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Barros N, Wheat LJ. Histoplasmosis in Solid Organ Transplantation. J Fungi (Basel) 2024; 10:124. [PMID: 38392796 PMCID: PMC10890191 DOI: 10.3390/jof10020124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. It has a broad global distribution with shifting epidemiology during recent decades. While in immunocompetent individuals infection is usually self-resolving, solid organ transplant recipients are at increased risk of symptomatic disease with dissemination to extrapulmonary tissue. Diagnosis of histoplasmosis relies on direct observation of the pathogen (histopathology, cytopathology, and culture) or detection of antigens, antibodies, or nucleic acids. All transplant recipients with histoplasmosis warrant therapy, though the agent of choice and duration of therapy depends on the severity of disease. In the present article, we describe the pathogenesis, epidemiology, clinical manifestations and management of histoplasmosis in solid organ transplant recipients.
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Affiliation(s)
- Nicolas Barros
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Division of Infectious Diseases, Indiana University Health, Indianapolis, IN 46202, USA
- Miravista Diagnostics, Indianapolis, IN 46241, USA
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Puerta-Arias JD, Isaza Agudelo JP, Naranjo Preciado TW. Identification and production of novel potential pathogen-specific biomarkers for diagnosis of histoplasmosis. Microbiol Spectr 2023; 11:e0093923. [PMID: 37882565 PMCID: PMC10714873 DOI: 10.1128/spectrum.00939-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 09/08/2023] [Indexed: 10/27/2023] Open
Abstract
IMPORTANCE Histoplasmosis is considered one of the most important mycoses due to the increasing number of individuals susceptible to develop severe clinical forms, particularly those with HIV/AIDS or receiving immunosuppressive biological therapies, the high mortality rates reported when antifungal treatment is not initiated in a timely manner, and the limitations of conventional diagnostic methods. In this context, there is a clear need to improve the capacity of diagnostic tools to specifically detect the fungal pathogen, regardless of the patient's clinical condition or the presence of other co-infections. The proposed novel pathogen-specific biomarkers have the potential to be used in immunodiagnostic platforms and antifungal treatment monitoring in histoplasmosis. In addition, the bioinformatics strategy used in this study could be applied to identify potential diagnostic biomarkers in other models of fungal infection of public health importance.
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Affiliation(s)
- Juan David Puerta-Arias
- Medical and Experimental Mycology Group, Corporación para Investigaciones Biológicas (CIB-UdeA-UPB-UDES), Medellín, Colombia
- School of Health Sciences, Universidad Pontificia Bolivariana, Medellín, Colombia
- Universidad de Santander (UDES), Facultad de Ciencias Médicas y de la Salud, Bucaramanga, Colombia
| | | | - Tonny Williams Naranjo Preciado
- Medical and Experimental Mycology Group, Corporación para Investigaciones Biológicas (CIB-UdeA-UPB-UDES), Medellín, Colombia
- School of Health Sciences, Universidad Pontificia Bolivariana, Medellín, Colombia
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3
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Ibe C, Mnyambwa NP, Mfinanga SG. Emergomycosis in Africa: Time to Pay Attention to This Emerging Deadly Fungal Infection. Int J Gen Med 2023; 16:2313-2322. [PMID: 37309324 PMCID: PMC10257923 DOI: 10.2147/ijgm.s403797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 04/13/2023] [Indexed: 06/14/2023] Open
Abstract
Emergomycosis is an emerging deadly infectious disease caused primarily by a little-known airborne pathogen Emergomyces africanus, which can cause clinical management challenge especially in patients with advanced HIV disease. This minireview describes Es. africanus as the main cause of emergomycosis in Africa as well as considers contributing factors to the difficulties encountered in managing this infection. Emergomycosis is common in HIV-positive persons with low CD4 lymphocyte count and has an estimated fatality of 50%. The infection exhibits airborne transmission with pulmonary and extrapulmonary manifestations leading to skin lesions. However, the pathogenesis of Es. africanus is still poorly understood. The management of the infection is complicated due to lack of defined diagnostic and therapeutic guidelines. Limited expertise, poor research funding, and lack of awareness and national surveillance are thought to impact the recognition and prioritisation of the infection. These factors may ultimately assign emergomycosis a 'neglected infection status' even as it is suspected to be prevalent in more African countries than previously recognised. Increased awareness and integrated and targeted strategies such as mobilising manpower in clinical mycology are of paramount importance in managing emergomycosis in Africa and beyond.
