.

Prevalence and molecular characteristics of urinary and intestinal microsporidia infections in renal transplant recipients

Transplant recipients have been identified as a new risk group for microsporidia infection. We characterize for the first time the prevalence of microsporidia in intestinal and urinary tracts of renal transplant recipients. Molecular examination of 86 patients showed that 25.5% of them were infected; 86% were confirmed to have pathogens in their urine and 45.5% in stool. Among positive patients, 32% had microsporidia confirmed in both urine and stool. Genotyping revealed Encephalitozoon cuniculi (59%) and Enterocytozoon bieneusi (23%) monoinfections as well as coinfections with both species (18%). Moreover, we found diarrhoea and fever as symptoms significantly associated with microsporidia presence. Our results indicate that microsporidial infection should be considered in the assessment of renal transplant recipients, especially in the urinary tract, even if asymptomatic. Molecular identification of microsporidia species is relevant because of their different susceptibility for treatment.

Concurrent infection of the urinary tract with Encephalitozoon cuniculi and Enterocytozoon bieneusi in a renal transplant recipient

A urinary tract coinfection, caused by Encephalitozoon cuniculi genotype II and Enterocytozoon bieneusi genotype D, was identified in an HIV-seronegative renal transplant recipient kept under lifelong immunosuppression. To our knowledge, this is the first report describing concurrent infection with these two microsporidia species in organ transplant recipients.