Histoplasma Antigen Detection Research Articles

Rapid CD4 Cell Count Determination and Cryptococcus and Histoplasma Antigen Detection in People Living with HIV: Implementation of a Package of Care Strategy in a Pilot Study, Argentina

ObjetivesDespite advancements in HIV diagnosis and treatment, advanced HIV disease (AHD) is still a significant concern globally, especially in countries with high percentage of undiagnosed cases and late-stage diagnoses. MethodsA prospective pilot study was conducted in Buenos Aires, Argentina to assess the feasibility of implementing a package for people living with HIV integrating a point-of-care CD4 test followed by rapid Cryptococcus and Histoplasma antigen (Ag) detection. ResultsA total of 105 PLHIV were enrolled, during June 2021-October 2021. The VISITECT® CD4-Advanced Disease LFA (CD4-LFA) classified 98 (93%) patients with AHD. Compared with flow cytometry (FCM), the CD4-LFA performed with high sensitivity (100%), but low specificity (19%), and limited accuracy (47%). In the 98 patients classified with AHD using the CD4-LFA, 16 tested positive for any of the rapid Ag used, including 12 patients positives for the Histoplasma Ag test and four positives for Cryptococcus Ag; all four patients with positive Cryptococcus Ag in sera and were diagnosed with meningitis. In the 30-day follow-up, one death was recorded. ConclusionsThe CD4-LFA correctly classified all patients with CD4 ≤200 cells/μL by FCM, but a high frequency of patients misclassified with AHD was recorded. We also observed a high prevalence of opportunistic fungal infections, as previously observed in the hospital where this pilot study was conducted, but in contrast with those previous reports, mortality was lower. The study underscores the importance of scaling up comprehensive care strategies and collaborating with governmental and non-governmental partners to enhance access to essential diagnostic tools and treatments for PLHIV. Further research with larger sample sizes is needed to validate these findings.

Detection of Histoplasma capsulatum and Blastomyces dermatitidis antigens in serum using a single quantitative enzyme immunoassay.

Histoplasma and Blastomyces antigen detection assays are commonly used diagnostic tools. However, a high level of cross-reactivity between these antigens prevents definitive pathogen identification by these assays alone. Retrospective analysis of 3,529 patients with Histoplasma and Blastomyces antigen testing performed on the same serum sample yielded an overall percent agreement of 99.3% (3,506 of 3,529; kappa: 0.859) between the two assays, suggesting that use of a single assay to detect both antigens may be an alternative diagnostic approach. We assessed performance of the Gotham BioTech Blastomyces antigen (GBA) enzyme immunoassay (EIA) (Portland, Maine) for detection of Blastomyces and Histoplasma antigens in serum. Comparison to the MiraVista Diagnostics Blastomyces (MVB) EIA showed 100% positive (24 of 24), negative (57 of 57), and overall (81 of 81) percent agreement. Additionally, 171 sera were used to compare the GBA EIA to the MiraVista Diagnostics Histoplasma (MVH) EIA, which showed 91.3% (63 of 69), 98% (100 of 102), and 95.3% (163 of 171) positive, negative, and overall percent agreement, respectively. Among eight patients with discordant GBA/MVH EIA results, seven had additional fungal testing performed, and results suggested that the MVH and GBA results were inaccurate for two and five samples, respectively. Overall, this study suggests that the GBA EIA has a high level of agreement with both of the commonly used, individual Blastomyces and Histoplasma antigen EIAs. By taking advantage of the high level of cross-reactivity between Blastomyces and Histoplasma antigen EIAs, utilization of a single antigen detection assay for these fungi provides an opportunity to optimize test utilization and decrease patient cost while maintaining a high level of diagnostic accuracy.

Histoplasma antigen detection in unconfirmed pulmonary tuberculosis and cross-reactivity with Aspergillus antigen in patients and in food in Jakarta, Indonesia.