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Affiliation(s)
- Chibuike Ibe
- Department of Microbiology, Faculty of Biological Sciences, Abia State University, Uturu, Nigeria
| | - Nicholaus P Mnyambwa
- National Institute for Medical Research, Muhimbili Research Centre, Dar es Salaam, Tanzania
- Alliance for Africa Health and Research (A4A), Dar es Salaam, Tanzania
| | - Sayoki G Mfinanga
- National Institute for Medical Research, Muhimbili Research Centre, Dar es Salaam, Tanzania
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Wilmes D, Hagen F, Verissimo C, Alanio A, Rickerts V, Buitrago MJ. A multicentre external quality assessment: A first step to standardise PCR protocols for the diagnosis of histoplasmosis and coccidioidomycosis. Mycoses 2023. [PMID: 37169736 DOI: 10.1111/myc.13603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/13/2023]
Abstract
BACKGROUND In-house real-time PCR (qPCR) is increasingly used to diagnose the so-called endemic mycoses as commercial assays are not widely available. OBJECTIVES To compare the performance of different molecular diagnostic assays for detecting Histoplasma capsulatum and Coccidioides spp. in five European reference laboratories. METHODS Two blinded external quality assessment (EQA) panels were sent to each laboratory that performed the analysis with their in-house assays. Both panels included a range of concentrations of H. capsulatum (n = 7) and Coccidioides spp. (n = 6), negative control and DNA from other fungi. Four laboratories used specific qPCRs, and one laboratory a broad-range fungal conventional PCR (cPCR) and a specific cPCR for H. capsulatum with subsequent sequencing. RESULTS qPCR assays were the most sensitive for the detection of H. capsulatum DNA. The lowest amount of H. capsulatum DNA detected was 1-4 fg, 0.1 pg and 10 pg for qPCRs, specific cPCR and broad-range cPCR, respectively. False positive results occurred with high concentrations of Blastomyces dermatitidis DNA in two laboratories and with Emergomyces spp. in one laboratory. For the Coccidioides panel, the lowest amount of DNA detected was 1-16 fg by qPCRs and 10 pg with the broad-range cPCR. One laboratory reported a false positive result by qPCR with high load of Uncinocarpus DNA. CONCLUSION All five laboratories were able to correctly detect H. capsulatum and Coccidioides spp. DNA and qPCRs had a better performance than specific cPCR and broad-range cPCR. EQAs may help standardise in-house molecular tests for the so-called endemic mycoses improving patient management.
