Histoplasma Capsulatum Research Articles (Page 1)

Histoplasma capsulatum is a dimorphic fungus endemic to the Ohio and Mississippi River valleys. Although pulmonary involvement is most common, rare extrapulmonary manifestations such as laryngeal histoplasmosis can mimic malignancy and pose diagnostic challenges, particularly in immunosuppressed individuals residing outside endemic areas. We describe a 40-year-old immunosuppressed male on tumor necrosis factor-alpha (TNF-α) inhibitor therapy who presented with progressive dysphagia, hoarseness, and weight loss. Laryngoscopy revealed verrucous supraglottic lesions concerning for malignancy. Imaging further raised suspicion for neoplastic or granulomatous disease. However, biopsy revealed H. capsulatum and confirmed with fungal staining. The patient failed initial treatment with oral itraconazole and required escalation to intravenous amphotericin B, followed by long-term oral antifungal therapy. Discontinuation of infliximab and close multidisciplinary follow-up led to full clinical resolution. This case highlights the importance of considering histoplasmosis in the differential diagnosis of laryngeal lesions, even in non-endemic regions and HIV-negative patients. Immunomodulatory therapies such as TNF-α inhibitors increase susceptibility to disseminated fungal infections. Early biopsy, appropriate fungal staining, and prompt antifungal therapy are critical for accurate diagnosis and successful treatment of this rare but serious presentation.

Disclosure: K. Khoshbin: None. K. Lane: None. S.S. Kim: None.With the increasing use of medical imaging, bilateral adrenal masses are identified more frequently. The clinical context significantly influences the likelihood of the underlying etiology found. Hypercalcemia can arise from various causes and may be an important diagnostic clue. We present the case of a 77-year-old man with no prior history of malignancy or known immune-compromising condition who was admitted to the hospital with progressive dyspnea, weight loss (40 lbs), and poor appetite over the last 4 months. Initial laboratory evaluation revealed hypercalcemia with a corrected calcium level of 12.1 mg/dL (normal range: 8.6-10.4 mg/dL) and acute kidney injury (AKI). An ultrasound performed during the workup for AKI identified bilateral adrenal masses. An MRI demonstrated large, bilateral heterogeneous masses, measuring up to 6 cm in craniocaudal dimension. The top differential diagnoses included metastases and pheochromocytomas. Biochemical workup revealed a normal 25-hydroxy vitamin D, a suppressed parathyroid hormone (PTH) level of 12 pg/mL (normal range: 11-51 pg/mL), elevated 1,25-dihydroxy vitamin D at 103 pg/mL (normal range: 19.9-79.3 pg/mL), and mildly elevated PTH-related peptide at 2.4 pmol/L (normal range: 0-2.3 pmol/L). Serum and urine metanephrines and normetanephrines were normal, as were cortisol, ACTH, renin, and aldosterone levels, ruling out pheochromocytoma and primary hyperaldosteronism. A CT scan of the chest revealed bilateral apical fibronodular scarring consistent with prior granulomatous disease, even though the patient had no known prior diagnosis. A PET scan demonstrated intensely FDG-avid, peripherally enhancing bilateral adrenal masses without evidence of an extra-adrenal primary neoplastic process. Flow cytometry excluded leukemia and lymphoma. Infectious disease testing, including endemic mycoses and tuberculosis, was initiated. Following the exclusion of pheochromocytoma, an adrenal biopsy was performed. Both the biopsy and serological studies confirmed Histoplasma capsulatum as the underlying cause. Isavuconazole was commenced for treatment. The patient had spent significant time in Chicago in his 20s, which might have been associated with Histoplasma capsulatum infection. Hypercalcemia was initially managed by intravenous fluids and denosumab but ultimately resolved 1 week after isavuconazole was started. This case highlights the importance of considering infectious diseases in the differential diagnosis of bilateral adrenal masses. It also underscores the diagnostic interplay between hypercalcemia and adrenal pathology, where both malignancy and infectious etiologies can present with overlapping features. Early identification and targeted investigations are crucial to distinguish between these conditions, ensuring timely and appropriate management.Presentation: Sunday, July 13, 2025

