Histoplasmosis pulmonar cavitada en un paciente pediátrico: reporte de caso / Acute cavitated pulmonary histoplasmosis in a pediatric patient: a case report

La histoplasmosis es una micosis producida por el Histoplasma capsulatum. Esta condición es endémica en Estados Unidos, Suramérica, América central y África. Suele presentarse en todas las edades, pero en niños; en especial en aquellos inmunodeprimidos, se han descrito presentaciones graves o atípicas. Se presenta el caso de un paciente de 16 años con antecedentes de trasplante renal, que inicia con síntomas respiratorios inespecíficos, tos y alzas térmicas intermitentes. La radiografía de tórax mostró una imagen de condensación cavitada en el lóbulo superior izquierdo, por lo que se realiza una fibrobroncoscopia, lavado broncoalveolar y cultivos para patógenos habituales, micobacterias y hongos, lográndose aislar al Histoplasma capsulatum. EL objetivo de este trabajo es el de resaltar la consideración de histoplasmosis como diagnóstico diferencial de lesiones cavitadas en parénquima pulmonar en pacientes inmunodeprimidos con la presentación de un caso clínico.

Histoplasmosis is a mycosis caused by Histoplasma capsulatum. This condition is endemic in the United States, South America, Central America, and Africa. It usually occurs in all ages, but in children, especially those immunosuppressed, serious or atypical presentations have been described. We present the case of a 16-year-old patient with a history of kidney transplantation that began with nonspecific respiratory symptoms, cough, and intermittent fever peaks. Imaging findings suggestive of cavitation were found, which by means of a fiberoptic bronchoscopy and bronchoalveolar lavage study isolated Histoplasma capsulatum by means of a deep mycosis culture. The main interest of the case presented is the consideration of histoplasmosis in the presence of cavitated lesions in the lung parenchyma in immunosuppressed patients.

Thermotolerance of Histoplasma capsulatum at 40 °C predominates among clinical isolates from different Latin American regions

ABSTRACT The yeast phase of 22 Histoplasma capsulatum clinical isolates from Mexico, Argentina, Colombia, and Guatemala and three reference strains, one from Panama and two from the United States of America (USA), were screened for thermosensitivity characteristics using different analyses. Growth curves at 0, 3, 6, 12, 24, and 30 h of incubation at 37 and 40 °C, the growth inhibition percentage at 40 °C, and the doubling time at 37 and 40 °C were determined for all yeasts studied. Most of the isolates examined exhibited thermotolerant phenotypes at 40 °C, whereas a thermosensitive phenotype at 40 °C was only detected in the Downs reference strain from the USA. Growth inhibition values lower than 33.8% supported the predominance of the thermotolerant phenotype at 40 °C. The doubling time means found for the different isolates were 5.14 h ± 1.47 h at 37 °C and 5.55 h ± 1.87 h at 40 °C. This is the first report to underscore the predominance of thermotolerant and delayed doubling time phenotypes in H. capsulatum clinical isolates from different regions of Latin America.

Postpartum histoplasmosis in an HIV-negative woman: a case report and phylogenetic characterization by internal transcribed spacer region analysis

Abstract The present report describes the first case of postpartum disseminated histoplasmosis in a 24-year-old HIV-negative woman. On the tenth day after vaginal delivery, the patient presented with dyspnea, fever, hypotension, tachycardia, and painful hepatomegaly. Yeast-like Histoplasma capsulatum features were isolated in the buffy coat. The phylogenetic analysis demonstrated that the fungal isolate was similar to other H. capsulatum isolates identified in HIV patients from Ceará and Latin America. Thus, histoplasmosis development in individuals with transitory immunosuppression or during the period of immunological recovery should be carefully examined.

Histoplasma panniculitis in a patient with systemic lupus erythematosus

Abstract: Histoplasmosis usually presents primarily as lung infection. Occasionally, mainly in immunocompromised hosts, it can spread and cause systemic manifestations. Skin lesions have been reported in 10 to 15 percent of cases of disseminated histoplasmosis, and panniculitis has been described as an unusual form of presentation in affected patients. We present the case of a patient with systemic lupus erythematosus who presented cellulitis due to disseminated histoplasmosis.