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Affiliation(s)
- Dunja Wilmes
- FG16, Unit for Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
| | - Ferry Hagen
- Westerdijk Fungal Biodiversity Institute (WI-KNAW), Utrecht, The Netherlands
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Cristina Verissimo
- Department of Infectious Diseases, Reference Laboratory for Parasites and Fungal infections, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisbon, Portugal
| | - Alexandre Alanio
- Mycology Department, Translational Mycology Research Group, National Reference Center for Invasive Mycoses and Antifungals, Institut Pasteur, Université Paris Cité, Paris, France
- Laboratoire de Parasitologie-Mycologie, AP-HP, Hôpital Saint-Louis, Paris, France
| | - Volker Rickerts
- FG16, Unit for Mycotic and Parasitic Agents and Mycobacteria, Robert Koch Institute, Berlin, Germany
- Konsiliarlabor für Kryptokokkose und Seltene Systemmykosen, Robert Koch Institute, Berlin, Germany
| | - Maria José Buitrago
- Reference Mycology Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Madrid, Spain
- CIBERINFEC, ISCIII-CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
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Reddy DL, Nel J, Govender NP. Review: Emergomycosis. J Mycol Med 2023; 33:101313. [PMID: 36272380 DOI: 10.1016/j.mycmed.2022.101313] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 11/21/2022]
Abstract
Purpose of Review In this review, we provide an overview of emergomycosis from a clinical perspective and discuss the taxonomy and classification of the pathogens, epidemiology, pathophysiology of infection and mechanisms of pathogenesis, immunology, clinical manifestations, laboratory culture and diagnosis, molecular characterisation, therapy and prognosis. Recent Findings While Emergomyces pasteurianus is the most geographically-widespread species, Emergomyces africanus is endemic to Southern Africa and causes disseminated disease with cutaneous involvement primarily among patients with advanced human immunodeficiency virus (HIV) disease. Summary Emergomycosis, a disseminated clinical disease resulting from infection with dimorphic fungi in the genus Emergomyces, occurs primarily among immunocompromised patients. Further knowledge is needed on the pathophysiology, diagnosis and management of emergomycosis.
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Affiliation(s)
- Denasha L Reddy
- Division of Infectious Diseases, Department of Internal Medicine, Chris Hani Baragwanath Academic Hospital, University of the Witwatersrand, Johannesburg, South Africa.
| | - Jeremy Nel
- Division of Infectious Diseases, Department of Internal Medicine, Helen Joseph Hospital, University of the Witwatersrand, Johannesburg, South Africa.
| | - Nelesh P Govender
- National Institute for Communicable Diseases, a Division of the National Health Laboratory Service; School of Pathology, University of the Witwatersrand, Johannesburg, South Africa; Division of Medical Microbiology, University of Cape Town, South Africa; Institute of Infection and Immunity, St George's University of London, United Kingdom; MRC Centre for Medical Mycology, University of Exeter, United Kingdom.
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Validation of a Lateral Flow Assay for Rapid Diagnosis of Histoplasmosis in Advanced HIV Disease, Buenos Aires, Argentina. Appl Microbiol 2022. [DOI: 10.3390/applmicrobiol2040072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Histoplasmosis is a major cause of mortality in individuals with advanced human immunodeficiency virus (HIV) disease (AHD). We evaluated in patients with AHD a lateral flow assay (LFA) developed by MiraVista® Diagnostics (MVD LFA). Histoplasmosis was defined based on the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) case definitions. We also compared the results of this LFA with those obtained using a commercial enzyme immunoassay (EIA) developed by IMMY, Clarus Histoplasma GM EIA, IMMY (HGM EIA). A retrospective observational study was conducted at Hospital Juan A. Fernández, located in Buenos Aires, Argentina. The study included 48 urine specimens from patients aged >18 years with AHD. Urine specimens included 17 patients with disseminated histoplasmosis and 31 specimens from patients without evidence of histoplasmosis. Specimens were tested using the MVD LFA and the HGM EIA. The MVD LFA and the HGM EIA had similar analytical performance, with a sensitivity of 94%, specificity of 100%, positive predictive value of 100%, negative predictive value of 97%, and an accuracy of 98%. Comparison of the MVD LFA with the HGM EIA demonstrated a Kappa agreement index of 0.906. The LFA evaluated in this study had high analytical performance; it provided rapid diagnosis of histoplasmosis with minimal requirements for laboratory training, equipment, and laboratory infrastructure.
