Successful treatment with fumagillin of the first pediatric case of digestive microsporidiosis in a liver-kidney transplant

The successful treatment of Enterocytozoon bieneusi Microsporidiosis with nitazoxanide in a patient with B-ALL: A Case Report

Introduction

Enterocytozoon bieneusi (E. bieneusi) Microsporidia can cause opportunistic infections in immunocompromised patients and is also an emerging disease in these individuals. Its clinical manifestations are chronic diarrhea and severe wasting syndrome, these can be extremely debilitating and carry a significant risk of death for immunocompromised patients. Often, microsporidia cannot be confirmed immediately by routine examination and culture. Effective and available treatment options are limited for infections caused by E. bieneusi in humans. Such cases are very rare in Chinese Mainland.

Case presentation

A 47-year-old male had recurrent, profuse watery diarrhea and abdominal discomfort for more than 7 months, with a fever for 5 days. Two years earlier, he received treatment with a modified BFM-90 protocol for acute B cell lymphoblastic leukemia and is currently in the final stages of maintenance therapy with oral methotrexate and mercaptopurine. The leukemia was assessed as still in remission two months ago. PET/CT showed massive peritoneal fluid accumulation and a high uptake area in the diffused peritoneum (SUVmax 12.57), suggesting tumor invasion or microbial infections. However, broad-spectrum antibacterial therapies were ineffective. Metagenomic sequencing of plasma and peritoneal fluid showed no suggestion of the existence of a tumor but instead showed a high sequence number of DNA and RNA of the Microsporidia. His albendazole treatment failed and subsequent treatment with nitazoxanide successfully resolved the infection.

Conclusion

This case shows that we should consider the possibility of atypical pathogen infection in patients with hematologic malignancy who repeatedly develop unexplained diarrhea with wasting. mNGS can help rule out malignant neoplasms and diagnose infections. Our results suggest that nitazoxanide effectively treats E. bieneusi microsporidia infections.

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.

Microsporidiosis in Humans

Microsporidia are obligate intracellular pathogens identified ∼150 years ago as the cause of pébrine, an economically important infection in silkworms. There are about 220 genera and 1,700 species of microsporidia, which are classified based on their ultrastructural features, developmental cycle, host-parasite relationship, and molecular analysis. Phylogenetic analysis suggests that microsporidia are related to the fungi, being grouped with the Cryptomycota as a basal branch or sister group to the fungi. Microsporidia can be transmitted by food and water and are likely zoonotic, as they parasitize a wide range of invertebrate and vertebrate hosts. Infection in humans occurs in both immunocompetent and immunodeficient hosts, e.g., in patients with organ transplantation, patients with advanced human immunodeficiency virus (HIV) infection, and patients receiving immune modulatory therapy such as anti-tumor necrosis factor alpha antibody. Clusters of infections due to latent infection in transplanted organs have also been demonstrated. Gastrointestinal infection is the most common manifestation; however, microsporidia can infect virtually any organ system, and infection has resulted in keratitis, myositis, cholecystitis, sinusitis, and encephalitis. Both albendazole and fumagillin have efficacy for the treatment of various species of microsporidia; however, albendazole has limited efficacy for the treatment of Enterocytozoon bieneusi. In addition, immune restoration can lead to resolution of infection. While the prevalence rate of microsporidiosis in patients with AIDS has fallen in the United States, due to the widespread use of combination antiretroviral therapy (cART), infection continues to occur throughout the world and is still seen in the United States in the setting of cART if a low CD4 count persists.

Microsporidiosis after liver transplantation: A French nationwide retrospective study

BACKGROUND

Microsporidiosis has been largely reported in patients with acquired immunodeficiency syndrome, but emerged as a cause of persistent diarrhea in solid organ transplant patients.

METHODS

Through the French Microsporidiosis Network and the Groupe français de recherche en greffe de foie, we collected all microsporidiosis cases identified in liver transplant patients between 1995 and 2020 in France.

RESULTS

We identified 24 liver transplant recipients with microsporidiosis. Sex ratio was balanced and median age was 58.8 (3.5-83.5) years (there were 4 children). Microsporidiosis occurred at a median time of 3.9 (0.1-18.9) years post-transplant. Median duration of diarrhea before diagnosis was 22 days (12-45). Therapeutic care included immunosuppressive therapy changes in 20 patients, as follows: stop cyclosporine or tacrolimus (n = 2), dose reduction of cyclosporine or tacrolimus (n = 12), stop MMF (n = 5), and dose reduction of corticosteroids (n = 1). In addition, 15 patients received specific therapy against microsporidiosis: fumagillin (n = 11) or albendazole (n = 4). Median duration of treatment was 14 days (8-45 days). Finally, 7 patients had immunosuppressive treatment tapering only. Microsporidiosis was complicated by renal failure in 15 patients, requiring dialysis in one case. Two patients had infection relapse. No patient presented proven rejection within the 3 months after microsporidiosis. None of the patients died within the 3 months after microsporidiosis.