H. capsulatum is endemic in Indonesia, but the value of Histoplasma antigen detection has not been studied. Histoplasma galactomannan (GM) ELISA was applied to sera of patients with unproven pulmonary tuberculosis (TB) and patients with a positive Aspergillus GM. Both Histoplasma and Aspergillus GM tests were performed to determine any possible cross-reaction with certain foods. Fourteen of 122 (11.5%) sera of patients with newly diagnosed clinical TB were positive for Histoplasma GM. The positivity rate in the serum of patients 5-6 and 12 months after TB diagnosis was 3.8% and 3.5%, respectively. Of 88 positive Aspergillus GM sera, 63 (71.6%) were also positive for Histoplasma GM. All tested foods were positive for Aspergillus GM, while 65% of foods were positive for Histoplasma GM. Galactomannan is widespread in sera and food in Jakarta, possibly related to food consumption. Histoplasma and Aspergillus antigen detection for the diagnosis will require additional means of confirming the diagnosis; negative tests may be more helpful for ruling out invasive histoplasmosis and aspergillosis.

Evaluation of an enzyme immunoassay and immunodiffusion for detection of anti-Histoplasma antibodies in serum from cats and dogs.

Histoplasma antigen and anti-Histoplasma antibody detection are used to support the diagnosis of histoplasmosis. There is a paucity of published data on antibody assays. Our primary hypothesis was that anti-Histoplasma immunoglobulin G (IgG) antibody detection using enzyme immunoassay (EIA) will be more sensitive as compared to immunodiffusion (ID). Thirty-seven cats and 22 dogs with proven or probable histoplasmosis; 157 negative control animals. Residual stored sera were tested for anti-Histoplasma antibodies using EIA and ID. Results of urine antigen EIA were reviewed retrospectively. Diagnostic sensitivity was calculated for all three assays and compared between immunoglobulin G (IgG) EIA and ID. The diagnostic sensitivity of urine antigen EIA and IgG EIA, interpreted in parallel, was reported. Sensitivity of IgG EIA was 30/37 (81.1%; 95% confidence interval [CI], 68.5%-93.4%) in cats and 17/22 (77.3%; 95% CI, 59.8%-94.8%) in dogs. Diagnostic sensitivity of ID was 0/37 (0%; 95% CI, 0%-9.5%) in cats and 3/22 (13.6%; 95% CI, 0%-28.0%) in dogs. Immunoglobulin G EIA was positive in all animals (2 cats and 2 dogs) with histoplasmosis but without detectable antigen in urine. Diagnostic specificity of IgG EIA was 18/19 (94.7%; 95% CI, 74.0%-99.9%) in cats and 128/138 (92.8%; 95% CI, 87.1%-96.5%) in dogs. Antibody detection by EIA can be used to support the diagnosis of histoplasmosis in cats and dogs. Immunodiffusion has an unacceptably low diagnostic sensitivity and is not recommended.

Optimization of a commercial Histoplasma galactomannan EIA test in a population from an endemic area of histoplasmosis in southern Brazil.

Since 2020 the World Health Organization (WHO) recommends Histoplasma antigen detection for the diagnosis of disseminated histoplasmosis (DH) in people living with HIV (PLHIV). Here we aimed to optimise the IMMY's Clarus® Histoplasma GM enzyme immunoassay (EIA), evaluating the best cut-off in the semi-quantitative (SQ-HGM EIA), also known as 'calibrator cut-off procedure'. The optimization was done using the quantitative standard procedure (Q-HGM EIA), also known as 'standard curve procedure', as reference test. A retrospective study from an endemic area of DH in southern Brazil was carried out including 264 patients investigated for DH using the test. Receiver Operator Characteristic curve was plotted, and sensitivity and specificity of the SQ-HGM EIA were calculated. The study included 24 positive (values ≥ 0.20 ng/ml) and 240 negative patients by the Q-HGM EIA. According to the manufacturer SQ-HGM EIA protocol, the new SQ-HGM EIA cut-off of 0.8 EIA units was validated, resulting in sensitivity and specificity of 88% and 98.7%, respectively. Our study pioneers and brings important data about the optimization of the Histoplasma antigen testing for the diagnosis of DH in a population from Southern Brazil. This optimization also reduced the amount of reagents used, lowering the cost associated with testing.