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Mapengo RE, Maphanga TG, Grayson W, Govender NP. Endemic mycoses in South Africa, 2010–2020: A decade-long description of laboratory-diagnosed cases and prospects for the future. PLoS Negl Trop Dis 2022; 16:e0010737. [PMID: 36170322 PMCID: PMC9518919 DOI: 10.1371/journal.pntd.0010737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 08/12/2022] [Indexed: 01/19/2023] Open
Abstract
Background Emergomycosis, histoplasmosis, sporotrichosis and blastomycosis are endemic to southern Africa; the first two are AIDS-related mycoses. We described laboratory-diagnosed cases of endemic and imported mycoses in South Africa over a decade and discuss available diagnostic tools, reasons for the current under-estimation of cases and future strategies to improve case ascertainment. Materials and methods We analysed electronic pathology laboratory data from all public laboratories and one large private laboratory in South Africa from 2010–2020. Diagnostic specimens processed at the national mycology reference laboratory were also included. We classified cases as proven, probable and possible based on the method of identification. Results We identified 682 cases, of which 307 were proven, 279 were probable and 96 were possible. Of 307 culture-confirmed cases, 168 were identified by phenotypic methods plus sequencing, 128 by phenotypic methods alone and 11 by direct PCR. Of 279 probable cases, 176 had yeasts observed on histology, 100 had a positive Histoplasma antigen test and 3 a positive pan-dimorphic PCR test. All 96 possible cases had compatible clinical syndrome with inflammatory infiltrates on skin tissue histology. A majority of cases had an unspecified endemic mycosis (207/682, 30.4%), followed by sporotrichosis (170/682, 24.9%), emergomycosis (154/682, 22.6%), histoplasmosis (133/682, 19.5%), blastomycosis (14/682, 2.1%) and talaromycosis (4/682, 0.6%). Conclusions This study reports a relatively low number of cases over a decade considering an estimated large population at risk, suggesting that a substantial fraction of cases may remain undiagnosed. There is a need to increase awareness among healthcare workers and to develop rapid point-of-care diagnostic tools and make these widely accessible. Emergomycosis, histoplasmosis, sporotrichosis and blastomycosis are serious fungal diseases which occur in southern Africa among people with either healthy or weakened immune systems. These fungal diseases may be missed because they mimic other diseases, occur together with other conditions that mask their presence or are simply not considered by healthcare workers. There are very few available simple diagnostic tests and most African countries do not conduct fungal disease surveillance. We described cases of these fungal diseases, which had been diagnosed in South African laboratories, from 2010–2020. We identified 682 cases, of which 307 were proven, 279 were probable and 96 were possible based on the available clinical and laboratory information. A majority of cases could not be allocated to one of the four disease types and were classified as unspecific endemic mycoses (30.4%). The remainder were sporotrichosis (24.9%), emergomycosis (22.3%), histoplasmosis (19.5%), blastomycosis (2.1%) and a travel-associated infection, talaromycosis (0.6%). We found relatively few cases considering the large population at risk. We believe that this could be due to the above-mentioned issues and insufficient expertise in diagnostic laboratories. There is a need to increase awareness among healthcare workers and to develop rapid point-of-care diagnostic tools and make these widely accessible.
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Affiliation(s)
- Rutendo E. Mapengo
- National Institute for Communicable Diseases (Centre for Healthcare-Associated Infections. Antimicrobial Resistance and Mycoses), a Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- * E-mail:
| | - Tsidiso G. Maphanga
- National Institute for Communicable Diseases (Centre for Healthcare-Associated Infections. Antimicrobial Resistance and Mycoses), a Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - Wayne Grayson
- Ampath National Reference Laboratory, Pretoria, South Africa
| | - Nelesh P. Govender
- National Institute for Communicable Diseases (Centre for Healthcare-Associated Infections. Antimicrobial Resistance and Mycoses), a Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Division of Medical Microbiology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
- Institute of Immunity and Infection, St George’s University of London, London, United Kingdom
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Almeida-Paes R, Bernardes-Engemann AR, da Silva Motta B, Pizzini CV, de Abreu Almeida M, de Medeiros Muniz M, Dias RAB, Zancopé-Oliveira RM. Immunologic Diagnosis of Endemic Mycoses. J Fungi (Basel) 2022; 8:jof8100993. [PMID: 36294558 PMCID: PMC9605100 DOI: 10.3390/jof8100993] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 12/02/2022] Open
Abstract
The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.