CONCLUSIONS

Microsporidiosis is a very rare infection after liver transplantation but can induce severe dehydration and renal failure. Therefore, it must be systematically sought in any case of persistent diarrhea after first line screening of frequent infectious causes.

High Frequency of Enterocytozoon bieneusi Genotype WL12 Occurrence among Immunocompromised Patients with Intestinal Microsporidiosis

Microsporidiosis is an emerging opportunistic infection causing severe digestive disorders in immunocompromised patients. The aim of this study was to investigate the prevalence of intestinal microsporidia carriage among immunocompromised patients hospitalized at a major hospital complex in the Tunis capital area, Tunisia (North Africa), and perform molecular epidemiology and population structure analyses of Enterocytozoon bieneusi, which is an emerging fungal pathogen. We screened 250 stool samples for the presence of intestinal microsporidia from 171 patients, including 81 organ transplant recipients, 73 Human Immunodeficiency Virus (HIV)-positive patients, and 17 patients with unspecified immunodeficiency. Using a nested PCR-based diagnostic approach for the detection of E. bieneusi and Encephalitozoon spp., we identified 18 microsporidia-positive patients out of 171 (10.5%), among which 17 were infected with E. bieneusi. Microsporidia-positive cases displayed chronic diarrhea (17 out of 18), which was associated more with HIV rather than with immunosuppression other than HIV (12 out of 73 versus 6 out of 98, respectively, p = 0.02) and correlated with extended hospital stays compared to microsporidia-negative cases (60 versus 19 days on average, respectively; p = 0.001). Strikingly, internal transcribed spacer (ITS)-based genotyping of E. bieneusi strains revealed high-frequency occurrence of ITS sequences that were identical (n = 10) or similar (with one single polymorphic site, n = 3) to rare genotype WL12. Minimum-spanning tree analyses segregated the 17 E. bieneusi infection cases into four distinct genotypic clusters and confirmed the high prevalence of genotype WL12 in our patient population. Phylogenetic analyses allowed the mapping of all 17 E. bieneusi strains to zoonotic group 1 (subgroups 1a and 1b/1c), indicating loose host specificity and raising public health concern. Our study suggests a probable common source of E. bieneusi genotype WL12 transmission and prompts the implementation of a wider epidemiological investigation.

Renal Microsporidiosis in Pediatric Bone Marrow Transplant Recipients: A Case Series

Microsporidiosis is a rare, but emerging opportunistic infection in solid organ transplant and stem cell transplant recipients. Renal involvement in microsporidiosis is very rarely seen in these recipients. We describe two cases of pediatric renal microsporidiosis, diagnosed on renal biopsies, following bone marrow transplantation presenting as severe acute kidney injury. The first patient died, whereas the second survived due to early diagnosis based on high index of suspicion and prompt treatment with Albendazole. We believe these are the first such reported cases of renal microsporidiosis in pediatric bone marrow transplant recipients.

A new scope for orlistat: Effect of approved anti-obesity drug against experimental microsporidiosis

As the current therapies for intestinal microsporidiosis are either inconsistent in their efficacies or hampered by several adverse effects, alternative antimicrosporidial agents are being sought. The present study is the first that was designed to evaluate the potency of orlistat, an approved anti-obesity drug, against intestinal microsporidiosis caused by both Enterocytozoon bieneusi and Encephalitozoon intestinalis. Results were assessed through studying fecal and intestinal spore load, intestinal histopathological changes, viability, and infectivity of spores from treated animals. Results showed that orlistat has promising antimicrosporidia potential, with better results in E. intestinalis than E. bieneusi. The animals that received orlistat showed statistically significant decrease in the fecal and intestinal spore load, when compared to the corresponding control infected nontreated mice. The results were insignificant compared to fumagillin and albendazole. Light microscopic examination of stained intestinal sections revealed amelioration of the pathological changes and decreased inflammatory cells detected in the control infected nontreated mice. Spores encountered from stool of orlistat-treated E. bieneusi and E. intestinalis mice showed low viability and significant reduction of infectivity versus their control. Thus, considering the results of the present work, orlistat proved its effectiveness against the intestinal microsporidial infection.