S10.2d Fungal beta-glucans and mannan performances in HIV-associated histoplasmosis

S10.2 Fungal Infections in Transplant Patients, September 24, 2022, 10:30 AM - 12:00 PMObjectivesDiagnosis of histoplasmosis in people living with HIV (PLWHIV) remains challenging despite developments in Histoplasma antigen and molecular detection tools. Fungal markers such as Beta-(1,3)-D-glucan (BDG) and galactomannan Aspergillus antigen (GM) are widely available, but the experience is limited during PLWHIV workup for suspicion of histoplasmosis. Our objective was to evaluate and compare BDG and GM performances for the diagnosis of HIV-associated histoplasmosis.MethodsWe performed a diagnostic accuracy study using primary serum samples stored frozen in a certified biorepository (CRB Amazonie-DC-2021-4649). Samples consisted of consecutive hospitalized PLWHIV unexposed to oral antifungals during the previous month (EDIRAPHIS study-NCT01884779). All patients gave consent for biobanking and ancillary studies on fungal markers.Histoplasmosis cases, proven (EORTC/MSG criteria) and probable (polyclonal or monoclonal Histoplasma antigen detections in urines or serum), as well as negative controls, were randomly selected. Patients with a proven or suspected Pneumocystis jirovecii infection were excluded. Following manufacturers’ instructions, samples were blindly tested for BDG and GM using Fungitell® and PlateliaTM Aspergillus Ag assays, respectively.Gold standard definition used three scenarios: EORTC scenario (cases and controls defined according to the EORTC/MSG 2020 criteria for endemic mycoses); strict scenario with proven cases restricted to those positives to all three previous Histoplasma antigen detections, and controls conversely negatives for all methods; and a large scenario with proven or probable cases and controls negatives for all methods.ResultsWe included 121 samples, 92 HIV-associated histoplasmosis cases (34 proven and 58 probable), and 29 negative controls. Compared with controls, histoplasmosis cases were significantly younger and advanced in the course of HIV disease [median CD4 count level 33/mm3 (15-87) vs 116 (62-245)].BDG and GM median detection levels were significantly higher among histoplasmosis cases compared with controls across all scenarios [368 (176-441) pg/ml vs 142 (89-211) for BDG and 2.5 (1.3-4.8) vs 0.19 (0.14-0.36) for GM, in cases vs controls of the strict scenario, respectively].In the strict scenario, at 150 pg/ml and 0.5 for BDG and GM respectively, sensitivity, specificity, positive and negative likelihood ratios were respectively: 95% [95%confidence interval (CI), 85-100] vs 90% [77-100], 52% [34-70] vs 83% [69-97], 2 [1.4-3.0] vs 5.3 [2.4-12.0], and 0.1 [0.01-0.7] vs 0.12 [0.03-0.45]. ROC curves found AUCs of 0.82 [0.68-0.91] vs 0.92 [0.80-0.98], and optimal thresholds at 288 pg/ml and 1.29, for BDG and GM, respectively (Fig. 1). Post-test probabilities showed best performances at the lowest thresholds for negative testing of both BDG and GM, and at the 0.7 thresholds for a positive GM test (Fig. 2).ConclusionBDG and GM may not be used for the same objective when searching for HIV-associated histoplasmosis. Although a negative BDG test at the lowest thresholds should rule out histoplasmosis in a screening context, limitations of a positive BDG test, even at the highest thresholds, call for a consecutive positive GM test before starting patients on antifungal therapy targeting histoplasmosis. Still, when considering the highest costs of BDG testing, higher balanced diagnostic performances, and lower costs of GM testing alone, one may favor the use of GM, notably in resources-limited settings.

721. Diagnosis of Histoplasmosis Using the MVista Histoplasma Galactomannan Antigen Qualitative Lateral Flow-Based Immunoassay; A Multicenter Study