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Updates on Histoplasmosis in Solid Organ Transplantation. CURRENT FUNGAL INFECTION REPORTS 2022; 16:165-178. [PMID: 36097519 PMCID: PMC9453730 DOI: 10.1007/s12281-022-00441-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2022] [Indexed: 11/03/2022]
Abstract
Purpose of Review Recent Findings Summary
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Mah J, Bakker A, Tseng C, Lafay-Cousin L, Kuhn S, Brundler MA, Lisboa LF. Isolated Pulmonary Emergomycosis in an Immunocompetent Patient in Alberta, Canada. Open Forum Infect Dis 2022; 9:ofac021. [PMID: 35174253 PMCID: PMC8843081 DOI: 10.1093/ofid/ofac021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/11/2022] [Indexed: 11/30/2022] Open
Abstract
Emergomyces canadensis pulmonary infection was incidentally diagnosed in an asymptomatic patient suspected to have metastatic osteosarcoma. Molecular diagnosis was imperative to fungal identification given overlapping histopathological features with histoplasmosis. This report documents a case of isolated pulmonary emergomycosis in an otherwise immunocompetent patient while discussing diagnostic and management pitfalls of this emerging and underdiagnosed infection.
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Affiliation(s)
- Jordan Mah
- Section of Infectious Diseases, Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrea Bakker
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Calvin Tseng
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Lucie Lafay-Cousin
- Section of Pediatric Hematology Oncology and Bone Marrow Transplantation, Alberta Children's Hospital, University of Calgary, Calgary, Alberta, Canada
| | - Susan Kuhn
- Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Marie-Anne Brundler
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.,Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Luiz F Lisboa
- Section of Microbiology, Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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Validation and Concordance Analysis of a New Lateral Flow Assay for Detection of Histoplasma Antigen in Urine. J Fungi (Basel) 2021; 7:jof7100799. [PMID: 34682221 PMCID: PMC8539568 DOI: 10.3390/jof7100799] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 12/13/2022] Open
Abstract
Histoplasmosis is a major cause of mortality in people living with HIV (PLHIV). Rapid methods to diagnose Histoplasma capsulatum disease could dramatically decrease the time to initiate treatment, resulting in reduced mortality. The aim of this study was to validate a MiraVista® Diagnostics (MVD) Histoplasma urine antigen lateral flow assay (MVD LFA) for the detection of H. capsulatum antigen (Ag) in urine and compare this LFA against the MVista® Histoplasma Ag quantitative enzyme immunoassays (MVD EIA). We assessed the MVD LFA using a standardized reference panel of urine specimens from Colombia. We tested 100 urine specimens, 26 from PLHIV diagnosed with histoplasmosis, 42 from PLHIV with other infectious diseases, and 32 from non-HIV infected persons without histoplasmosis. Sensitivity and specificity of the MVD LFA was 96%, compared with 96% sensitivity and 77% specificity of the MVD EIA. Concordance analysis between MVD LFA and the MVD EIA displayed an 84% agreement, and a Kappa of 0.656. The MVD LFA evaluated in this study has several advantages, including a turnaround time for results of approximately 40 min, no need for complex laboratory infrastructure or highly trained laboratory personnel, use of urine specimens, and ease of performing.
