Development of a loop-mediated isothermal amplification method for detection of Histoplasma capsulatum DNA in clinical samples

Diagnosis of Human Endemic Mycoses Caused by Thermally Dimorphic Fungi: From Classical to Molecular Methods

Human endemic mycoses are potentially fatal diseases caused by a diverse group of fungi that can alter their morphology in response to an increase in temperature. These thermally dimorphic fungi affect both healthy and immunocompromised hosts, causing a substantial health and economic burden. Despite this, the diagnosis of endemic mycoses is still a formidable challenge for several reasons, including similar symptomatology, limited utility of classical diagnostic methods, inaccessibility to reliable molecular approaches in most endemic areas, and a lack of clinical suspicion out of these regions. This review summarizes essential knowledge on thermally dimorphic fungi and the life-threatening diseases they cause. The principle, advantages and limitations of the methods traditionally used for their diagnosis are also described, along with the application status and future directions for the development of alternative diagnostic strategies, which could help to reduce the disease burden in endemic areas.

Loop-Mediated Isothermal Amplification for the Diagnosis of Sporotrichosis by Sporothrix brasiliensis

We aimed to develop and validate a Loop-mediated Isothermal Amplification (LAMP) assay to Sporothrix brasiliensis. LAMP reaction was developed using six primers designed based on calmodulin gene. In the LAMP reaction, we tested twenty isolates of S. brasiliensis from animals and humans, along with ten tissue samples extracted from the left footpad of mice that had been experimentally infected with S. brasiliensis. In addition, it included DNA samples from various other fungal species for specificity evaluation. All S. brasiliensis isolates yielded positive results in the LAMP, and the limit of DNA detection was 1 ng/μL. All murine samples were positive in the test while DNA from other fungal species were all negative, resulting in 100% of sensitivity and specificity of primers. LAMP diagnosis technique is a promising alternative to sporotrichosis diagnosis, in a simple and cost-effective way. Further studies are warranted to validate this technique using animal model samples obtained from both humans and animals.

Specific and sensitive loop-mediated isothermal amplification (LAMP) method for Madurella strains, eumycetoma filamentous fungi causative agent

BACKGROUND

Filamentous fungi of the genus Madurella are the primary causative agents of mycetoma, a disease observed in tropical and subtropical regions. Since early diagnostics based on a morphological approach are difficult and have many shortcomings, a molecular diagnostic method suitable for rural settings is required. In this study, we developed the loop-mediated isothermal amplification (LAMP) method to present a foundational technique of the diagnosis of Madurella spp. (M. mycetomatis, M. pseudomycetomatis, M. tropicana, and M. fahalii), the common causative organisms of eumycetoma.

PRINCIPAL FINDINGS

We successfully designed a primer pair targeting the rDNAs of three Madurella spp. excluding M. fahalii, and detected up to 100 fg of genomic DNA extracted from isolates of M. mycetomatis and 1 pg of M. pseudomycetomatis and M. tropicana, within one hour. Second, a primer pair specific to M. mycetomatis, the most common causative species, or M. fahalii, a drug-resistant species, was constructed, and the detection limit of both primer pairs was 1 pg. The designed primers accurately distinguished 16 strains of the genus Madurella from various fungal species known to cause mycetomas.

CONCLUSION

In summary, we established the first model of a LAMP detection method that rapidly and sensitively detects and identifies Madurella isolates for clinical diagnostics. Moreover, the combined designed primer sets could identify mycetoma-causing strains simultaneously.

A multicentre external quality assessment: A first step to standardise PCR protocols for the diagnosis of histoplasmosis and coccidioidomycosis

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.

Molecular Diagnosis of Endemic Mycoses

Diagnosis of endemic mycoses is still challenging. The moderated availability of reliable diagnostic methods, the lack of clinical suspicion out of endemic areas and the limitations of conventional techniques result in a late diagnosis that, in turn, delays the implementation of the correct antifungal therapy. In recent years, molecular methods have emerged as promising tools for the rapid diagnosis of endemic mycoses. However, the absence of a consensus among laboratories and the reduced availability of commercial tests compromises the diagnostic effectiveness of these methods. In this review, we summarize the advantages and limitations of molecular methods for the diagnosis of endemic mycoses.

Hemophagocytic Lymphohistiocytosis Secondary to Disseminated Histoplasmosis in HIV Seronegative Patients: A Case Report and Review of the Literature

Hemophagocytic lymphohistiocytosis (HLH) secondary to Histoplasma capsulatum infection is a rare disorder with poor outcome. Although cases of patients with human immunodeficiency virus (HIV) infection have been well documented, little study has reported in the setting of HIV seronegative. In this study, we report a case of HLH secondary to histoplasmosis in an immunocompetent patient in China and review all cases on this situation. The objective was to summary their epidemiology, clinical characteristics, diagnostic approaches, and therapeutic response. A 46-year-old male cooker presented fever, fatigue, anorexia, and weight loss. Bone marrow examination suggest fungus organism and hemophagocytosis, and further, bone marrow culture confirmed Histoplasma capsulatum, as the etiology of HLH. The patient was successfully treated. We reviewed a total of the 13 cases (including our patient) of HLH with histoplasmosis in intact immunology patients. Twelve of the 13 patients are from endemic areas, and nine of the 12 cases are from emerging endemic areas, India and China. Three patients had sojourn history may related to the disease onset. Twelve of the 13 cases fulfilled HLH-2004 criteria. The diagnosis of Histoplasma capsulatum infection was established by histological examination (13 of 13), culture (4 of 13), molecular method (2 of 13), and antigen or serological assays (2 of 13). Amphotericin B, posaconazole, and itraconazole show favorable activity against the fungus, seven patients used specific treatment for HLH. For analysis of outcomes, two of the 13 patients died. Our present case report and literature review show that disseminated Histoplasma capsulatum infection with HLH in the immunocompetent population becomes increasingly common in emerging endemic areas and have high mortality. It is necessary for clinicians to improve the awareness of disease diagnosis due to the atypical population and disease presentation. Timely diagnosis and early use of antifungal agents will lead to favorable prognosis.