Abstract Background and Aims Disseminated histoplasmosis (DH) is a common opportunistic infection caused by Histoplasma capsulatum in people living with HIV/AIDS (PLWHA) in endemic areas, causing 5%–15% of AIDS-related deaths. HIV infection is associated with acute kidney injury (AKI) due to drug nephrotoxicity, HIV-associated nephropathy, and deposition of immune complexes. Black race, family history of nephropathy, low CD4+ T lymphocyte (CD4) count, high viral load (VL), Hepatitis B and C, advanced age, and smoking increase this risk. Common causes of AKI in PLWHA are prerenal causes, acute tubular necrosis, and drug nephrotoxicity. São José Hospital for Infectious Diseases (HSJ) is a reference hospital in Fortaleza, the capital of the state of Ceará, in northeastern Brazil, an endemic region of DH. This study aims to describe the prevalence of AKI and associated factors in PLWHA with DH. Method This retrospective observational study evaluated clinical, epidemiological, and laboratory aspects in PLWHA with DH at HSJ from March 2023 to May 2024. Inclusion criteria were PLWHA aged 18 years or older with DH, excluding those with chronic kidney disease (CKD). AKI and CKD definitions followed Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Categorical variables were presented as counts and relative frequencies in percentages. Chi-square tests were used to assess the association between categorical variables. Continuous variables were first evaluated for normality using the Shapiro-Wilk test and by analyzing Q-Q plots, histograms, and dispersion measures. Variables considered normally distributed were presented as mean ± standard deviation, while non-normally distributed variables were reported as median and interquartile range. Student's t-test was used for normally distributed data, and the Mann-Whitney test for non-normally distributed data, with a significance level of P < 0.05. The analysis was conducted using R software (v4.3.1; R Core Team, 2021). The study was approved by the Human Research Ethics Committee of HSJ (Process Number 60380022.0.0000.5044). Results Sixty-one patients were initially included in the study, but three with pre-existing CKD were excluded. Among the 58 remaining patients, the average age was 40.4 + 11.3 yrs, with 79.3% being men. During hospitalization, 89.7% progressed to AKI, categorized as follows: 19.0% to Stage 1, 29.3% to Stage 2, and 41.4% to Stage 3. No statistically significant differences were found in demographics or comorbidities between the non-AKI group (NAG) and the AKI group (AG). However, patients in the NAG used antiretroviral therapy more frequently (P = 0.003). Patients in the AG had higher HIV VL (P = 0.018), while there was no difference in CD4 count between the two groups. The AG presented with more respiratory symptoms (P = 0.009) and hepatomegaly (P = 0.04) and had higher rates of diagnoses via direct microscopy in the buffy coat (BC) (P = 0.029) and peripheral blood (P = 0.016), and BC culture (P = 0.006), indicating a likely higher fungal load. Additionally, the AG exhibited more thrombocytopenia (P = 0.04), uremia (P = 0.01), elevated alanine aminotransferase (P = 0.007) and aspartate aminotransferase (P < 0.001), hypertriglyceridemia (P = 0.028), hyperbilirubinemia (P = 0.012) and increased lactate dehydrogenase (P < 0.001). They received more days of amphotericin B (AmB) lipid complex treatment (P = 0.007). Among the patients, 25.1% died, all from the AG, with 5.9% in stage 2 and 54.2% in stage 3. Conclusion The high prevalence of AKI in PLWHA with DH is concerning. It is crucial to identify laboratory abnormalities indicating tissue damage and their association with AKI progression. The elevated mortality in the Stage 3 subgroup underscores the need for early diagnosis, avoidance of nephrotoxic drugs, and treatment with lipid formulations of AmB, which can improve outcomes.

The review of the current microbiological, epidemiological and diagnostic aspects of some endemic mycoses (histoplasmosis, blastomycosis, emergomycosis) found on the African continent is brought forward. Other endemic mycoses (coccidioidomycosis, paracoccidioidomycosis, talaromycosis) have not been described in Africa and can only be imported. Histoplasmosis caused by Histoplasma capsulatum var. capsulatum is widespread in the world, but Africa is the only continent where two variants coexist – H. capsulatum and H. duboisii. The latter is the causative agent of the disease called “african histoplasmosis”. Disseminated forms of histoplasmosis are diagnosed in 5–20 % of HIV-infected individuals. African cases of blastomycosis are caused predominantly by Blastomyces percursus and B. emzantsi species, which differ significantly from the etiologic agents of this disease in North America (B. dermatitidis and B. gilchristii). The number of diagnosed cases of endemic mycoses in Africa has increased significantly in the last decade, which may be due to a new disease, emergomycosis. One of the etiologic agents of this mycosis is the dimorphic fungus Emergomyces africanus. Laboratory diagnostics of endemic mycoses in most African countries is limited due to the lack of experienced personnel and advanced test systems.