Cryptosporidiosis and microsporidiosis as causes of diarrhea in kidney and/or pancreas transplant recipients

INTRODUCTION

Gastrointestinal disorders in solid organ recipients may have various origins including cryptosporidiosis and microsporidiosis. The prevalence of these infections is poorly known in solid organ transplant (SOT) patients in industrialized countries.

METHODS

We prospectively assessed the infectious causes of diarrhea in SOT patients. Secondary objectives were to gain further insight into the main characteristics of cryptosporidiosis, and to assess risk factors for this infection. All adult kidney and/or pancreas recipients presenting with diarrhea and admitted to our facility between May 1, 2014 and June 30, 2015 were enrolled. A stool sample was analyzed using a standardized protocol including bacteriological, virological, and parasitological investigations. Data related to clinical symptoms, immunosuppression, and environmental potential risk factors were collected through a self-administered questionnaire and computerized medical records.

RESULTS

Out of 73 enrolled patients, 36 had infectious diarrhea (49.3%). Viruses ranked first (17/36), followed by parasites and fungi (11/17). Cryptosporidiosis was the most common parasitic disease (n=6 patients). We observed four microsporidiosis cases. The estimated prevalence of cryptosporidiosis and microsporidiosis in this cohort was 3.7 and 2.4⁰/₀₀, respectively_. No significant risk factor for cryptosporidiosis or microsporidiosis, neither environmental nor immunological, could be evidenced.

CONCLUSION

Both cryptosporidiosis and microsporidiosis represent a significant cause of diarrhea in kidney transplant recipients.

Multiplex Real-time PCR Detection of Intestinal Protozoa in HIV-infected Children in Malawi: Enterocytozoon Bieneusi Is Common and Associated With Gastrointestinal Complaints and May Delay BMI (Nutritional Status) Recovery

BACKGROUND

Intestinal protozoa are common opportunistic infections in HIV patients. Longitudinal studies on either the clinical relevance or the effect of immune reconstitution by antiretroviral therapy on intestinal protozoan infections in children are lacking however. This study investigates prevalence and clinical relevance of intestinal protozoa in HIV-infected Malawian children before and during their first year of antiretroviral treatment (ART).

METHODS

Stool samples collected at enrolment and during follow-up were tested for nonopportunistic (Giardia lamblia, Dientamoeba fragilis, Entamoeba histolytica) and opportunistic protozoa (Enterocytozoon bieneusi, Encephalitozoon spp., Cryptosporidium spp. and Cystoisospora belli) using multiplex real-time polymerase chain reaction. Associations between infections and clinical symptoms were evaluated using univariate methods.

RESULTS

Nonopportunistic and opportunistic protozoa were detected in 40% (14/35) and 46% (16/35) of children at baseline, respectively. E. bieneusi was the most prevalent protozoa (37%, 13/35) and associated with gastrointestinal complaints (43% in positive (10/13) versus 18% (4/22) in E. bieneusi-negative children, P = 0.001. Body mass index recovery during 12 months of ART was more commonly delayed in E. bieneusi-positive children (+0.29 +standard deviation 0.83) than E. bieneusi-negative children (+1.03 +standard deviation 1.25; P = 0.05). E. bieneusi was not detected after 12 months of ART.

CONCLUSIONS

E. bieneusi was the most prevalent opportunistic intestinal protozoa, present in over a third of study participants before initiation of ART. Although all children cleared E. bieneusi after 12 months of ART, E. bieneusi was associated with gastrointestinal complaints and may delay body mass index recovery. Trials to assess effect of treatment of E. bieneusi on nutritional status should be considered in HIV-infected African children.

Intestinal microsporidiosis in Strasbourg from 2014 to 2016: emergence of an Enterocytozoon bieneusi genotype of Asian origin

Microsporidia cause opportunistic infections in highly immunodeficient individuals. Few studies on the epidemiology of these infections have been conducted in France. Between 2014 and 2016, we undertook a study to estimate the prevalence and circulating genotypes of this fungus-related micro-organism among the population of Strasbourg University Hospital. Samples were collected from hospitalized patients and analyzed using microscopy and molecular assays. Strains from positive subjects were sequenced for genotyping. Only 7/661 patients (1.1%) were positive for microsporidia, and the only species identified was Enterocytozoon bieneusi. Two patients presented immunodeficiency linked to AIDS, and five transplant recipients presented immunodeficiency linked to immunosuppressive therapies. Only five patients received specific antimicrosporidial treatment, but clinical outcomes were good in all cases. We identified four genotypes: A and D in patients with AIDS, and C and S9 in transplant recipients. To date, genotype S9 has been described only once. This genotype is similar to those found in farm animals in China. Because some of these animals have been introduced to Central Europe, we postulate that this genotype might be of Asian origin. Thus, genotyping microsporidial strains may be of epidemiological and clinical interest to identify potential outbreak sources depending on the infecting strains.