[Management of Adult Community-Acquired Pneumonia and Prevention - Update 2021 - Guideline of the German Respiratory Society (DGP), the Paul-Ehrlich-Society for Chemotherapy (PEG), the German Society for Infectious Diseases (DGI), the German Society of Medical Intensive Care and Emergency Medicine (DGIIN), the German Viological Society (DGV), the Competence Network CAPNETZ, the German College of General Practitioneers and Family Physicians (DEGAM), the German Society for Geriatric Medicine (DGG), the German Palliative Society (DGP), the Austrian Society of Pneumology Society (ÖGP), the Austrian Society for Infectious and Tropical Diseases (ÖGIT), the Swiss Respiratory Society (SGP) and the Swiss Society for Infectious Diseases Society (SSI)]

The present guideline provides a new and updated concept of the management of adult patients with community-acquired pneumonia. It replaces the previous guideline dating from 2016.The guideline was worked out and agreed on following the standards of methodology of a S3-guideline. This includes a systematic literature search and grading, a structured discussion of recommendations supported by the literature as well as the declaration and assessment of potential conflicts of interests.The guideline has a focus on specific clinical circumstances, an update on severity assessment, and includes recommendations for an individualized selection of antimicrobial treatment.The recommendations aim at the same time at a structured assessment of risk for adverse outcome as well as an early determination of treatment goals in order to reduce mortality in patients with curative treatment goal and to provide palliation for patients with treatment restrictions.

Histoplasmosis

Histoplasmosis is one of the commonest endemic mycoses in the Americas yet is often underdiagnosed and neglected as a public health priority. This review outlines the evolving understanding of its epidemiology and the clinical syndromes of histoplasmosis, in addition to up-to-date diagnostic and treatment guidelines. A focus on histoplasmosis in advanced HIV is included. The challenges pertinent to histoplasmosis management in Latin America, with recommendations made through international expert consensus are discussed.

Diagnosis of Pulmonary Infections Due to Endemic Fungi

Endemic mycoses including Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, and Talaromyces are dimorphic fungi that can cause a variety of clinical manifestations, including respiratory infections. Their pulmonary presentations are variable, and diagnosis is often delayed as they can mimic other infectious and non-infectious causes of pulmonary disease. Delay in diagnosis can lead to unnecessary antibiotic use, repeat hospitalizations, and increased morbidity and mortality. The diagnosis of endemic fungal pulmonary infections often relies on multiple diagnostic tests including culture, tissue histopathology, antigen assays, and antibody assays. Due to the increased use of immunosuppressive agents and the widening geographic ranges where these infections are being found, the prevalence of endemic fungal infections is increasing. Physicians need to be aware of the clinical manifestations of pulmonary infections due to endemic fungal in order to ensure that the proper diagnostic work up is obtained promptly. A high index of suspicion is particularly important in patients with suspected pulmonary infections who have failed to improve despite antibiotics in the appropriate setting. We present a review diagnostic testing for pulmonary infections due to endemic mycoses.

Evaluation of a New Histoplasma spp. Quantitative RT-PCR Assay

Laboratory diagnosis of histoplasmosis is based on various methods, including microscopy, culture, antigen, and DNA detection of Histoplasma capsulatum var. capsulatum or Histoplasma capsulatum var. duboisii. To improve sensitivity of existing real-time quantitative PCR (qPCR) assays, we developed a new RT-qPCR assay that allows amplification of whole nucleic acids of Histoplasma spp. validated on suspected cases. The limit of detection was 20 copies, and the specificity against 114 fungal isolates/species was restricted to Histoplasma spp. Whole nucleic acids of 1319 prospectively collected consecutive samples from 907 patients suspected of having histoplasmosis were tested routinely between May 2015 and May 2019 in parallel with standard diagnostic procedures performed in parallel. Forty-four had proven histoplasmosis attributable to H. capsulatum var. capsulatum (n = 40) or H. capsulatum var. duboisii (n = 4) infections. The results of RT-qPCR were positive in 43 of 44 patients (97.7% sensitivity) in at least one specimen. Nine of 863 cases (99% specificity) were RT-qPCR positive and therefore classified as possible cases. RT-qPCR was positive in 13 of 30 (43.3%) blood samples tested in proven cases. A positive RT-qPCR result in blood was significantly associated with H. capsulatum var. capsulatum progressively disseminated histoplasmosis with a positive RT-qPCR result in 92.3% of the immunocompromised patients with disseminated disease. This new Histoplasma RT-qPCR assay enabling amplification of H. capsulatum var. capsulatum and H. capsulatum var. duboisii is highly sensitive and allows the diagnosis of histoplasmosis advantageously from blood and bronchoalveolar lavage fluid.

Diagnostic accuracy of antigen detection in urine and molecular assays testing in different clinical samples for the diagnosis of progressive disseminated histoplasmosis in patients living with HIV/AIDS: A prospective multicenter study in Mexico

BACKGROUND

The progressive disseminated histoplasmosis (PDH) has been associated with severe disease and high risk of death among people living with HIV (PLWHIV). Therefore, the purpose of this multicenter, prospective, double-blinded study done in ten Mexican hospitals was to determine the diagnostic accuracy of detecting Histoplasma capsulatum antigen in urine using the IMMY ALPHA Histoplasma EIA kit (IAHE), clarus Histoplasma GM Enzyme Immunoassay (cHGEI IMMY) and MiraVista Histoplasma Urine Antigen LFA (MVHUALFA); as well as the Hcp100 and 1281-1283220SCAR nested PCRs in blood, bone-marrow, tissue biopsies and urine.

METHODOLOGY/PRINCIPAL FINDINGS

We included 415 PLWHIV older than 18 years of age with suspicion of PDH. Using as diagnostic standard recovery of H. capsulatum in blood, bone marrow or tissue cultures, or histopathological exam compatible, detected 108 patients (26%, [95%CI, 21.78-30.22]) with proven-PDH. We analyzed 391 urine samples by the IAHE, cHGEI IMMY and MVHUALFA; the sensitivity/specificity values obtained were 67.3% (95% CI, 57.4-76.2) / 96.2% (95% CI, 93.2-98.0) for IAHE, 91.3% (95% CI, 84.2-96.0) / 90.9% (95% CI, 87.0-94.0) for cHGEI IMMY and 90.4% (95% CI, 83.0-95.3) / 92.3% (95% CI, 88.6-95.1) for MVHUALFA. The Hcp100 nested PCR was performed on 393, 343, 75 and 297, blood, bone marrow, tissue and urine samples respectively; the sensitivity/specificity values obtained were 62.9% (95%CI, 53.3-72.5)/ 89.5% (95%CI, 86.0-93.0), 65.9% (95%CI, 56.0-75.8)/ 89.0% (95%CI, 85.2-92.9), 62.1% (95%CI, 44.4-79.7)/ 82.6% (95%CI, 71.7-93.6) and 34.9% (95%CI, 24.8-46.2)/ 67.3% (95%CI, 60.6-73.5) respectively; and 1281-1283220SCAR nested PCR was performed on 392, 344, 75 and 291, respectively; the sensitivity/specificity values obtained were 65.3% (95% CI, 55.9-74.7)/ 58.8% (95%CI, 53.2-64.5), 70.8% (95%CI, 61.3-80.2)/ 52.9% (95%CI, 46.8-59.1), 71.4% (95%CI, 54.7-88.2)/ 40.4% (95%CI, 26.4-54.5) and 18.1% (95%CI, 10.5-28.1)/ 90.4% (95%CI, 85.5-94.0), respectively.