Histoplasmosis diseminada como manifestación inicial del linfoma linfocítico de células pequeñas / Disseminated histoplasmosis as a first clinical manifestation in a patient with small lymphocytic lymphoma: A case report

RESUMEN El linfoma linfocítico de células pequeñas es una neoplasia de células B maduras con un amplio espectro de presentaciones clínicas. Las infecciones por gérmenes oportunistas no asociadas con el tratamiento, incluso en estadios avanzados de la enfermedad, tienen baja incidencia. Se han reportado muy pocos casos de pacientes con linfoma linfocítico de células pequeñas asociado a histoplasmosis diseminada que no habían recibido quimioterapia en el momento del diagnóstico. Se presenta el caso de una paciente de 82 años que fue hospitalizada por presentar tos seca intermitente, astenia y adinamia de un mes de evolución. Se le practicaron múltiples estudios para detectar infecciones o compromiso inmunológico o reumático, y se diagnosticó un síndrome adenopático extenso con compromiso cervical, torácico y retroperitoneal. En la citometría de flujo y en la biopsia de ganglio linfático cervical, se reportaron los fenotipos CD19+, CD20dim, CD5+, CD45+, CD23+, CD43neg y CD10neg, con restricción de la cadena ligera kappa, lo cual confirmó un linfoma linfocítico de células pequeñas. En la histopatología del ganglio, se observaron granulomas epitelioides sin necrosis, pero las coloraciones especiales no mostraron la presencia de microorganismos, en tanto que el cultivo del ganglio fue positivo para Histoplasma capsulatum. Se inició el tratamiento antifúngico con anfotericina B e itraconazol, y la paciente tuvo una adecuada evolución. Dado que no se cumplían los criterios para el tratamiento oncológico, se continuó con su observación mediante controles periódicos. Las infecciones oportunistas pueden ser la manifestación clínica inicial en pacientes con síndromes linfoproliferativos de bajo grado. Este caso demuestra que pueden desarrollarse, incluso, en ausencia de quimioterapia.

ABSTRACT The small lymphocytic lymphoma is a mature B cell neoplasm with a broad spectrum of clinical presentations. Opportunistic infections that are not related to the treatment, even in advanced stages, have a low incidence rate. There are few case reports in the medical literature of patients who have not received immunosuppressive therapy and present with small lymphocytic lymphoma associated with disseminated histoplasmosis at diagnosis. A female 82-year-old patient was admitted due to an intermittent dry cough, asthenia, and adynamia that had persisted for one month. Multiple studies to detect infections and immuno-rheumatic conditions were performed and an extensive cervical, thoracic and peritoneal adenopathic syndrome was diagnosed. A flow cytometry and a cervical lymph node biopsy were performed reporting CD19+, CD20dim, CD5+, CD45+, CD23+, CD43neg, and CD10neg phenotypes with restriction in the light kappa chain compatible with a small lymphocytic lymphoma. Epithelioid granulomas without necrosis were observed in the lymph node histopathology and special colorations showed no microorganisms. The culture from the lymph node was positive for Histoplasma capsulatum. We initiated treatment with amphotericin B and itraconazole with an adequate response. In the absence of compliance with oncology treatment criteria, the patient was managed on a "watch and wait" basis. Opportunistic infections could be the initial clinical manifestation in patients with low-grade lymphoproliferative syndromes. This case report shows that they can develop even in the absence of chemotherapy.