Abstract Objectives Histoplasmosis is a lung and blood disease caused by a dimorphic fungus, Histoplasma capsulatum, which causes non-specific clinical manifestations making differential diagnosis aimed at its detection difficult. Case presentation We explore the case of a 28-year-old man whose blood test revealed pancytopenia, which led to review of the blood film, which showed yeast-like cytoplasmic inclusions in some of the neutrophils, suggestive of H. capsulatum infection. Given the suspicion, the laboratory expanded tests for the detection of fungal biomarkers such as galactomannan antigen and B-D-glucan, in addition to HIV serology, which were positive. Conclusions This case highlights the importance of the morphological review of the blood film in the laboratory, as it provides very valuable and relevant information for the diagnosis of many diseases. As well as the importance of communication between the different departments in the laboratory.

Introduction: Disseminated Histoplasmosis (DH) is a clinical subtype of Histoplasmosis, a disease with a worldwide distribution and strong presence in the Americas region. Objective: Describe four cases of HD in workers. Method: A retrospective and descriptive case series study was conducted on patients attended at a specialized teaching hospital for infectious diseases located in the Northeast region of Brazil. Results: Four cases of histoplasmosis, their clinical, laboratory manifestations, and evolution were analyzed. All the situations described were related to the DH subtype, a pathology with reserved prognosis and whose accurate diagnosis is still challenging. The four cases involved patients with AIDS. Conclusions: Coinfection between AIDS (HIV) and Histoplasma capsulatum was present in 100% of the sample; one of the cases was a triple coinfection between Histoplasma capsulatum, AIDS, and SARS-CoV-2. DH was a potentially fatal entity, with a progression to death in 100% of the described situations.

When local epidemiology of endemic fungal infections is poorly understood, it is difficult to determine the clinical impact of screening for these pathogens in people living with HIV. We found no Histoplasma urine antigen or serum antibody in over 450 symptomatic patients with a new diagnosis of HIV in Port-au-Prince, Haiti. These findings indicate that systematic testing is likely to be low yield in Port-au-Prince, although it is well described in other countries in the region, and may have higher prevalence in rural areas. These findings are relevant to other settings where the prevalence of histoplasmosis is poorly defined, as similar studies could also inform local evidence-based guidelines.

Histoplasmosis is a systemic fungal infection caused by Histoplasma capsulatum, a dimorphic fungus acquired through inhalation of spores from soil contaminated with bird or bat droppings. While often asymptomatic or mild in immunocompetent individuals, it may progress to disseminated histoplasmosis in patients with compromised cell-mediated immunity, including those with acquired immunodeficiency syndrome, on immunosuppressive therapy, or with hematologic malignancies. Clinical features include fatigue, mucocutaneous lesions, oral ulcers, lymphadenopathy, and bone marrow involvement. We report a rare case of disseminated histoplasmosis in a 44-year-old human immunodeficiency virus-negative male from North Bengal—a non-endemic region. The disease primarily involved mesenteric and retroperitoneal lymph nodes and was initially misdiagnosed as metastatic carcinoma on cytological and radiological assessment. To our knowledge, this is the first documented case of disseminated histoplasmosis from this region. This case highlights the need for increased clinical awareness and consideration of histoplasmosis in the differential diagnosis of lymphadenopathy, even in immunocompetent individuals from non-endemic areas.