CONCLUSIONS/SIGNIFICANCE

The cHGEI IMMY and MVHUALFA tests showed excellent performance for the diagnosis of PDH in PLWHIV. The integration of these tests in clinical laboratories will certainly impact on early diagnosis and treatment.

Diagnosis of histoplasmosis: current status and perspectives

Histoplasmosis is a worldwide-distributed systemic mycosis caused by the dimorphic fungus Histoplasma capsulatum. Its clinical manifestations range from subclinical or mild respiratory illness to progressive disseminated histoplasmosis (PDH), a life-threatening disease, whose accurate diagnosis is still challenging and limited in many countries, where this disease is highly endemic. In this regard, Histoplasma antigen testing is now included in the WHO Essential Diagnostics List. The final diagnosis of histoplasmosis is established by culture and/or visualization of the yeast cells by cytology or histopathology using specific stains. However, both procedures have limited sensitivity to detect the disease and cultures are time-consuming. Antibody detection assays are effective for the subacute and chronic clinical forms of histoplasmosis. However, their sensitivity is low in the immunocompromised host. Several molecular "in-house" tests were also developed and showed promising results, but none of these tests are commercially available and their standardization and validation are still pending. Antigen detection assays have high sensitivity in PDH cases and are of great value for the follow-up of patients with histoplasmosis; however, cross-reactivity with other related fungi are common. In addition, this assay is expensive and only performed in few laboratories. Novel protein antigen candidates have been recently identified and produced by DNA-recombinant techniques in order to obtain standardized and specific reagents for the diagnosis of histoplasmosis, as opposed to the unspecific antigens or crude extracts currently used. This review describes the currently available assays, highlighting their strengths and limitations and reports the latest approaches to achieve reliable and rapid diagnostic tests for histoplasmosis. KEY POINTS: • PDH causes thousands of deaths per year globally. • Rapid accurate diagnosis of PDH is unfeasible in many regions. • Fast, accurate, and low-cost diagnostic alternatives are currently under development.

Current and New Perspectives in the Diagnosis of Blastomycosis and Histoplasmosis

The diagnosis of blastomycosis and histoplasmosis can be difficult for clinicians who rarely see infections caused by these environmentally restricted dimorphic fungi. Historically, the diagnosis of blastomycosis has been established by culture and sometimes by histopathologic identification. Currently, antigen detection in urine and serum has been shown to aid in the rapid diagnosis of blastomycosis, and newer antibody assays are likely to contribute to our diagnostic capability in the near future. The gold standard for the diagnosis of histoplasmosis has been culture of the organism from involved tissues, aided in some patients by histopathological verification of the typical yeast forms in tissues. Antigen detection has contributed greatly to the ability of clinicians to rapidly establish the diagnosis of histoplasmosis, especially in severely ill and immunocompromised patients, and antibody testing for Histoplasma capsulatum provides important adjunctive diagnostic capability for several forms of both acute and chronic histoplasmosis. For both of these endemic mycoses, novel molecular tests are under active investigation, but remain available in only a few reference laboratories. In this review, we provide a synopsis of diagnostic test options that aid in establishing whether a patient has blastomycosis or histoplasmosis.

Visible DNA microarray and loop-mediated isothermal amplification (LAMP) for the identification of Cryptococcus species recovered from culture medium and cerebrospinal fluid of patients with meningitis

Cryptococcal meningitis affects normal hosts and immunocompromised patients exhibiting high mortality rates. The objective of this study was to design two molecular assays, visible microarray platforms and loop-mediated isothermal amplification (LAMP), to identify Cryptococcus spp. and the species neoformans and gattii from the cerebral spinal fluid (CSF). To identify Cryptococcus and the two species, we designed two microarrays DNA platforms based on the internal transcribed spacer (ITS) region and CAP59 gene and LAMP assays specific for Cryptococcus species. The assays were tested using CSF from patients with cryptococcal meningitis. CSF from patients with cryptococcal meningitis was cultured in Sabouraud culture medium, and the Cryptococcus spp. grown in the culture medium were also tested for LAMP and microarray platforms. The results were compared to DNA sequencing of the same genetic regions. A total of 133 CSF samples were studied. Eleven CSFs were positive for Cryptococcus (9 C. neoformans and 2 C. gattii), 15 were positive for bacteria, and 107 were negative. The CAP59 platform correctly identified 73% of the CSF samples, while the ITS platform identified 45.5%. CAP59 platform correctly identified 100% of the Cryptococcus isolates, and ITS platform identified 70%. The two sets of LAMP primers correctly identified 100% of the Cryptococcus isolates. However, for CSF samples, the amplification occurred only in 55.5% of C. neoformans. The methodologies were reliable in the identification of Cryptococcus species, mainly for isolates from culture medium, and they might be applied as adjunctive tests to identify Cryptococcus species.

Isothermal nucleic acid amplification techniques for detection and identification of pathogenic fungi: A review

BACKGROUND

Fungal infections have increased during the last years due to the AIDS epidemic and immunosuppressive therapies. The available diagnostic methods, such as culture, histopathology and serology, have several drawbacks regarding sensitivity, specificity and time-consuming, while molecular methods are still expensive and dependent on many devices. In order to overcome these challenges, isothermal nucleic acid amplification techniques (INAT) arose as promising diagnostic methods for infectious diseases.

OBJECTIVE

This review aimed to present and discuss the main contributions of the isothermal nucleic acid amplification techniques applied in medical mycology.

METHODS

Papers containing terms for each INAT (NASBA, RCA, LAMP, CPA, SDA, HAD or PSR) and the terms 'mycoses' or 'disease, fungal' were obtained from National Center for Biotechnology Information database until August 2019.