Predictive factors for disseminated histoplasmosis in AIDS patients with fever admitted to a reference hospital in Brazil

Abstract INTRODUCTION: In many settings, the lack of sensitive biomarkers of disseminated histoplasmosis (DH) leads to a clinical reliance on older diagnostic methods and delayed treatment initiation. The early recognition of DH is critical for survival, especially in patients with human immunodeficiency virus (HIV). This study aimed to identify clinical and laboratory findings associated with the definitive diagnosis of DH in low-income HIV patients in endemic areas. METHODS: Febrile AIDS patients with suspected DH who were admitted to a reference hospital in northeastern Brazil from January 2006 to January 2007 were evaluated for clinical and laboratory findings associated with DH diagnosis. RESULTS: One hundred seventeen patients with fever were included, and 48 (41%) cases of DH were determined by Histoplasma capsulatum identification. A higher fever (≥38.5ºC), maculopapular/papular rash, splenomegaly, hepatomegaly, wheezing, hemoglobin ≤9.5g/dL, platelets ≤80,000/µL, CD4 count ≤75/µL, aspartate aminotransferase (AST) level ≥2.5 times the upper limit of normal (ULN), lactate dehydrogenase (LDH) ≥5times the ULN; and international normalized ratio (INR) >2 times the ULN were significantly associated with DH. A multivariable analysis identified hepatomegaly [adjusted (a) prevalence ratio (PR)= 1.96; 95% confidence interval (CI): 1.21-3.16), CD4 count ≤75/µL (aPR = 2.02; 95% CI: 1.06-3.83), LDH ≥5 times the ULN (aPR = 2.23; 95% CI: 1.44-3.48), and maculopapular/papular rash (aPR = 1.70; 95% CI: 1.02-2.83) were independent risk factors for DH. CONCLUSIONS: These easily assessed parameters can facilitate clinical decision-making for febrile AIDS patients with suspected DH in low socioeconomic and Histoplasma-endemic regions.

Histoplasma capsulatum: ¿un agente emergente para Chile? / Histoplasma capsulatum: an emerging agent in Chile?

Resumen En los últimos 11 meses, nuestro laboratorio ha diagnosticado 9 casos de histoplasmosis de presentación clínica en el territorio nacional. Todos los pacientes asociados a los cuadros clínicos son inmigrantes. Por medio del presente trabajo deseamos difundir y alertar a los profesionales de los laboratorios clínicos de nuestro país de la presencia y circulación de cepas de Histoplasma capsulatum en muestras clínicas. Asimismo, deseamos concientizar en el reforzamiento de las medidas de bioseguridad al interior de los laboratorios clínicos.

In the last eleven months, we have diagnosed 9 cases of Histoplasmosis in our country. All patients affected were from endemic areas of South-America. Here, we wish to inform and prevent to all clinical laboratories from Chile about the presence of Histoplasma capsulatum in clinical samples. In the same way we want to prepare and raising awareness of the strengthening of biosecurity measures.

Lesiones cutáneas como manifestación de una histoplasmosis diseminada en un hospital del Perú / Skin lesions of a disseminated histoplasmosis in Peru

The dermatological manifestations of disseminated histoplasmosis present in about 17% of the cases, is a challenge for its diagnosis. We report the case of a patient from the northern coast of Peru, who presented diffuse dermal lesions, erythema-violaceous nodules, and ulcers histopathologically compatible with the infection of the genus Histoplasma var. capsulatum

Histoplasmosis diagnosed after arthroscopy of the knee: case report

ABSTRACTFungal arthritis is a rare complication of arthroscopic surgeries, but its possibility should always be considered due its deleterious effects on any joint. Infection caused by the fungus Histoplasma capsulatum is the most common cause of respiratory tract infections by fungi, meanwhile histoplasmosis arthritis is more rare than all other fungal infections. However, their atypical forms of arthritis and the importance of early diagnosis and treatment cannot be over-emphasized. Herein we report a case of knee monoarthritis in an immunocompetent patient with histoplasmosis arthritis following an arthroscopic meniscetomy, diagnosed by synovial biopsy and culture performed during a second arthroscopic procedure. The joint was debrided in this second intervention and the patient received itraconazole initially and fluconazole latter on. The arthritis subsided after 10 months of treatment.