Abstract Background Accurate and timely methods for the diagnosis of histoplasmosis in endemic resource-limited settings are largely lacking. Histoplasma galactomannan antigen detection by enzyme immunoassay (EIA) is the most widely used method for the diagnosis of acute pulmonary and disseminated histoplasmosis in the United States (USA). EIA methods have constraints in resource-limited settings including cost, turnaround time, and the need for large reference laboratories, leading to missed or delayed diagnoses and poor outcomes. Lateral flow assays (LFA) are practical methods that can be used in this setting for Histoplasma antigen detection. Methods Frozen urine specimens were submitted to MiraVista (MVista) for Histoplasma antigen EIA testing from three academic medical centers in highly endemic areas of the USA. They were also blinded and tested for the MVista Histoplasma LFA by skilled MVista technologists. Medical records were reviewed for clinical information. Patients were classified as controls or cases of histoplasmosis. Cases were divided into proven or probable, pulmonary, or disseminated, immune competent or immune suppressed, and mild, moderate, or severe. Results 352 subjects were enrolled, including 66 cases of histoplasmosis (44 proven, 22 probable) and 286 controls. Most of the cases were immunocompromised (68%). 76% had disseminated histoplasmosis. 6% were mild, 66% moderate, and 28% severe. A high degree of concordance was found between LFA and EIA results (kappa 0.837, OR 372.7, LR 204, p< 0.001). Overall, the sensitivity and specificity of the LFA were 78.8% and 99.3% respectively (kappa 0.84, p< 0.001). The sensitivity was higher in proven cases (93.2%), in patient with disseminated (94.7%), moderate (80%) and severe disease (94%), and those with galactomannan levels ≥ 2 ng/mL (97.7%). Specificity was 99.3% in proven cases, 99.3% in patient with moderate and severe disease, and 96.4% in those with galactomannan levels ≥ 2 ng/mL. Table 1. Statistical characteristics of the LFA test for histoplasmosis in different categories. PPV: Positive Predictive Value. NPV: Negative Predictive Value. EIA: Enzyme Immunoassay. The LFA test for histoplasmosis is more accurate in patients with high burden of infection. Conclusion The MVista Histoplasma galactomannan LFA may meet the need for accurate rapid diagnosis of histoplasmosis in resource-limited settings, especially in patients with relatively high disease burden, potentially reducing morbidity and mortality. Disclosures Melissa Minderman, Bachelor's Degree, Molecular Biology, MiraVista Diagnostics (Employee) Suphansa Gunn, Bachelor's Degree, psychology, MiraVista Diagnostics (Employee) Lawrence J. Wheat, MD, MiraVista Diagnostics (Employee)

Diagnosis of Histoplasmosis Using the MVista Histoplasma Galactomannan Antigen Qualitative Lateral Flow–Based Immunoassay: A Multicenter Study

Background Accurate and timely methods for the diagnosis of histoplasmosis in resource-limited countries are lacking. Histoplasma antigen detection by enzyme immunoassay (EIA) is widely used in the United States (US) but not in resource-limited countries, leading to missed or delayed diagnoses and poor outcomes. Lateral flow assays (LFAs) can be used in this setting.MethodsFrozen urine specimens were submitted to MiraVista diagnostics for antigen testing from 3 medical centers in endemic areas of the US. They were blinded and tested for the MVista Histoplasma LFA. Patients were classified as controls or cases of histoplasmosis. Cases were divided into proven or probable; pulmonary or disseminated; immunocompetent or immunosuppressed; and mild, moderate, or severe.ResultsThree hundred fifty-two subjects were enrolled, including 66 cases (44 proven, 22 probable) and 286 controls. Most of the cases were immunocompromised (71%), and 46 had disseminated and 20 had pulmonary histoplasmosis. Four cases were mild, 42 moderate, and 20 severe. LFA and EIA were highly concordant (κ = 0.84). Sensitivity and specificity of the LFA were 78.8% and 99.3%, respectively. LFA sensitivity was higher in proven cases (93.2%), patients with disseminated (91.3%), moderate (78.6%), and severe disease (80%), and those with galactomannan levels >1.8 ng/mL (97.8%). Specificity was 99.3% in proven cases, 99.3% in patients with moderate or severe disease, and 96.8% in those with galactomannan levels >1.8 ng/mL. Cross-reactivity was noted with other endemic mycoses.ConclusionsThe MVista Histoplasma LFA meets the need for accurate rapid diagnosis of histoplasmosis in resource-limited countries, especially in patients with high disease burden, potentially reducing morbidity and mortality.