RESULTS

NASBA, RCA, LAMP and PSR are the INAT reported in the literature for detection and identification of pathogenic fungi. Despite the need of a previous conventional PCR, the RCA technique might also be used for genotyping or cryptic species differentiation, which may be important for the treatment of certain mycoses; nevertheless, LAMP is the most used INAT for pathogen detection.

CONCLUSION

Among all INATs herein reviewed, LAMP seems to be the most appropriate method for fungal detection, since it is affordable, sensitive, specific, user-friendly, rapid, robust, equipment-free and deliverable to end-users, fulfilling all ASSURED criteria of the World Health Organization for an ideal diagnostic method.

Diagnosis and treatment of invasive fungal infections: looking ahead

Improved standards of care depend on the development of new laboratory diagnostic and imaging procedures and the development of new antifungal compounds. Immunochromatography technologies have led to the development of lateral flow devices for the diagnosis of cryptococcal meningitis and invasive aspergillosis (IA). Similar devices are being developed for the detection of histoplasmosis that meet the requirements for speed (∼15 min assay time) and ease of use for point-of-care diagnostics. The evolution of molecular tools for the detection of fungal pathogens has been slow but the introduction of new nucleic acid amplification techniques appears to be helpful, for example T2Candida. An Aspergillus proximity ligation assay has been developed for a rapid near-patient bedside diagnosis of IA. CT remains the cornerstone for radiological diagnosis of invasive pulmonary fungal infections. MRI of the lungs may be performed to avoid radiation exposure. MRI with T2-weighted turbo-spin-echo sequences exhibits sensitivity and specificity approaching that of CT for the diagnosis of invasive pulmonary aspergillosis. The final part of this review looks at new approaches to drug discovery that have yielded new classes with novel mechanisms of action. There are currently two new classes of antifungal drugs in Phase 2 study for systemic invasive fungal disease and one in Phase 1. These new antifungal drugs show promise in meeting unmet needs with oral and intravenous formulations available and some with decreased potential for drug-drug interactions. Novel mechanisms of action mean these agents are not susceptible to the common resistance mechanisms seen in Candida or Aspergillus. Modification of existing antifungal susceptibility testing techniques may be required to incorporate these new compounds.

The mycobiota of the human body: a spark can start a prairie fire

Mycobiota are inseparable from human health, shaking up the unique position held by bacteria among microorganisms. What is surprising is that this seemingly small species can trigger huge changes in the human body. Dysbiosis and invasion of mycobiota are confirmed to cause disease in different parts of the body. Meanwhile, our body also produces corresponding immune changes upon mycobiota infection. Several recent studies have made a connection between intestinal mycobiota and the human immune system. In this review, we focus on questions related to mycobiota, starting with an introduction of select species, then we summarize the typical diseases caused by mycobiota in different parts of the human body. Moreover, we constructed a framework for the human anti-fungal immune system based on genetics and immunology. Finally, the progression of fungal detection methods is also reviewed.

Evaluation and improvement of isothermal amplification methods for point-of-need plant disease diagnostics

A number of isothermal DNA amplification technologies claim to be ideal for point-of-need (PON) applications as they enable reactions to be performed using a single-temperature heat source (e.g. water bath). Thus, we examined several isothermal amplification methods focusing on simplicity, cost, sensitivity and reproducibility to identify the most suitable method(s) for low resource PON applications. A number of methods were found unsuitable as they either involved multiple temperature incubations, were relatively expensive or required relatively large amounts target DNA for amplification. Among the methods examined, loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) were found to be the most suitable for PON applications as they are both single step methods that provide highly sensitive and reproducible amplifications. The speed of LAMP reactions was greatly enhanced, up to 76%, with the addition of loop primers while the presence of swarm primers and the sequestration of free magnesium ions with nucleotides also enhanced the amplification speed. In contrast, we were unable to enhance RPA's performance from the original published literature. While both RPA and LAMP have some drawbacks, either isothermal technology can reliably be used for on-site diagnostics with minimal equipment.

Timely Diagnosis of Histoplasmosis in Non-endemic Countries: A Laboratory Challenge

Human histoplasmosis is a fungal infection caused by the inhalation of microconidia of the thermally dimorphic fungi Histoplasma capsulatum. Autochthonous cases of histoplasmosis have been diagnosed in almost every country, but it is considered an endemic infection in specific areas of the world. Many of them are popular travel destinations or the source of migratory movements. Thus, the vast majority of the registered cases in non-endemic countries are imported. They correspond to people having been exposed to the fungus in endemic locations as immigrants, expatriates, transient workers or tourists, with reported cases also associated to organ donation. Misdiagnosis and delays in initiation of treatment are not uncommon in cases of imported histoplasmosis. They are associated to high fatality-rates specially in patients with compromised cellular immunity in which progressive disseminated forms develop. The diagnosis of this infection in non-endemic countries is hampered by the lack of clinical suspicion and a dearth of available diagnostic tools adequate to offer rapid and accurate results. Non-culture-based assays such as nucleic-acid amplification tests present as a suitable alternative in this situation, offering improved sensitivity and specificity, shortened turnaround time, and increased biosafety by avoiding culture manipulation. In non-endemic regions, molecular techniques are being used mainly in laboratories from countries that have registered an increase in the incidence of imported cases. However, the number of published techniques is limited and lack consensus. Efforts are currently under way to standardize nucleic acid amplification-based techniques for its implementation in areas registering a rising number of imported cases.

The Role of Molecular Tests in the Diagnosis of Disseminated Histoplasmosis

Histoplasmosis is an emerging fungal disease, with global distribution. The disseminated form of the disease is a more severe infection, generally associated with AIDS. Classic diagnostic methods for histoplasmosis consist of microscopy, culture, and histopathology. More recently, the importance of Histoplasma antigen detection has dominated the literature on histoplasmosis diagnosis, but the relevance of molecular assays has not been as much studied. Here we describe the results of a systematic literature review focusing on studies that mainly compared immunological techniques (Histoplasma urine antigen detection) with molecular tests for the diagnosis of histoplasmosis. In addition to the review of comparative studies using such diagnostic techniques, the literature on polymerase chain reaction (PCR) tests in patients with disseminated histoplasmosis is also summarized. Two studies reported the comparison between immunological and molecular methods applied simultaneously for the diagnosis of disseminated histoplasmosis. PCR demonstrates a satisfactory performance assisting in the detection of Histoplasma spp. DNA in clinical samples.