Chronic Cavitary Pulmonary Histoplasmosis in a Non-HIV and Immunocompromised Patient without Overseas Travel History

Korea is not known as an endemic area for Histoplasma. However, we experienced a case of histoplasmosis in a person who had never been abroad. A 65-year-old female was admitted to the hospital for evaluation of multiple lung nodules. A computed tomography (CT) scan of the chest showed multiple ill-defined consolidations and cavitations in all lobes of both lungs. The patient underwent a CT-guided lung biopsy, and a histopathology study showed findings compatible with histoplasmosis. Based on biopsy results and clinical findings, the patient was diagnosed with chronic cavitary pulmonary histoplasmosis. The patient recovered completely following itraconazole treatment. This is the first case report of pulmonary histoplasmosis unconnected with either HIV infection or endemicity in Korea.

Chronic Cavitary Pulmonary Histoplasmosis in a Non-HIV and Immunocompromised Patient without Overseas Travel History

Korea is not known as an endemic area for Histoplasma. However, we experienced a case of histoplasmosis in a person who had never been abroad. A 65-year-old female was admitted to the hospital for evaluation of multiple lung nodules. A computed tomography (CT) scan of the chest showed multiple ill-defined consolidations and cavitations in all lobes of both lungs. The patient underwent a CT-guided lung biopsy, and a histopathology study showed findings compatible with histoplasmosis. Based on biopsy results and clinical findings, the patient was diagnosed with chronic cavitary pulmonary histoplasmosis. The patient recovered completely following itraconazole treatment. This is the first case report of pulmonary histoplasmosis unconnected with either HIV infection or endemicity in Korea.

Histoplasmosis del sistema nervioso central en un paciente inmunocompetente / Histoplasmosis of the central nervous system in an immunocompetent patient

La histoplasmosis es una afección polifacética producida por el hongo dimorfo Histoplasma capsulatum , cuyas esporas son inhaladas y llegan al pulmón, órgano primario de infección. La forma meníngea, considerada como una de las manifestaciones más graves de esta micosis, suele presentarse en individuos con alteraciones en la inmunidad celular: pacientes con síndrome de inmunodeficiencia humana adquirida, con lupus eritematoso sistémico o con trasplante de órgano sólido, así como en lactantes, debido a su inmadurez inmunológica. La forma de presentación más usual es de resolución espontánea y se observa en individuos inmunocompetentes que se han expuesto a altas concentraciones de conidias y fragmentos miceliares del hongo. En estas personas, la afección se manifiesta por trastornos pulmonares y por la posterior diseminación a otros órganos y sistemas. Se presenta un caso de histoplasmosis del sistema nervioso central en un niño inmunocompetente.

Histoplasmosis is a multifaceted condition caused by the dimorphic fungi Histoplasma capsulatum whose infective spores are inhaled and reach the lungs, the primary organ of infection. The meningeal form, considered one of the most serious manifestations of this mycosis, is usually seen in individuals with impaired cellular immunity such as patients with acquired immunodeficiency syndrome, systemic lupus erythematous or solid organ transplantation, and infants given their immunological immaturity. The most common presentation is self-limited and occurs in immunocompetent individuals who have been exposed to high concentrations of conidia and mycelia fragments of the fungi. In those people, the condition is manifested by pulmonary disorders and late dissemination to other organs and systems. We report a case of central nervous system histoplasmosis in an immunocompetent child.

The use of nested Polymerase Chain Reaction (nested PCR) for the early diagnosis of Histoplasma capsulatum infection in serum and whole blood of HIV-positive patients* / Uso da Reação em Cadeia da Polimerase aninhada (PCR aninhada) para o diagnóstico precoce da infecção pelo Histoplasma capsulatum no soro e no sangue total de pacientes HIV positivos

The aim of the study was to detect the rDNA sequences and their regions in Histoplasma capsulatum, which could be considered species-specific and used as a molecular method for this diagnosis by the technique of nested polymerase chain reaction (nested PCR), employing specific sequences (primers) for H. capsulatum: 18S rDNA region (HC18), 100 kDa (HC100) and the sequence 5.8 S-ITS rDNA (HC5.8). The PCR sequences HC18, HC100 and HC5.8 resulted in a specificity of 100%. The molecular assays may increase the specificity, sensitivity and speed in the diagnosis of Histoplasmosis.