Closing gaps in histoplasmosis: clinical characteristics and factors associated with probable/histoplasmosis in HIV/AIDS hospitalized patients, a retrospective cross-sectional study in two tertiary centers in Pereira, Colombia

BackgroundThe HIV pandemic continues to cause a high burden of morbidity and mortality due to delayed diagnosis. Histoplasmosis is prevalent in Latin America and Colombia, is difficult to diagnose and has a high mortality. Here we determined the clinical characteristics and risk factors of histoplasmosis in people living with HIV (PLWH) in Pereira, Colombia.Materials and methodsThis was a retrospective cross-sectional study (2014–2019) involving two tertiary medical centers in Pereira, Colombia. People hospitalized with HIV were included. Histoplasma antigen detection was performed in urine samples. Probable histoplasmosis was defined according to European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group/National Institute of Allergy and Infectious Diseases Mycoses Study Group criteria.Results172 HIV-infected patients were analyzed. Histoplasmosis was confirmed in 29% (n = 50/172) of patients. The logistic regression analysis showed that the risk factors for histoplasmosis were pancytopenia (OR 4.1, 95% CI 1.6–10.3, P = 0.002), < 50 CD4 + cells/μL (OR 3.1, 95% CI 1.3–7.3, P = 0.006) and Aspartate transaminase (AST) levels > 46 IU/L (OR 3.2, 95% CI 1.3–8, P = 0.010).ConclusionsHistoplasmosis is highly prevalent in hospitalized patients with HIV in Pereira, Colombia. The clinical findings are nonspecific, but there are some clinical abnormalities that can lead to suspicion of the disease, early diagnosis and prompt treatment. Urine antigen detection is useful for diagnosis, but is not widely available. An algorithmic approach is proposed for low-resource clinical settings.

Heterogeneity of Clinical Presentations and Paraclinical Explorations to Diagnose Disseminated Histoplasmosis in Patients with Advanced HIV: 34 Years of Experience in French Guiana.

We aimed to describe the ways patients with disseminated histoplasmosis—a multifaceted and often lethal disease—present themselves and are explored. A retrospective, observational, multicentric study spanned the period between 1 January 1981 and 1 October 2014. Principal component analysis was performed for the sampling sites and for the clinical signs and symptoms. The factor loadings of the principal components were selected for eigenvalues > 1. The most frequent signs and symptoms were an alteration of the WHO general performance status, fever, digestive tract, respiratory signs and symptoms and lymphadenopathies. The most common sites sampled were bone marrow, respiratory tract, blood, lymph node and liver biopsies, with significant variations in the number of sites from which samples were taken to try to identify the pathogen. The principal component analysis clinical signs and symptoms leading to the diagnosis showed four main lines of variation. The factor loadings of the four main components were compatible with four broad types of clinical presentations and four types of exploration strategies. Extracting simple algorithms was difficult, emphasizing the importance of clinical expertise when diagnosis depends on obtaining a sample where Histoplasma can be seen or grown. Histoplasma antigen detection tests will help simplifying the algorithms.

HIV-Associated Histoplasmosis: Current Perspectives.

Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum. Infection develops by inhalation of microconidia from environmental sites inhabited by birds and bats. Disseminated disease is the usual presentation due to impaired cellular immunity. Common clinical manifestations include fever, fatigue, malaise, anorexia, weight loss, and respiratory symptoms. Histoplasma antigen detection is the most sensitive method for diagnosis. The sensitivity of the MVista® Quantitative Histoplasma antigen enzyme immunoassay is 95–100% in urine, over 90% in serum and bronchoalveolar lavage (BAL) antigen and 78% in cerebral spinal fluid (CSF). A proven diagnosis can be established by culture or pathology with sensitivities between 70% and 80%. The sensitivity of antibody detection by immunodiffusion or complement fixation was between 60% and 70%. Diagnosis using molecular methods has not been adequately validated for implementation and FDA cleared assays are unavailable. Liposomal amphotericin B should be used for 1–2 weeks followed by itraconazole for at least one year until CD4 counts are above 150 cells/mm3, HIV viral load is below 400 copies/mL and Histoplasma urine antigen is negative. Serum itraconazole level should be monitored to avoid drug toxicity. Antigen should be measured periodically to establish that treatment is effective and to assist in identifying relapse. The incidence of immune reconstitution inflammatory syndrome is low but it must be considered in patients who are thought to be failing antifungal treatment as it does not respond to changing antifungal agents but rather to initiation of corticosteroid therapy. In this review, we discuss pathogenesis, clinical manifestations, diagnosis and treatment based on personal experience and relevant publications.

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.

Histoplasmosis, An Underdiagnosed Disease Affecting People Living With HIV/AIDS in Brazil: Results of a Multicenter Prospective Cohort Study Using Both Classical Mycology Tests and Histoplasma Urine Antigen Detection.