Identification of Mycoses in Developing Countries

Extensive advances in technology offer a vast variety of diagnostic methods that save time and costs, but identification of fungal species causing human infections remains challenging in developing countries. Since the echinocandins, antifungals widely used to treat invasive mycoses, are still unavailable in developing countries where a considerable number of problematic fungal species are present, rapid and reliable identification is of paramount importance. Unaffordability, large footprints, lack of skilled personnel, and high costs associated with maintenance and infrastructure are the main factors precluding the establishment of high-precision technologies that can replace inexpensive yet time-consuming and inaccurate phenotypic methods. In addition, point-of-care lateral flow assay tests are available for the diagnosis of Aspergillus and Cryptococcus and are highly relevant for developing countries. An Aspergillus galactomannan lateral flow assay is also now available. Real-time PCR remains difficult to standardize and is not widespread in countries with limited resources. Isothermal and conventional PCR-based amplification assays may be alternative solutions. The combination of real-time PCR and serological assays can significantly increase diagnostic efficiency. However, this approach is too expensive for medical institutions in developing countries. Further advances in next-generation sequencing and other innovative technologies such as clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostic tools may lead to efficient, alternate methods that can be used in point-of-care assays, which may supplement or replace some of the current technologies and improve the diagnostics of fungal infections in developing countries.

Getting Histoplasmosis on the Map of International Recommendations for Patients with Advanced HIV Disease

Progressive disseminated histoplasmosis, caused by H. capsulatum, is a life-threatening illness and is an AIDS-defining opportunistic infection. It is neglected, worryingly under-diagnosed, and often misdiagnosed as cancer or tuberculosis with fatal consequences. Globally, over 100,000 cases of disseminated histoplasmosis have been estimated. In 2017, the World Health Organization (WHO) noted that disseminated histoplasmosis is a significant cause of mortality in AIDS patients. Through the rigorous efforts of the Global Action Fund for Fungal Infections (GAFFI) and partners, in 2019, the Histoplasma antigen test was included on the 2nd Edition of the WHO List of Essential Diagnostics. The drugs used in the treatment of histoplasmosis (amphotericin B and itraconazole) are on the WHO Essential Medicine List. The Manaus Declaration on histoplasmosis in the Americas and the Caribbean, where histoplasmosis kills more people with HIV than tuberculosis, advocates for universal access to rapid testing for histoplasmosis and availability of essential drugs for the treatment of histoplasmosis in every country by 2025. Hyperendemic areas are present in the Americas, Caribbean, Southeast Asia, and Latin America. In conclusion, histoplasmosis remains an important clinical and public health problem. To reduce HIV-associated mortality, disseminated histoplasmosis must be addressed through advocacy, increased awareness, and universal access to essential diagnostics and antifungal agents.

Loop-mediated Isothermal Amplification and nested PCR of the Internal Transcribed Spacer (ITS) for Histoplasma capsulatum detection

Background

Histoplasmosis is a neglected disease that affects mainly immunocompromised patients, presenting a progressive dissemination pattern and a high mortality rate, mainly due to delayed diagnosis, caused by slow fungal growth in culture. Therefore, a fast, suitable and cost-effective assay is required for the diagnosis of histoplasmosis in resource-limited laboratories. This study aimed to develop and evaluate two new molecular approaches for a more cost-effective diagnosis of histoplasmosis.

Methodology

Seeking a fast, suitable, sensitive, specific and low-cost molecular detection technique, we developed a new Loop-mediated Isothermal Amplification (LAMP) assay and nested PCR, both targeting the Internal Transcribed Spacer (ITS) multicopy region of Histoplasma capsulatum. The sensitivity was evaluated using 26 bone marrow and 1 whole blood specimens from patients suspected to have histoplasmosis and 5 whole blood samples from healthy subjects. All specimens were evaluated in culture, as a reference standard test, and Hcp100 nPCR, as a molecular reference test. A heparin-containing whole blood sample from a heathy subject was spiked with H. capsulatum cells and directly assayed with no previous DNA extraction.

Results

Both assays were able to detect down to 1 fg/μL of H. capsulatum DNA, and ITS LAMP results could also be revealed to the naked-eye by adding SYBR green to the reaction tube. In addition, both assays were able to detect all clades of Histoplasma capsulatum cryptic species complex. No cross-reaction with other fungal pathogens was presented. In comparison with Hcp100 nPCR, both assays reached 83% sensitivity and 92% specificity. Furthermore, ITS LAMP assay showed no need for DNA extraction, since it could be directly applied to crude whole blood specimens, with a limit of detection of 10 yeasts/μL.

Conclusion

ITS LAMP and nPCR assays have the potential to be used in conjunction with culture for early diagnosis of progressive disseminated histoplasmosis, allowing earlier, appropriate treatment of the patient. The possibility of applying ITS LAMP, as a direct assay, with no DNA extraction and purification steps, makes it suitable for resource-limited laboratories. However, more studies are necessary to validate ITS LAMP and nPCR as direct assay in other types of clinical specimens.

Histoplasmosis is a worldwide neglected disease with a high mortality rate associated with HIV/AIDS patients, killing more than tuberculosis in some endemic countries in Latin America. Part of this elevated mortality rate is due to delayed diagnosis and treatment. Here we present two novel methods, one based on Loop-mediated Isothermal Amplification (LAMP) and another on nested Polymerase Chain Reaction (nPCR), for fast, sensitive and specific diagnosis of histoplasmosis. Tests of blood samples spiked with Histoplasma capsulatum suggest the possibility of direct application of the LAMP assay proposed herein to clinical specimens without the need for previous DNA extraction and with the added advantage of naked-eye evaluation of the reaction results. Once the assay has been validated in different clinical specimens, it may be a promising tool for fast histoplasmosis screening.

Microfluidic Chip for Detection of Fungal Infections

Fungal infections can lead to severe clinical outcomes such as multiple organ failure and septic shock. Rapid detection of fungal infections allows clinicians to treat patients in a timely manner and improves clinical outcomes. Conventional detection methods include blood culture followed by plate culture and polymerase chain reaction. These methods are time-consuming and require expensive equipment, hence, they are not suitable for point-of-care and clinical settings. There is an unmet need to develop a rapid and inexpensive detection method for fungal infections such as candidemia. We developed an innovative immuno-based microfluidic device that can rapidly detect and capture Candida albicans from phosphate-buffered saline (PBS) and human whole blood. Our microchip technology showed an efficient capture of C. albicans in PBS with an efficiency of 61-78% at various concentrations ranging from 10 to 10⁵ colony-forming units per milliliter (cfu/mL). The presented microfluidic technology will be useful to screen for various pathogens at the point-of-care and clinical settings.