Enterocytozoon bieneusi Microsporidiosis in Stem Cell Transplant Recipients Treated with Fumagillin

Enterocytozoon bieneusi microsporidiosis is an emerging disease in immunocompromised patients. We report 2 cases of this disease in allogeneic hematopoietic stem cell transplant patients successfully treated with fumagillin. Thrombocytopenia occurred but without major adverse events. Modifications of immunosuppression could be avoided when E. bieneusi is rapidly identified and fumagillin therapy is started promptly.

Translating biosynthetic gene clusters into fungal armor and weaponry

Filamentous fungi are renowned for the production of a diverse array of secondary metabolites (SMs) where the genetic material required for synthesis of a SM is typically arrayed in a biosynthetic gene cluster (BGC). These natural products are valued for their bioactive properties stemming from their functions in fungal biology, key among those protection from abiotic and biotic stress and establishment of a secure niche. The producing fungus must not only avoid self-harm from endogenous SMs but also deliver specific SMs at the right time to the right tissue requiring biochemical aid. This review highlights functions of BGCs beyond the enzymatic assembly of SMs, considering the timing and location of SM production and other proteins in the clusters that control SM activity. Specifically, self-protection is provided by both BGC-encoded mechanisms and non-BGC subcellular containment of toxic SM precursors; delivery and timing is orchestrated through cellular trafficking patterns and stress- and developmental-responsive transcriptional programs.

Microsporidia-host interactions

Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related microbes has been poorly understood. Several new studies of the host transcriptional response to microsporidia infection have found infection-induced regulation of genes involved in innate immunity, ubiquitylation, metabolism, and hormonal signaling. In addition, microsporidia have recently been shown to exploit host recycling endocytosis for exit from intestinal cells, and to interact with host degradation pathways. Microsporidia infection has also been shown to profoundly affect behavior in insect hosts. Altogether, these and other recent findings are providing much-needed insight into the underlying mechanisms of microsporidia interaction with host animals.

Antiprotozoal Drugs

The Side Effects of Drugs Annuals is a series of volumes in which the adverse effects of drugs and adverse reactions to them are surveyed. The series supplements the contents of Meyler's Side Effects of Drugs: the International Encyclopedia of Adverse Drug Reactions and Interactions. This review of the July 2013 to December 2014 publications on antiprotozoal drugs covers various antimalarial drugs (4-aminoquinolines chloroquine and hydroxychloroquine, mefloquine, pyrimethamine, proguanil hydrochloride and atovaquone, quinine, artesunate, the combination of artesunate + pyronaridine, metronidazole and ornidazole). This review describes changes in the pharmacokinetics of antimalarial drugs, particularly first-line regimens of artemisinin-based compounds, lumefantrine, chloroquine and pyrimethamine + sulphadoxine that occur in pregnancy.

Potentiated anti-microsporidial activity of Lactobacillus acidophilus CH1 bacteriocin using gold nanoparticles

Through increased awareness and improved diagnostics, microsporidiosis has now been identified in a broader range of human populations; however current therapies are inconsistently effective. Recently, probiotics were determined as means for the control of intestinal parasitic infections through their secretory products; bacteriocins. This is the first study on the effect of bacteriocin produced by Lactobacillus acidophilus CH1 bacteriocin, with or without gold nanoparticles (Au-NPs), against intestinal microsporidiosis in immunosuppressed mice. Fecal and intestinal spore loads, besides viability, extrusion and infectivity of spores from treated animals were assessed. Results showed that the anti-microsporidial effects of bacteriocin were significantly potent. This efficiency was further potentiated upon conjugating bacteriocins with Au-NPs, as it induced a strikingly sustained reduction in fecal spore shedding after cessation of therapy by 1 week (94.26%). Furthermore, reduction in intestinal spore load was highest in bacteriocin/Au-NPs-inoculated mice (89.7%) followed by bacteriocin-inoculated group (73.5%). Spores encountered from stool of bacteriocin/Au-NPs group showed 92.4% viability, versus 93.7% in bacteriocin group. Spore extrusion and infectivity were most inhibited by exposure to bacteriocin/Au-NPs. Safety of bacteriocin/Au-NPs was also verified. Thus, considering the results of the present work, L. acidophilus CH1-derived bacteriocin can present a powerful safe therapy against intestinal microsporidiosis.