O objetivo do estudo consistiu em detectar seqüências no ADNr e as suas regiões no Histoplasma capsulatum, que pudessem ser consideradas espécie-específicas e usadas como método molecular para o diagnóstico pela técnica da reação em cadeia da polimerase aninhada ("nested PCR") com seqüências específicas ("primers") para H. capsulatum: regiões 18S ADNr (HC18), 100kDa (HC100) e a seqüência 5.8 S ADNr-ITS (HC5.8). A "nested PCR" com as seqüências HC18, HC100 e HC5.8 resultaram em 100% de especificidade. Os ensaios moleculares podem aumentar a especificidade, sensibilidade e rapidez na diagnose da Histoplasmose.

Evaluating fungi indoor presence in homes through viable and non-viable sampling / Evaluación de la presencia de hongos en el interior de domicilios a través de muestreo viable o no viable

Moulds are common and important allergens. They are more abundant outdoors but patients affected by mould allergy stay indoors much longer than outdoors. So, indoor sampling could help to assess the influence of the concentration of allergens in allergic symptoms. The aim of this study was to assess the relative efficiencies of two air sampling methods, viable and non viable, for the quantification of airborne indoor fungi in the homes of patients sensitized to Alternaria. Furthermore, outdoor sampling was carried out to compare results. Samples were taken over six months in Badajoz (SW Spain). Two houses were selected according to the presence of allergic patients to Alternaria. They were sampled once a month using both viable and non viable personal samplers at solar noon. A Burkard personal sampler was used to record spores and a Sampl’air AES Chemunex sampler was used for colonies. Three rooms were selected in each home: living room, kitchen and bathroom. Temperature and relative humidity were registered at each sample. Outdoor sampling was performed one day per week at the Faculty of Science, using a seven day Burkard sampler for spores and the same personal sampler for colonies. On average, 200-300 CFU/ m3 were found from more than 40 taxa identified. The highest number of colonies was recorded in the kitchen, then in the bathroom and finally in the living room. Nevertheless, there were minor differences between rooms. The houses studied showed a similar temporal pattern, with maximum values in December and minimum in January. Cladosporium colonies showed statistical differences between homes, but these differences were not found with Alternaria, Aspergillus or Penicillium colonies. Differences between rooms appeared for Alternaria colonies and Cladosporium herbarium spores. Temperature was positively correlated in most cases and relative humidity negatively with Alternaria spores.

Los hongos son alérgenos comunes e importantes. Son más abundantes en exteriores pero los pacientes afectados por alergia a los hongos permanecen en interiores mucho más tiempo que en exteriores. Por esto, el muestreo en interiores puede ayudar a evaluar la influencia de la concentración de alérgenos en los síntomas de la alergia. El objetivo de este trabajo ha sido valorar la eficiencia relativa de dos métodos de muestreo del aire, viable y no viable, para la cuantificación de hongos aerovagantes de interiores en hogares de pacientes sensibilizados a Alternaria. Adicionalmente, se ha realizado un muestreo en exteriores para comparar los resultados. Las muestras se tomaron durante seis meses en Badajoz (SO de España). Dos casas fueron seleccionadas de acuerdo a la presencia de pacientes alérgicos a Alternaria spp. Fueron muestreadas hacia el mediodía de forma mensual utilizando simultáneamente captadores personales con métodos viables y no viables. Un captador personal Burkard se utilizó para el registro de las esporas y un captador Sampl’air AES Chemunex para las colonias de hongos. Se seleccionaron tres habitaciones en cada casa, el salón, la cocina y el cuarto de baño. La temperatura y la humedad relativa fueron registradas en cada muestreo. El muestreo en el exterior se llevó cabo un día a la semana en la Facultad de Ciencias utilizando un captador Burkard 7-day para las esporas y el mismo captador personal para las colonias. En promedio se encontraron 200-300 CFU/m3 pertenecientes a más de 40 taxones identificados. El mayor número de colonias fue registrado en la cocina, luego en el cuarto de baño y finalmente en el salón. Sin embargo las diferencias entre las habitaciones fueron mínimas. Las casas estudiadas mostraron un patrón temporal similar, con valores máximos en Diciembre y mínimos en Enero.