Molecular diagnostics in medical mycology

Diagnosing fungal infections poses a number of unique problems, including a decline in expertise needed for identifying fungi, and a reduced number of instruments and assays specific for fungal identification compared to that of bacteria and viruses.These problems are exacerbated by the fact that patients with fungal infections are often immunosuppressed, which predisposes to infections from both commonly and rarely seen fungi. In this review, we discuss current and future molecular technologies used for fungal identification, and some of the problems associated with development and implementation of these technologies in today’s clinical microbiology laboratories.

Diagnosing fungal infections poses a number of unique problems. In this Review, Wickes and Wiederhold discuss molecular technologies used for fungal identification, and the problems associated with their development and implementation in today’s clinical microbiology laboratories.

A novel method to control carryover contamination in isothermal nucleic acid amplification

We developed a novel method to control carryover contamination in loop-mediated isothermal amplification (LAMP) by primer engineering to carry recognition sites for a restriction endonuclease, providing a robust ability to eliminate carryover contaminants.

Comparison of diagnostic methods to detect Histoplasma capsulatum in serum and blood samples from AIDS patients

BACKGROUND

Although early and rapid detection of histoplasmosis is essential to prevent morbidity and mortality, few diagnostic tools are available in resource-limited areas, especially where it is endemic and HIV/AIDS is also epidemic. Thus, we compared conventional and molecular methods to detect Histoplasma capsulatum in sera and blood from HIV/AIDS patients.

METHODOLOGY

We collected a total of 40 samples from control volunteers and patients suspected of histoplasmosis, some of whom were also infected with other pathogens. Samples were then analyzed by mycological, serological, and molecular methods, and stratified as histoplasmostic with (group I) or without AIDS (group II), uninfected (group III), and infected with HIV and other pathogens only (group IV). All patients were receiving treatment for histoplasmosis and other infections at the time of sample collection.

RESULTS

Comparison of conventional methods with nested PCR using primers against H. capsulatum 18S rRNA (HC18S), 5.8S rRNA ITS (HC5.8S-ITS), and a 100 kDa protein (HC100) revealed that sensitivity against sera was highest for PCR with HC5.8S-ITS, followed by immunoblotting, double immunodiffusion, PCR with HC18S, and PCR with HC100. Specificity was equally high for double immunodiffusion, immunoblotting and PCR with HC100, followed for PCR with HC18S and HC5.8-ITS. Against blood, sensitivity was highest for PCR with HC5.8S-ITS, followed by PCR with HC18S, Giemsa staining, and PCR with HC100. Specificity was highest for Giemsa staining and PCR with HC100, followed by PCR with HC18S and HC5.8S-ITS. PCR was less efficient in patients with immunodeficiency due to HIV/AIDS and/or related diseases.

CONCLUSION

Molecular techniques may detect histoplasmosis even in cases with negative serology and mycology, potentially enabling early diagnosis.

Histoplasmosis in Africa: An emerging or a neglected disease?

Histoplasmosis in Africa has markedly increased since the advent of the HIV/AIDS epidemic but is under-recognised. Pulmonary histoplasmosis may be misdiagnosed as tuberculosis (TB). In the last six decades (1952-2017), 470 cases of histoplasmosis have been reported. HIV-infected patients accounted for 38% (178) of the cases. West Africa had the highest number of recorded cases with 179; the majority (162 cases) were caused by Histoplasma capsulatum var. dubuosii (Hcd). From the Southern African region, 150 cases have been reported, and the majority (119) were caused by H. capsulatum var. capsulatum (Hcc). There have been 12 histoplasmin skin test surveys with rates of 0% to 35% positivity. Most cases of Hcd presented as localised lesions in immunocompetent persons; however, it was disseminated in AIDS patients. Rapid diagnosis of histoplasmosis in Africa is only currently possible using microscopy; antigen testing and PCR are not available in most of Africa. Treatment requires amphotericin B and itraconazole, both of which are not licensed or available in several parts of Africa.

Standardization and validation of real time PCR assays for the diagnosis of histoplasmosis using three molecular targets in an animal model

Histoplasmosis is considered one of the most important endemic and systemic mycoses worldwide. Until now few molecular techniques have been developed for its diagnosis. The aim of this study was to develop and evaluate three real time PCR (qPCR) protocols for different protein-coding genes (100-kDa, H and M antigens) using an animal model. Fresh and formalin-fixed and paraffin-embedded (FFPE) lung tissues from BALB/c mice inoculated i.n. with 2.5x10⁶Histoplasma capsulatum yeast or PBS were obtained at 1, 2, 3, 4, 8, 12 and 16 weeks post-infection. A collection of DNA from cultures representing different clades of H. capsulatum (30 strains) and other medically relevant pathogens (36 strains of related fungi and Mycobacterium tuberculosis) were used to analyze sensitivity and specificity. Analytical sensitivity and specificity were 100% when DNAs from the different strains were tested. The highest fungal burden occurred at first week post-infection and complete fungal clearance was observed after the third week; similar results were obtained when the presence of H. capsulatum yeast cells was demonstrated in histopathological analysis. In the first week post-infection, all fresh and FFPE lung tissues from H. capsulatum-infected animals were positive for the qPCR protocols tested except for the M antigen protocol, which gave variable results when fresh lung tissue samples were analyzed. In the second week, all qPCR protocols showed variable results for both fresh and FFPE tissues. Samples from the infected mice at the remaining times post-infection and uninfected mice (controls) were negative for all protocols. Good agreement was observed between CFUs, histopathological analysis and qPCR results for the 100-kDa and H antigen protocols. We successfully standardized and validated three qPCR assays for detecting H. capsulatum DNA in fresh and FFPE tissues, and conclude that the 100-kDa and H antigen molecular assays are promising tests for diagnosing this mycosis.

Laboratory Diagnostics for Histoplasmosis

The diagnosis of histoplasmosis is based on a multifaceted approach that includes clinical, radiographic, and laboratory evidence of disease. The gold standards for laboratory diagnosis include demonstration of yeast on pathological examination of tissue and isolation of the mold in the culture of clinical specimens; however, antigen detection has provided a rapid, noninvasive, and highly sensitive method for diagnosis and is a useful marker of treatment response. Molecular methods with improved sensitivity on clinical specimens are being developed but are not yet ready for widespread clinical use. This review synthesizes currently available laboratory diagnostics for histoplasmosis, with an emphasis on complexities of testing and performance in various clinical contexts.