BackgroundHistoplasmosis is highly endemic in the American continent. This condition is associated with a high mortality, particularly in people living with HIV/AIDS (PLWHA). Diagnosis of histoplasmosis is usually late in South America, as Histoplasma antigen detection is rarely available. Here we determined the prevalence, risk factors, and outcome of histoplasmosis in PLWHA in Brazilian hospitals.MethodsThis was a prospective cohort study (2016–2018) involving 14 tertiary medical centers in Brazil. We included hospitalized PLWHA presenting with fever and additional clinical findings. Patients were investigated at each participant center with classical mycology methods. Also, Histoplasma antigen detection was performed in urine samples (IMMY). Probable/proven histoplasmosis was defined according to European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group/National Institute of Allergy and Infectious Diseases Mycoses Study Group criteria.ResultsFrom 616 eligible patients, 570 were included. Histoplasmosis was identified in 21.6% (123/570) of patients. Urine antigen testing increased the diagnostic yield in 53.8%, in comparison with standard mycology methods. Variables independently associated with histoplasmosis were CD4+ count <50 cells/mm3, use of an antiretroviral (protective effect), and sample collection in the Northeast region of Brazil. Dyspnea at presentation was independently associated with death. Histoplasmosis was more frequent than tuberculosis in patients with low CD4+ counts. Overall 30-day mortality was 22.1%, decreasing to 14.3% in patients with antigen-based diagnosis.ConclusionsHistoplasmosis is a very frequent condition affecting PLWHA in Brazil, particularly when CD4+ counts are lower than 50 cells/mm3. Antigen detection may detect earlier disease, with a probable impact on outcomes. Access to this diagnostic tool is needed to improve clinical management of PLWHA in endemic countries.

Histoplasma capsulatum antigen detection tests as an essential diagnostic tool for patients with advanced HIV disease in low and middle income countries: A systematic review of diagnostic accuracy studies.

IntroductionDisseminated histoplasmosis, a disease that often resembles and is mistaken for tuberculosis, is a major cause of death in patients with advanced HIV disease. Histoplasma antigen detection tests are an important addition to the diagnostic arsenal for patients with advanced HIV disease and should be considered for inclusion on the World Health Organization Essential Diagnostics List.ObjectiveOur objective was to systematically review the literature to evaluate the diagnostic accuracy of Histoplasma antigen tests in the context of advanced HIV disease, with a focus on low- and middle-income countries.MethodsA systematic review of the published literature extracted data on comparator groups, type of histoplasmosis, HIV status, performance results, patient numbers, whether patients were consecutively enrolled or if the study used biobank samples. PubMed, Scopus, Lilacs and Scielo databases were searched for published articles between 1981 and 2018. There was no language restriction.ResultsOf 1327 screened abstracts we included a total of 16 studies in humans for further analysis. Most studies included used a heterogeneousgroup of patients, often without HIV or mixing HIV and non HIV patients, with disseminated or non-disseminated forms of histoplasmosis. Six studies did not systematically use mycologically confirmed cases as a gold standard but compared antigen detection tests against another antigen detection test. Patient numbers were generally small (19–65) in individual studies and, in most (7/10), no confidence intervals were given. The post test probability of a positive or negative test were good suggesting that this non invasive diagnostic tool would be very useful for HIV care givers at the level of reference hospitals or hospitals with the infrastructure to perform ELISA tests. The first results evaluating point of care antigen detection tests using a lateral flow assay were promising with high sensitivity and specificity.ConclusionsAntigen detection tests are promising tools to improve detection of and ultimately reduce the burden of histoplasmosis mortality in patients with advanced HIV disease.