A rare case of Histoplasma fungemia in an AIDS patient.

Disseminated cases of histoplasmosis in acquired immune deficiency syndrome (AIDS) are rarely reported from India. Most of these cases report isolation of this fungus from the bone marrow, lymph node aspirate, spleenic aspirate, and biopsies. We report isolation of Histoplasma capsulatum from the blood of an AIDS patient. A 30-year-old male from Utter Pradesh was admitted with fever, loss of appetite, and nausea since two months. Few intracellular and extracellular budding cells were observed on bone marrow examination on the fifth day of admission. Diagnosis was confirmed by blood cultures taken on the 11th day of admission. Amphotericin B was started, but the patient's condition deteriorated and he died.

Brote de histoplasmosis en la Escuela de Cadetes de la Base Aérea de Morón, Provincia de Buenos Aires, República Argentina / Histoplasmosis outbreak in Morón, Buenos Aires Province, Argentina

Se describe un brote de histoplasmosis que afectó a 6 cadetes de la Fuerza Aérea Argentina, sin antecedentes patológicos previos. Todos consultaron por problemas respiratorios después de haber limpiado un hangar. En ese recinto se encontraron abundantes deyecciones de animales, presuntamente de palomas y murciélagos. Los pacientes sufrieron fiebre, mialgias, taquipnea y tos no productiva. Las radiografías y tomografías de tórax mostraron imágenes pulmonares micronodulares, engrosamiento de los tabiques interalveolares y adenopatías hiliares. Todos tuvieron una evolución favorable y no requirieron tratamiento antifúngico. Las pruebas de inmunodifusión y contrainmunoelectroforesis con antígenos de Histoplasma capsulatum fueron positivas, al igual que las intradermorreacciones con histoplasmina. Se recogieron 5 muestras de tierra del lugar, las que fueron inoculadas por vía intraperitoneal a 20 hámsteres. De los cultivos de hígado y bazo de dichos animales se consiguió aislar la fase micelial de H. capsulatum. La cepa aislada se comparó con las obtenidas de 12 pacientes argentinos utilizando perfiles genéticos y se observó un clado único con más de 96% de similitud, lo que confirma la homogeneidad de las cepas argentinas. Si bien la histoplasmosis es endémica en la Pampa húmeda, este es el primer brote totalmente documentado al sur del paralelo 34°.

An histoplasmosis outbreak affecting 6 previously healthy Air Force cadets is herein presented. The patients suffered from fever and respiratory symptoms after having cleaned an abandoned hangar soiled with pigeons and bat droppings. They all presented fever, myalgia, tachypnea, and nonproductive cough. Chest X-ray and CT scan studies showed disseminated reticulonodular images affecting both lungs. Hiliar adenomegalies were also observed. All patients achieved a favourable outcome without antifungal treatment. Both serologic tests searching for specificic antibodies (immunodiffusion and counterimmunoelectrophoresis) and histoplasmin skin tests were positive in all cases. Five soil samples mixed with pigeons and bat droppings were collected from the hangar. Suspensions of these samples were inoculated into 20 hamsters by intraperitoneal injection; mycelial phase of H. capsulatum was isolated from liver and spleen cultures. The genetic profile of this strain was compared with 12 isolates obtained from Argentinean patients, and a great degree of homogeneity was observed (> 96% similarity). Although histoplasmosis is endemic in the wet Pampas, this is the first epidemic outbreak reported south of the 34th parallel.