The filamentous fungus Aspergillus fumigatus is equipped with an efficient zinc uptake system that allows this fungus to survive and grow within the very zinc-limiting environment provided by the lungs of immunosuppressed patients. To deal with zinc scarcity, A. fumigatus deploys a homeostatic and adaptive response that enables it to scavenge for and uptake zinc from host tissues. Finally, zinc ions are distributed intracellularly and lodged in fungal proteins that require them for normal functioning. It is believed that most zinc-requiring proteins acquire zinc ions to become properly metalated by competition with cellular zinc proteins. However, certain zinc proteins may exhibit inherent thermodynamic and/or physicochemical properties that hamper them from competing for zinc with other proteins during zinc deficiency, such that they can only be properly metalated if aided by specific metallochaperones. In this study, we report a comprehensive approach to the role of the zinc metallochaperones of A. fumigatus (MchA, MchB, and MchC) on both fungal physiology during zinc deficiency and fungal pathogenesis. Our data suggest that MchA might play a role in supplying zinc to one or more proteins operating in a biosynthetic pathway that use tetrahydrofolate (THF) as a cofactor; MchB is required for reactive oxygen species (ROS) production as an adaptive response to zinc deficiency, whereas MchC plays a role in THF biosynthesis, most likely by supplying zinc to GTP cyclohydrolase I. This is the first study that provides insights into the role of zinc-metallochaperones in a fungal pathogen and how they could be exploited as antifungal targets.IMPORTANCEAspergillus fumigatus is able to suppress nutritional immunity and obtain zinc from the lungs of immunosuppressed patients, allowing it to grow and cause invasive pulmonary aspergillosis. To combat this lethal infection, there is an urgent need for new antifungals. In this regard, tetrahydrofolate (THF) biosynthesis is a promising target. However, antifungal drugs against this process have not been developed yet, likely because only a few antifolates used as antibacterials are also active against a limited number of fungal pathogens. Our research may provide the explanation of the sensitivity to antifolates of those pathogens (Pneumocystis jirovecii, Paracoccidioides brasiliensis, and Histoplasma capsulatum), being that all lack MchC-like proteins. Moreover, we foresee that inhibition of THF biosynthesis in MchC-bearing fungal pathogens could be enhanced by inhibiting MchC activity. Also, our findings suggest the notion that ROS overproduction typically occurring in all cells during zinc deficiency may rely on proper metalation of certain zinc-dependent proteins.

Disseminated histoplasmosis in erythematosus systemic lupus: A case report and review.

Histoplasma capsulatum is a human fungal pathogen that survives and proliferates within phagocytic immune cells. To sustain growth in the nutrient-limited phagosome environment, the pathogenic yeast scavenges available carbon sources, which must be metabolized through central carbon metabolism for respiration and biomass synthesis. However, Histoplasma carbon metabolic pathways operating in the pathogenic yeast phase have not been extensively mapped. To address this gap, we employed a fluxomic platform using stable isotope tracers to quantify the cellular reaction rates of central carbon metabolism. This approach revealed that, in Histoplasma yeasts, carbon resides within five main reservoirs: fatty acids, proteins, mannitol, nucleic acids, and cell wall components. Carbon conversion efficiency, or biomass yield, was approximately 50%, indicating substantial CO2 loss from supplemented carbon substrates, glucose, and glutamate. 13C-labeling analysis demonstrated simultaneous glycolysis and gluconeogenesis, and enriched serine labeling confirmed threonine aldolase activity in serine biosynthesis. Compartmentalization of pyruvate metabolism was evident from the labeling of amino acids derived from pyruvate, with the methylcitrate cycle identified as the primary source of labeled pyruvate. Notably, malic enzyme and pyruvate carboxylase exhibited negligible fluxes, while mitochondrial reactions, particularly CO2-producing ones, were the most active. These results offer insight into key metabolic reactions, alternative pathways, and metabolite/enzyme compartmentalization in Histoplasma yeast metabolism. This foundational framework supports future studies aimed at identifying metabolic targets for novel histoplasmosis therapeutics.IMPORTANCETo our knowledge, this study represents the first application of 13C-metabolic flux analysis to a human fungal pathogen, where we identified carbon reservoirs and quantified the metabolic fluxes of pathogenic Histoplasma yeasts. Our findings demonstrated that Histoplasma metabolizes carbon toward cellular respiration to robustly produce CO2 and energy but also uses alternative pathways within central metabolism for biosynthesis. Given the potential for other pathogenic fungi to share similar metabolic features, especially biomass, our study offers a comprehensive framework for deciphering fungal metabolism, providing insights into their infection-enabling metabolism and offering a foundation for identifying new therapeutic targets.

A 56-year old immuno-competent male from a non-endemic region in India presented with progressive weight loss, hoarseness of voice and widespread cutaneous lesions, including leonine facies, genital nodules and diffuse scaling. Magnetic resonance imaging of the neck revealed oedematous thickening of the false vocal cords, epiglottis and aryepiglottic folds, suggesting laryngeal involvement. All routine investigations were normal. Urine Histoplasma antigen levels were markedly elevated. Skin biopsy revealed granulomatous inflammation with intracellular yeast-like organisms, and polymerase chain reaction confirmed Histoplasma capsulatum DNA. A diagnosis of disseminated histoplasmosis with probable laryngeal involvement was made. The patient responded well to liposomal amphotericin B followed by itraconazole for 12 months. Although histoplasmosis commonly affects immunocompromised individuals, its rising incidence in immuno-competent patients from non-endemic regions necessitates greater clinical vigilance and emphasises the role of dermatological assessment and targeted fungal testing in systemic mycoses.