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12
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New Histoplasma Diagnostic Assays Designed via Whole Genome Comparisons. J Fungi (Basel) 2021; 7:jof7070544. [PMID: 34356923 PMCID: PMC8305531 DOI: 10.3390/jof7070544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 12/16/2022] Open
Abstract
Histoplasmosis is a systemic fungal disease caused by the pathogen Histoplasma spp. that results in significant morbidity and mortality in persons with HIV/AIDS and can also affect immunocompetent individuals. Although some PCR and antigen-detection assays have been developed, conventional diagnosis has largely relied on culture, which can take weeks. Our aim was to provide a proof of principle for rationally designing and standardizing PCR assays based on Histoplasma-specific genomic sequences. Via automated comparisons of aligned genome contigs/scaffolds and gene (sub)sequences, we identified protein-coding genes that are present in existing sequences of Histoplasma strains but not in other genera. Two of the genes, PPK and CFP4, were used for designing primer sets for conventional and real-time PCR assays. Both resulted in a 100% analytical specificity in vitro and detected 62/62 H. capsulatum isolates using purified DNA. We also obtained positive detections of 2/2 confirmed H. capsulatum clinical FFPE (formalin-fixed paraffin-embedded) samples using both primer sets. Positive control plasmid 10-fold serial dilutions confirmed the analytical sensitivity of the assays. The findings suggest that these novel primer sets should allow for detection sensitivity and reduce false positive results/cross-reactions. New assays for detecting pathogenic fungi, constructed along these lines, could be simple and affordable to implement.
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Samaddar A, Sharma A. Emergomycosis, an Emerging Systemic Mycosis in Immunocompromised Patients: Current Trends and Future Prospects. Front Med (Lausanne) 2021; 8:670731. [PMID: 33968970 PMCID: PMC8104006 DOI: 10.3389/fmed.2021.670731] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 03/31/2021] [Indexed: 02/06/2023] Open
Abstract
Recently, the global emergence of emergomycosis, a systemic fungal infection caused by a novel dimorphic fungus Emergomyces species has been observed among immunocompromised individuals. Though initially classified under the genus Emmonsia, a taxonomic revision in 2017 based on DNA sequence analyses placed five Emmonsia-like fungi under a separate genus Emergomyces. These include Emergomyces pasteurianus, Emergomyces africanus, Emergomyces canadensis, Emergomyces orientalis, and Emergomyces europaeus. Emmonsia parva was renamed as Blastomyces parvus, while Emmonsia crescens and Emmonsia sola remained within the genus Emmonsia until a taxonomic revision in 2020 placed both the species under the genus Emergomyces. However, unlike other members of the genus, Emergomyces crescens and Emergomyces sola do not cause disseminated disease. The former causes adiaspiromycosis, a granulomatous pulmonary disease, while the latter has not been associated with human disease. So far, emergomycosis has been mapped across four continents: Asia, Europe, Africa and North America. However, considering the increasing prevalence of HIV/AIDS, it is presumed that the disease must have a worldwide distribution with many cases going undetected. Diagnosis of emergomycosis remains challenging. It should be considered in the differential diagnosis of histoplasmosis as there is considerable clinical and histopathological overlap between the two entities. Sequencing the internal transcribed spacer region of ribosomal DNA is considered as the gold standard for identification, but its application is compromised in resource limited settings. Serological tests are non-specific and demonstrate cross-reactivity with Histoplasma galactomannan antigen. Therefore, an affordable, accessible, and reliable diagnostic test is the need of the hour to enable its diagnosis in endemic regions and also for epidemiological surveillance. Currently, there are no consensus guidelines for the treatment of emergomycosis. The recommended regimen consists of amphotericin B (deoxycholate or liposomal formulation) for 1–2 weeks, followed by oral itraconazole for at least 12 months. This review elaborates the taxonomic, clinical, diagnostic, and therapeutic aspects of emergomycosis. It also enumerates several novel antifungal drugs which might hold promise in the treatment of this condition and therefore, can be potential areas of future studies.
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Affiliation(s)
- Arghadip Samaddar
- Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, India
| | - Anuradha Sharma
- Department of Microbiology, All India Institute of Medical Sciences, Jodhpur, India
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