Progressive disseminated histoplasmosis: a systematic review on the performance of non-culture-based diagnostic tests

The diagnosis of progressive disseminated histoplasmosis is often a challenge to clinicians, especially due to the low sensitivity and long turnaround time of the classic diagnostic methods. In recent years, studies involving a variety of non-culture-based diagnostic tests have been published in the literature. We performed a systematic review by selecting studies evaluating non-culture-based diagnostic methods for progressive disseminated histoplasmosis. We searched for articles evaluating detection of antibody, antigens, as well as DNA-based diagnostic methods. A comprehensive PUBMED, Web of Science, and Cochrane Library search was performed between the years 1956 and 2016. Case reports, review articles, non-human models and series involving less than 10 patients were excluded. We found 278 articles and after initial review 18 articles were included: (12) involved antigen detection methods, (4) molecular methods, and (2) antibody detection methods. Here we demonstrate that the pursuit of new technologies is ultimately required for the early and accurate diagnosis of disseminated histoplasmosis. In particular, urinary antigen detection was the most accurate tool when compared with other diagnostic techniques.

Development and application of a rapid detection system for human papillomavirus and Herpes simplex virus-2 by loop-mediated isothermal amplification assay

Human papillomavirus (HPV) infection is an important factor that causes cervical cancer and non-melanoma skin cancer (NMSC), while HSV-2 plays an important role when HR-HPV triggers the cancer. Thus, a quick and convenient assay in the detection of HPV and HSV-2in the screening of HPV and HSV-2 infection is required. Two respective HPV and HSV-2 detection methods were established based on loop-mediated isothermal amplification (LAMP) assay. Specific outer primers, inner primers, and loop primers were designed according to the conserved domains of HPV and HSV-2 genomes, respectively, while degenerate primers were used for HPV assay. After optimizing the reaction conditions, the results were observed by LAMP Tubidimeter real-time LA-320. Standard plasmids HPV-L-P and HSV-2-L-P were cloned and used in sensitivity tests of HPV LAMP and HSV-2 LAMP, respectively. Fifty samples of actinic keratosis (AK), 20 samples of squamous cell carcinoma (SCC), 50 samples of basal cell carcinoma (BCC) and 20 samples of seborrheic keratosis (SK) were detected by HPV assay. Seventy three clinical samples of vaginitis, chronic cervicitis, cervical intraepithelial neoplasias and cervical cancer level positive were detected with HPV and HSV-2 assays. The reaction conditions of two assays were the same with a reaction temperature of 63 °C and a reaction time of 45 min. The sensitivity of HPV LAMP assay was 10 copies/μL, while that of the HSV-2 LAMP assay was 100 copies/μL. No cross-reactivity was observed. The HPV positive rates of AK, SCC, BCC and SK samples were 80% (40/50), 75% (15/20), 44% (22/50) and 21% (15/72), respectively. As an economic and quick diagnostic tool, LAMP assay is conducive to the extensive screening of HPV and HSV-2 and has huge potential to be promoted in resource-limited hospitals.

Point of Care Testing for the Diagnosis of Fungal Infections: Are We There Yet?

Diagnostic tools for invasive fungal infections have continuously improved within the last decades. Nowadays, cultural methods, antigen testing, and molecular tests, such as polymerase chain reaction, are widely used. These methods, however, are accompanied with different limitations as various availability, various turnaround time or high costs. A new generation of point-of-care test has shown promising results in various studies and may overcome some of these limitations. We therefore reviewed the literature for the most promising new point-of-care tests for invasive aspergillosis (Aspergillus-specific lateral-flow device test, Aspergillus proximity ligation antigen assay), cryptococcosis (cryptococcal lateral-flow assay), and for histoplasmosis (loop-mediated isothermal amplification assay).

Endemic Mycoses: What's New About Old Diseases?

Infections with geographically constrained dimorphic fungi cause the endemic mycoses, which include blastomycosis, coccidioidomycosis, emmonsiosis, histoplasmosis, paracoccidioidomycosis, sporotrichosis, and penicilliosis. In the last 5 years, our understanding of the epidemiology, diagnostics, and to a lesser extent management of these diseases has advanced. Specifically, the application of molecular techniques for genotyping fungal pathogens has resulted in the recognition of cryptic species within several genera, including Blastomyces, and Paracoccidioides; the reclassification of Penicillium marneffei, the agent of penicilliosis, to the genus Talaromyces; and the global emergence of dimorphic fungi of the genus Emmonsia, cause disease in immunocompromised persons. New and refined diagnostic tests are available based on the detection of circulating antigens and antibodies, mass spectrometry, and targeted gene amplification. In contrast, the development of new therapeutic options remains stalled, although isavuconazole may hold promise. Finally, advances have been made in the prospect of viable vaccines for preventing animal and human disease.

Molecular identification of Histoplasma capsulatum using rolling circle amplification

Histoplasmosis is a systemic fungal disease that occurs worldwide, causing symptomatic infection mostly in immunocompromised hosts. Etiological agent is the dimorphic fungus, Histoplasma capsulatum, which occurs in soil contaminated with bird or bat droppings. Major limitation in recognition of H. capsulatum infections is the low awareness, since other diseases may have similar symptomatology. The molecular methods have gained importance because of unambiguous diagnostic ability and efficiency. The aim of this study was to develop and evaluate a padlock probe in view of rolling circle amplification (RCA) detection method which targets ITS (Internal Transcribed Spacer) rDNA of H. capsulatum enabling rapid and specific detection of the fungus in clinical samples. Two padlock probes were designed and one of these (HcPL2) allowed specific amplification of H. capsulatum DNA while no cross-reactivity was observed with fungi used as negative controls. This method proved to be effective for H. capsulatum specific identification and demonstrated to be faster than the traditional method of microbiological identification.

Evaluation of two new enzyme immunoassay reagents for diagnosis of histoplasmosis in a cohort of clinically characterized patients

The performance characteristics of the recently available analyte-specific reagent based enzyme immunoassay (ASR-EIA) and in vitro diagnostic (IVD) kit for urine Histoplasma antigen detection were evaluated in a cohort of 50 clinically characterized patients with histoplasmosis and 50 control patients. Overall sensitivity and specificity of the ASR-EIA were significantly improved compared with those of the IVD kit (sensitivity 72% vs. 22%, P<.001, specificity 98% vs. 84%, P = .014). Fourteen specimens from patients with clinically characterized histoplasmosis (five with pulmonary histoplasmosis and nine with progressive disseminated histoplasmosis) were falsely negative by ASR-EIA. All 10 specimens from patients with severe symptoms of progressive disseminated histoplasmosis were positive by ASR-EIA, although the average reading value of these 10 specimens was not significantly different from that of others with positive results. Compared to the MiraVista antigen assay, both the IVD kit and the ASR-EIA were significantly less sensitive in detecting Histoplasma antigen in the urine of patients with histoplasmosis. The ASR-EIA and MiraVista assay had comparable specificity. In conclusion, the ASR-EIA has improved performance compared with the IVD kit in the detection of Histoplasma antigen in the urine. However, users should be aware of the potential for false negative results using the currently recommended cutoff value.