The aim of this study was to investigate Histoplasma seroprevalence and associated risk factors in free-roaming cats from 2 endemic regions: north central Oklahoma and eastern Tennessee. Seroprevalence was determined using frozen serum samples from trap, neuter, release programs in Tennessee (n = 426) and Oklahoma (200) from 2013 to 2024. For Tennessee samples, those with complete signalment information were included. For Oklahoma samples, no demographic information was available. An anti-Histoplasma immunoglobulin G antibody enzyme immunoassay was used to evaluate for the presence of anti-Histoplasma immunoglobulin G, and results were categorized as positive, intermediate, or negative. The Fisher exact test was used to assess risk factor associations. In total, 51 of 626 (8.1%) tested positive or intermediate, and 575 of 626 (91.9%) were negative. Of the samples from Tennessee, 24 of 403 (6.0%) were seropositive. From Oklahoma, 4 of 200 (2.0%) were seropositive. Of 47 Tennessee samples with positive or intermediate results, the median was 10.3 ELISA units/mL (EU; range, 8 to 31.1; positive, ≥ 10.0 EU), and of 4 Oklahoma samples with positive or intermediate results, the median was 20.3 EU (range, 18.8 to 22.6). There was no association between retrovirus infection, sex, pregnancy status, or presence of injury/disease and Histoplasma seropositivity. Our study is the first to document seropositivity of this regionally endemic fungus in free-roaming cats. Additional studies are encouraged to evaluate if similar seroprevalence is seen in indoor cats and if seropositivity is associated with clinical infection. Given the reported seroprevalence of histoplasmosis in felines, continued monitoring for Histoplasma infection by veterinary practitioners is warranted.

BackgroundHistoplasma capsulatum is a globally distributed dimorphic fungal pathogen endemic to the Americas, Africa, and Asia. It causes histoplasmosis, a disease acquired via inhalation of spores from contaminated environments. It thrives in nitrogen-rich soils and is disseminated by avian and chiropteran reservoirs. Histoplasma capsulatum has been found in wild mammals such as rodents, marsupials, felines, and xenarthrans, suggesting diverse reservoirs that may influence its maintenance and transmission in endemic areas. This study aimed to detect H. capsulatum in tissues of wild small mammals sampled across Ecuador.MethodsTissue samples (n = 324) were collected from wild mammals across the Coast, Andean, and Amazon regions between 2022 and 2023. Species were identified morphologically and H. capsulatum was detected using nested PCR targeting the 100-kDa protein-encoding gene. Positive samples were sequenced and analyzed. Ecological niche modeling focused on environmental clustering, via one class support vector machine (OC-SVM) hypervolumes, identified regions suitable for fungal survival.ResultsH. capsulatum was detected in 14% of samples in 30 of 106 species studied, predominantly in Chiroptera (80%) followed by Rodentia (15%) and Didelphimorphia (4%). Suitable environmental conditions were concentrated in Ecuador’s Coast region with isolated patches in the Andean and Amazon regions.ConclusionThis study documents the broad host range and ecological distribution of H. capsulatum in Ecuador, reinforcing concerns about its zoonotic potential. The detection of the fungus across diverse mammalian taxa and ecosystems emphasizes the importance of wildlife-based surveillance to better understand fungal pathogen reservoirs and geographic hotspots.