Unusual Presentation of Disseminated Histoplasmosis

Histoplasma capsulatum is the most common endemic mycosis in the United States and in rare cases, it could progress to disseminated histoplasmosis in immunocompromised patients. Hepatic manifestations as the primary presenting symptom are uncommon. Fever is the most common symptom in disseminated histoplasmosis, and gastrointestinal symptoms have been reported to be rare, which makes it a diagnostic challenge. We present a 61-year-old female with past medical history of rheumatoid arthritis who had been treated with Plaquenil in the past, presented with abdominal pain, jaundice, fever, chills and poor appetite. Vitals were remarkable for blood pressure of 129/63 mmhg, pulse of 111 beats per minute, temperature of 102.2 °F (oral), respiratory rate of 19 breaths per minute. Physical examination was remarkable for sclera icterus, right upper quadrant abdominal tenderness and jaundice. Her LFTs peaked at AST of 449 U/L, ALT of 745 U/L, ALP of 1045 U/L, total bilirubin of 11.6 mg/dL with direct bilirubin of 2.4 mg/dL, and GGT of 620 U/L. Negative work up included HAV, HBV, HCV, ANA, AMA, ASMA, ANCA, LKM, CMV IgM, EBV IgM, and HIV. APAP, Salicylate, CA 19-9 and CEA levels were within normal range. Abdominal ultrasound was unremarkable. CT and MRI abdomen were remarkable for mild splenomegaly. Patient was started on Vancomycin and Zosyn due to her septic picture, but symptoms did not improve. After few days blood cultures started growing Histoplasmosis Capsulatum, the histoplasma antigen was positive as well. Patient was started on Amophotericin B and Voriconazole and discharged home on Itraconzaole. Follow up appointment 2 months later showed improved LFTs and significant improvement in symptoms, with resolution of her jaundice. Disseminated histoplasmosis in our patient presented with hepatocellular jaundice and was diagnosed with acute hepatitis. Early diagnosis of disseminated histoplasmosis should be made by histoplasma antigen detection in urine and serum. In severe cases, Amphotericin B should be used initially and then it could be switched to Itraconazole due to the more desirable side effect profile. Once symptoms resolve and antigen levels return to normal, treatment can be discontinued. Prospective studies are needed to accurately assess the risk of fungal infections presenting like hepatitis in immunocompromised patients. Hence, clinicians should have a high index of suspicion for disseminated histoplasmosis in immunocompromised patients.

Antigen Detection in the Diagnosis of Histoplasmosis: A Meta-analysis of Diagnostic Performance.

We performed a meta-analysis of diagnostic data to evaluate the performance of Histoplasma antigen detection tests for diagnosing histoplasmosis. We included all studies involving human subjects that assessed the performance of any antigen detection test for histoplasmosis in urine or serum by carrying out an exhaustive and reproducible search of the literature between 1980 and 2014 from four databases. Quality of the articles was assessed, and meta-analysis was performed under the random effects model, calculating sensitivity, specificity, likelihood and odds ratios, and ROC curve using Meta-DiSc(es). Nine out of a total of 23 studies met strict quality criteria and were therefore included. The overall sensitivity for antigen detection in serum and urine was 81% (95% CI 78-83%), while specificity was 99% (95% CI 98-99%). Sensitivity for antigenuria and antigenemia was 79% (95% CI 76-82%) and 82% (95% CI 79-85%), respectively; specificity values were 99% (95% CI 98-100%) in urine and 97% (95% CI 96-98%) in serum. The positive and negative likelihood ratios were 49.5 (95% CI 20.7-118.7) and 0.19 (95% CI 0.14-0.26), respectively, while the diagnostic OR was 362 (95% CI 121.2-1080.3) and area under the curve was 0.99. In conclusion, the performance of Histoplasma antigen detection assay of urine was not significantly different from that of blood, indicating that antigenuria and antigenemia have equal diagnostic value in histoplasmosis.

Sensitivity and Specificity of Histoplasma Antigen Detection by Enzyme Immunoassay.

The objective of this study was to evaluate the sensitivity and specificity of an antigen enzyme immunoassay (EIA) on urine samples for the diagnosis of histoplasmosis in dogs. This retrospective medical records review included canine cases with urine samples submitted for Histoplasma EIA antigen assay between 2007 and 2011 from three veterinary institutions. Cases for which urine samples were submitted for Histoplasma antigen testing were reviewed and compared to the gold standard of finding Histoplasma organisms or an alternative diagnosis on cytology or histopathology. Sensitivity, specificity, negative predictive value, positive predictive value, and the kappa coefficient and associated confidence interval were calculated for the EIA-based Histoplasma antigen assay. Sixty cases met the inclusion criteria. Seventeen cases were considered true positives based on identification of the organism, and 41 cases were considered true negatives with an alternative definitive diagnosis. Two cases were considered false negatives, and there were no false positives. Sensitivity was 89.47% and the negative predictive value was 95.35%. Specificity and the positive predictive value were both 100%. The kappa coefficient was 0.9207 (95% confidence interval, 0.8131-1). The Histoplasma antigen EIA test demonstrated high specificity and sensitivity for the diagnosis of histoplasmosis in dogs.