A simple, high-throughput, colourimetric, field applicable loop-mediated isothermal amplification (HtLAMP) assay for malaria elimination

BACKGROUND

To detect all malaria infections in elimination settings sensitive, high throughput and field deployable diagnostic tools are required. Loop-mediated isothermal amplification (LAMP) represents a possible field-applicable molecular diagnostic tool. However, current LAMP platforms are limited by their capacity for high throughput.

METHODS

A high-throughput LAMP (HtLAMP) platform amplifying mitochondrial targets using a 96-well microtitre plate platform, processing 85 samples and 11 controls, using hydroxynaphtholblue as a colourimetric indicator was optimized for the detection of malaria parasites. Objective confirmation of visually detectable colour change results was made using a spectrophotometer. A dilution series of laboratory-cultured 3D7 Plasmodium falciparum parasites was used to determine the limit of detection of the HtLAMP assay, using P. falciparum (HtLAMP-Pf) and Plasmodium genus (HtLAMP-Pg) primers, on whole blood and filter paper, and using different DNA extraction protocols. The diagnostic accuracy of HtLAMP was validated using clinical samples from Papua New Guinea, Malaysia, Ghana and The Gambia and its field applicability was evaluated in Kota Marudu district hospital, Sabah, Malaysia.

RESULTS

The HtLAMP assay proved to be a simple method generating a visually-detectable blue and purple colour change that could be objectively confirmed in a spectrophotometer at a wavelength of 600 nm. When compared with PCR, overall HtLAMP-Pg had a sensitivity of 98 % (n = 260/266, 95 % CI 95-99) and specificity 83 % (n = 15/18, 95 % CI 59-96). HtLAMP-Pf had a sensitivity of 97 % (n = 124/128, 95 % CI 92-99) and specificity of 96 % (n = 151/157, 95 % CI 92-99). A validation study in a regional hospital laboratory demonstrated ease of performance and interpretation of the HtLAMP assay. HtLAMP-Pf performed in this field setting had a sensitivity of 100 % (n = 17/17, 95 % CI 80-100) and specificity of 95 % (n = 123/128, 95 % CI 90-98) compared with multiplex PCR. HtLAMP-Pf also performed well on filter paper samples from asymptomatic Ghanaian children with a sensitivity of 88 % (n = 23/25, 95 % CI 69-97).

CONCLUSION

This colourimetric HtLAMP assay holds much promise as a field applicable molecular diagnostic tool for the purpose of malaria elimination.

Reevaluation of commercial reagents for detection of Histoplasma capsulatum antigen in urine

Detection of the Histoplasma capsulatum urinary antigen (UAg) is among the most sensitive and rapid means to diagnose histoplasmosis. Previously, we evaluated analyte-specific reagents (ASR) manufactured by IMMY (Norman, OK) for detection of Histoplasma galactomannan (GM) in urine using an enzyme immunoassay (EIA), and we showed low positive agreement (64.5%) with the MiraVista (MVista) Histoplasma antigen (Ag) quantitative EIA (MiraVista Diagnostics, Indianapolis, IN). Here we reevaluated the IMMY GM ASR following modification of our original assay protocol and introduction of an indeterminate range. A total of 150 prospectively collected urine samples were tested with both the IMMY and MVista EIAs, and clinical histories were recorded for all study subjects. The IMMY GM ASR showed positive and negative agreements of 82.3% (14/17 samples) and 100% (121/121 samples), respectively (with exclusion of 12 indeterminate results), and overall agreement of 90% (135/150 samples) with respect to the MVista EIA. Of the three patients with negative IMMY GM ASR results and positive MVista EIA results, testing was performed for initial diagnostic purposes for one patient (<0.4 ng/ml by the MVista EIA) and UAg levels were being monitored for the remaining two patients (both<0.7 ng/ml by the MVista EIA). The MVista EIA results were positive for 6/12 samples that tested indeterminate by the IMMY GM ASR. We also show that the IMMY GM ASR can be used to serially monitor Histoplasma UAg levels. In conclusion, we demonstrate that, with modification, the IMMY GM ASR is a reliable rapid assay for detection of Histoplasma UAg.

Diagnostic Methods for Histoplasmosis: Focus on Endemic Countries with Variable Infrastructure Levels

Diagnosis of histoplasmosis remains challenging in resource-limited regions where HIV/AIDS is epidemic and histoplasmosis is endemic. Early and rapid detection of histoplasmosis is essential to preventing morbidity and mortality, yet few diagnostic options are available in low-resource areas of the world. The aim of this review is to provide an overview of the current status of the diagnosis of histoplasmosis, including an update on recent developments and utilization of new technologies. We discuss the specific diagnostic challenges faced in endemic regions, emphasizing the need for greater availability and standardization of rapid diagnostics for this endemic and neglected disease. While significant progress has been made in the development of new methods, clinical utility must be established by means of formal and extensive clinical studies.

Histoplasmosis in HIV-Infected Patients: A Review of New Developments and Remaining Gaps

Histoplasma capsulatum is responsible for histoplasmosis, a fungal disease with worldwide distribution that can affect both immunocompromised and imunocompetent individuals. During the highly active antiretroviral therapy (HAART) era, morbidity and mortality due to histoplasmosis remained a public heatlh problem in low-income and high-income countries. The true burden of HIV-associated histoplasmosis is either not fully known or neglected since it is not a notifiable disease. Progress has been made in DNA patterns of strains and understanding of pathogenesis, and hopefully these will help identify new therapeutic targets. Unfortunately, histoplasmosis is still widely mistaken for multidrug-resistant tuberculosis, leading to numerous avoidable deaths, even if they are easily distinguishable. The new diagnostic tools and therapeutics developments have still not been made available in most endemic regions. Still, recent developments are promising because of their good clinical characteristics and also because they will be commercially available and affordable. This review of published data and gaps may help define and guide future research.