Histoplasma capsulatum var capsulatum is an endemic respiratory pathogen presenting in various forms including miliary histoplasmosis, acute and chronic pulmonary histoplasmosis, and acute or subacute disseminated disease. The differential diagnosis of chronic pulmonary histoplasmosis (CPH) is broad, encompassing bacterial, fungal and malignant aetiologies. PubMed was searched for relevant articles on the radiological characteristics of CPH and the most common differential diagnoses of tuberculosis and chronic pulmonary aspergillosis. The Fleischner Society Glossary of Terms for Thoracic Imaging was used to analyze the features. The contribution of culture, antibody and antigen and PCR to the diagnosis of CPH is summarized. Cavitation and pulmonary nodules are the most common features of CPH. Pleural effusion, pleural thickening, intrathoracic lymphadenopathy and bronchiectasis are not characteristic of CPH; uncommonly CPH can be complicated by an aspergilloma. Data on the radiologic features of CPH are derived primarily from the USA, Brazil, and China. CPH can be diagnosed by respiratory fungal culture (using extended culture times) or Histoplasma PCR (although data are scarce) and serum Histoplasma antigen and antibody. Data on bronchoscopy sampling for antigen are lacking. In patients with pulmonary cavitation without a confirmed diagnosis of tuberculosis or aspergillosis should be evaluated for CPH.

Diseases caused by microscopic fungi (mycoses) have become an important clinical problem in recent decades. The importance of mycoses in rheumatology has increased significantly due to the active introduction of genetically engineered biological drugs into clinical practice, primarily tumor necrosis factor-α inhibitors and interleukin-17 inhibitors. In addition, a number of questions arise when establishing timely and correct diagnosis, as well as prescribing rational therapy in patients with mycotic septic arthritis, a disease that is quite difficult to treat. The most common etiological agents of fungal arthritis (FA) include Candida spp., Aspergillus fumigatus, Sporothrix schenckii, Coccidioides immitis, Blastomyces dermatitis, Cryptococcus neoformans, and Histoplasma capsulatum. This review examines the problems of diagnosis and treatment of FA associated with these pathogens.

Histoplasmosis, the disease caused by thermally dimorphic fungi in the genus Histoplasma, is usually associated with pulmonary involvement in healthy individuals and a disseminated syndrome in immunocompromised patients. Among African patients, lung disease is less commonly reported than skin, lymph node, or bone disease. Because different species or strains may be associated with different disease presentations and outcomes, understanding genetic and phenotypic variation in the genus Histoplasma is important for accurate diagnosis and treatment. We sequenced the genomes of 36 Histoplasma isolates from Africa and used population genomics to measure the genetic variation of the genus on the African continent and to compare the genetic diversity of these isolates to the previously described Indian and American phylogenetic species. We found that strains from Africa belong to genetic lineages that are differentiated enough to be considered a phylogenetic species. The first, the Africa lineage, is consistent with a previously described species (Histoplasma capsulatum duboisii) which includes clinical cases more frequently associated with extrapulmonary manifestations than cases caused by other lineages. While there is some evidence of gene flow between Histoplasma lineages, it has not precluded divergence. A second lineage corresponding to Histoplasma capsulatum farciminosum (Hcf) includes all the isolates from equine samples. We identified loci under selection in these two better-sampled lineages and found loci that have undergone parallel positive selection. A single African isolate resembles a South American lineage. Finally, we measured the potential range expansion of the disease using climatic projections, highlighting the need to implement surveillance to monitor phylogenetic species of Histoplasma across Africa.IMPORTANCEHistoplasma fungi, which cause histoplasmosis, are widespread and considered high-priority pathogens. While researchers have identified multiple genetically distinct lineages worldwide, little is known about Histoplasma diversity in Africa due to minimal sampling and inadequate diagnostics. Our study addresses this gap using population genomics to analyze stored African isolates. We identified three distinct groups: one of them is endemic to Africa and aligns with Histoplasma capsulatum duboisii, a lineage linked to skin-involved infections, while another lineage (Hcf) matches Histoplasma capsulatum farciminosum, associated with equine lymphangitis. Additionally, one African isolate closely resembles a South American lineage (mz5-like). These three lineages are genetically unique enough to be considered separate species. By integrating phylogenetics, clinical data, and environmental modeling, we provide the most comprehensive genetic assessment of African Histoplasma to date. This work not only enhances our understanding of an overlooked pathogen but also offers a model for studying other neglected fungi with global health implications.