Biological activity of the mite Sancassania sp. (Acari: Acaridae) from bat guano associated with the pathogenic fungus Histoplasma capsulatum

Mites and the mammal pathogenic fungus Histoplasma capsulatum are the major components of bat guano microbiota. Interactions between mites and H. capsulatum were evaluated under laboratory conditions. Acarid mites, mainly Sancassania sp., were the most abundant microarthropod in the sampled guano of the Mexican bat Tadarida brasiliensis mexicana and, based on its morphology, Sancassania sp. was similar to the cosmopolitan species Sancassania sphaerogaster. The mycophagous and vectoring activities of this mite were tested for H. capsulatum and two other fungal species, Sporothrix schenckii (pathogenic) and Aspergillus sclerotiorum (non-pathogenic). S. ca. sphaerogaster was able to reproduce in H. capsulatum and S. schenckii colonies, multiplying in great numbers under controlled fungal mycelial-phase culture conditions. H. capsulatum colonies were completely destroyed after 14 days of in vitro interaction with mites. In contrast, S. ca. sphaerogaster did not reproduce in A. sclerotiorum cultures. S. ca. sphaerogaster was found vectoring H. capsulatum, but not the two other fungal species studied.

Diagnóstico molecular de histoplasmosis humana en muestras de sangre entera / Molecular diagnosis of human histoplasmosis in whole blood samples

Se evaluó el uso de sangre entera para el diagnóstico molecular de histoplasmosis utilizando un método artesanal de extracción de ADN fúngico y una PCR anidada que amplifica una porción del gen HcP100 específica de Histoplasma capsulatum. La sangre entera se trató con liticasa, enzima lisante de Trichoderma harzianum y proteinasa K, seguido de una extracción fenólica. Este tratamiento permitió una lisis completa de las células, mostró buen rendimiento en la obtención de ADN y posibilitó la detección de la banda de 210 pb específica de H. capsulatum en la PCR anidada. El límite de detección fue de 0,25-1 levaduras/ml de sangre. El método se evaluó en 31 muestras de sangre de 19 pacientes con diagnóstico microbiológico de histoplasmosis, en 21 muestras de pacientes con otras micosis o infecciones por micobacterias y en 30 controles sanos. La PCR fue positiva en sangre para 17/19 pacientes con histoplasmosis (14/15 inmunocomprometidos y 3/4 sin inmunocompromiso aparente). Las muestras de sangre de los 30 controles sanos y de 20 pacientes con otras patologías fueron negativas, sólo hubo un falso positivo correspondiente a un paciente con infección por Mycobacterium avium-intracellulare. El método presentó 89% de sensibilidad y 96% de especificidad para el diagnóstico de histoplasmosis en sangre entera.

To assess the value of using whole blood samples for the molecular diagnosis of histoplasmosis, we applied an in-house DNA extraction method and a nested PCR targeting a 210 bp specific segment of the Histoplasma capsulatum HcP100 gene. A whole blood volume of 2.5-3 milliliters was centrifuged and the cellular pellet was treated with Trichoderma harzianum lyticase and proteinase K prior to applying a conventional phenol DNA extraction. This procedure allowed complete cell lysis, high DNA yield and specific amplification. The PCR detection limit was 0.25-1 yeast cells/ml of blood sample. The method was assessed on 31 blood samples from 19 patients with microbiological diagnosis of histoplasmosis, 30 healthy persons and 21 patients with other mycoses or mycobacterial diseases. Positive results were obtained in samples from 17/19 patients with histoplasmosis (14/15 immunocompromised and 3/4 without known immunological disorder). Blood samples from the 30 healthy controls and 20 patients with other conditions proved negative; the only false positive result was obtained from a patient with Mycobacterium avium-intracellulare infection. With 89% sensitivity and 98% specificity, this molecular method for detection of the agent in blood shows promising for the rapid diagnosis of human histoplasmosis.