Histoplasmosis: An emerging infection

Histoplasmosis is commonly found in US and central America; recently cases were diagnosed from Kerala also. The causative organism Histoplasma capsulatum is found abundant in soil mixed with bird or bat guano. Infection occurs by the inhalation of small oval conidia which can enter the terminal bronchioles and then the alveolar spaces. They multiply inside the macrophages and the cellular immune system of the host decides the outcome. Usually it is a self limiting pulmonary infection, but it can vary from mild pneumonitis to severe acute respiratory distress syndrome. If primary manifestation progresses, disseminated histoplasmosis involving liver, spleen, bone marrow, adrenal gland and mucocutaneous membranes result. Skin test antigen is used in epidemiological studies to find the true extent of infection. Rapid diagnosis is possible with histoplasma antigen detection but serology is useful only in certain cases. Histopathology aids the diagnosis a lot. But the fungal culture remains the gold standard for the confirmation. Histoplasmosis is successfully treated with azoles if it is a mild infection and if severe liposomal Amphotericin B is used initially and then switched over to Itraconazole to be continued for several months.

Evaluation of Commercially Available Reagents for Diagnosis of Histoplasmosis Infection in Immunocompromised Patients

Urinary histoplasma antigen measurement can be useful for diagnosing systemic histoplasmosis and for monitoring treatment response, especially in immunocompromised patients. However, testing has traditionally been limited to specialized reference laboratories, as immunoassay reagents for the antigen were not widely available. Recently, a polyclonal-antibody-based in vitro diagnostic (IVD) kit for histoplasma antigen detection was released, as well as monoclonal-antibody reagents against the target. We evaluated the analytical and clinical performance of the two reagents. Both assays were capable of detecting histoplasma antigen in urine samples over a wide dynamic range, although the monoclonal assay showed improved precision and analytical sensitivity relative to the polyclonal IVD. In a test set of clinically characterized patient samples, the monoclonal laboratory-developed test (LDT) demonstrated 90.5% sensitivity and 96.3% specificity versus 61.9% sensitivity and 79.3% specificity for the polyclonal IVD, with areas under the curve (AUCs) of 0.987 and 0.754, respectively. The major differences between the two assays were higher background reactivity in healthy donors with the polyclonal assay and an increased signal response in positive samples for the monoclonal assay. The impact of these differences on monitoring treatment response was evaluated in a series of patients undergoing treatment for histoplasmosis. While all the assays gave similar qualitative estimates of treatment response, responses were more evident using the monoclonal assay. In summary, we conclude that while multiple assays are available for measuring histoplasma antigen in urine, a monoclonal-antibody-based assay appears to provide improved analytical performance for management of immunocompromised histoplasmosis patients.

Histoplasmosis After Solid Organ Transplant

To improve our understanding of risk factors, management, diagnosis, and outcomes associated with histoplasmosis after solid organ transplant (SOT), we report a large series of histoplasmosis occurring after SOT. All cases of histoplasmosis in SOT recipients diagnosed between 1 January 2003 and 31 December 2010 at 24 institutions were identified. Demographic, clinical, and laboratory data were collected. One hundred fifty-two cases were identified: kidney (51%), liver (16%), kidney/pancreas (14%), heart (9%), lung (5%), pancreas (2%), and other (2%). The median time from transplant to diagnosis was 27 months, but 34% were diagnosed in the first year after transplant. Twenty-eight percent of patients had severe disease (requiring intensive care unit admission); 81% had disseminated disease. Urine Histoplasma antigen detection was the most sensitive diagnostic method, positive in 132 of 142 patients (93%). An amphotericin formulation was administered initially to 73% of patients for a median duration of 2 weeks; step-down therapy with an azole was continued for a median duration of 12 months. Ten percent of patients died due to histoplasmosis with 72% of deaths occurring in the first month after diagnosis; older age and severe disease were risk factors for death from histoplasmosis. Relapse occurred in 6% of patients. Although late cases occur, the first year after SOT is the period of highest risk for histoplasmosis. In patients who survive the first month after diagnosis, treatment with an amphotericin formulation followed by an azole for 12 months is usually successful, with only rare relapse.