Multiple pathogens can infect the canine reproductive and central nervous systems, including organisms that are zoonotic, such as Brucella canis, pathogenic Leptospira spp., Anaplasma phagocytophilum, Histoplasma capsulatum, and Blastomyces dermatitidis. In this study, we developed a targeted next-generation sequencing (tNGS) panel to identify common infectious agents related to neurologic and reproductive disease in canines while incorporating less common zoonotic agents into a single test. Primer pools were developed to detect 34 pathogens and used in two multiplex PCR assays, which were combined prior to library preparation and sequencing using Ion Torrent technology. A feasibility study was performed with known positive clinical samples, bacterial isolates, or synthetic DNA (gBlocks) spiked into nucleic acids from negative canine clinical samples. Of the 34 organisms included in the panel, 33 were detectable. Some primer sets were not specific for the intended target organism, based on BLAST analysis (NCBI) of the obtained sequences. Compared to real-time PCR assays, pathogens could be detected at Ct values from 33-38, depending on the pathogen, and at approximately 100-1000 copies based on gBlock testing. A total of 76 samples (39 positive and 40 negative) were tested, representing neurological and reproductive samples. Diagnostic sensitivity and specificity for the assay were calculated as 89% and 98%, respectively. The tNGS assay had the added benefit of strain-typing Canine distemper virus and Canine parvovirus-2 in the positive samples. For reproducibility, a blinded panel was tested by our laboratory and another laboratory using the same tNGS protocol where the assay had an agreement for 16 out of 18 samples with a Cohen's kappa value of 0.77, indicating high reproducibility. The tNGS assay was not as sensitive as real-time PCR assays, which is a known limitation of this method, and was evident based on the diagnostic sensitivity testing. However, the comprehensive nature of this assay is beneficial for syndromic testing.

Darling's disease, another name for oral histoplasmosis, is an uncommon but important form of Histoplasma capsulatum infection that can appear as oral cavity lesions that frequently mimic cancers like squamous cell carcinoma. Immunocompromised people, notably those with HIV, are most vulnerable to this fungal infection, while immunocompetent patients can still get it. Because of their appearance and chronic nature, the clinical presentation usually consists of painful, ulcerative lesions that could be mistakenly diagnosed as cancer. In the uncommon instance described in this analysis, an 80-years-old man who had no known addictions or comorbidities showed up with a non-bleeding ulcero-proliferative lesion on his tongue that had been there for two months. The lesion was eventually determined to be oral histoplasmosis after being misdiagnosed as mouth cancer. The diagnostic difficulties associated with this illness were highlighted by the histopathological investigation, which showed granulomatous inflammation and the distinctive yeast forms of Histoplasma. Inappropriate treatment plans and delays in efficient management can result from misdiagnosis. This example emphasizes how crucial it is to take oral histoplasmosis into account when making a differential diagnosis for oral lesions, especially in areas where it is endemic. To get positive results and avoid consequences from misdiagnosis, early detection and adequate antifungal medication are essential.

Considering the need for a rapid, sensitive, and specific test for the early diagnosis of cryptococcal meningitis in critical regions where lumbar puncture and culture are inaccessible, we analyzed the specificity of the Lateral Flow Assay (LFA) for cryptococcal antigen in 217 serum specimens. Group 1: 68 Human Immunodeficiency Virus (HIV)-uninfected patients with paracoccidioidomycosis, histoplasmosis, aspergillosis, trichosporonosis, and tuberculosis; Group 2: 149 patients with HIV infection, including seven with histoplasmosis, and one with aspergillosis, and Group 3 with 24 proven cryptococcosis patients. Cross-reactivity of cryptococcal mannans and polysaccharides secreted by Paracoccidioides brasiliensis, Histoplasma capsulatum, and Trichosporon spp. has been described in vitro. However, only a few cases of positive LFA tests in aspergillosis, trichosporonosis, candidemia, and bacterial infections sera have been reported. We observed false-positive LFA in 2/29 aspergillosis specimens but not in other mycoses or tuberculosis. Among 149 HIV-infected patients, three specimens tested positive, two had cytomegalovirus infections, one of whom also had toxoplasmosis and the other, Kaposi´s sarcoma; one patient had no opportunistic infections. We observed sensitivities of 0.933 (serum), 0.95 (cerebrospinal fluid [CSF]), and 1.0 (serum or CSF) for LFA, and for all negative controls (N=217, serum), a specificity of 0.977, and a negative predictive value (NPV) of 0.938. The specificity and NPV were 0.964 and 0.791, respectively, for 55 patients with mycoses; and 0.98 and 0.912 for 149 HIV-infected patients. We confirmed LFA's high specificity and accuracy for the control groups. There were 6.89% of false-positive results for aspergillosis, and no false-positive results for paracoccidioidomycosis, histoplasmosis, tuberculosis, or other bacterial diseases.