Diagnosis of histoplasmosis

Abstract

Endemic mycoses can be challenging to diagnose and accurate interpretation of laboratory data is important to ensure the most appropriate treatment for the patients. Although the definitive diagnosis of histoplasmosis (HP), one of the most frequent endemic mycoses in the world, is achieved by direct diagnosis performed by micro and/or macroscopic observation of Histoplasma capsulatum (H. capsulatum), serologic evidence of this fungal infection is important since the isolation of the etiologic agents is time-consuming and insensitive. A variety of immunoassays have been used to detect specific antibodies to H. capsulatum. The most applied technique for antibody detection is immunodiffusion with sensitivity between 70 to 100 % and specificity of 100%, depending on the clinical form. The complement fixation (CF) test, a methodology extensively used on the past, is less specific (60 to 90%). Detecting fungal antigens by immunoassays is valuable in immunocompromised individuals where such assays achieve positive predictive values of 96-98%. Most current tests in diagnostic laboratories still utilize unpurified antigenic complexes from either whole fungal cells or their culture filtrates. Emphasis has shifted, however, to clinical immunoassays using highly purified and well-characterized antigens including recombinant antigens. In this paper, we review the current conventional diagnostic tools, such as complement fixation and immunodiffusion, outline the development of novel diagnostic reagents and methods, and discuss their relative merits and disadvantages to the immunodiagnostic of this mycosis.

Disseminated feline histoplasmosis: a case report

“…Esta germinação e conversão podem ocorrer previamente ou após a ingestão por macrófagos pulmonares. Uma vez dentro dos macrófagos, se multiplicam e vão para os linfonodos hilar ou mediastínicos, ganhando acesso a circulação sanguínea para disseminar-se por vários órgãos (Guimarães et al, 2006), podendo envolver fígado, baço e medula óssea. Um estudo retrospectivo com imagens de ultrassom de baço de 15 gatos com histoplasmose documentou esplenomegalia em todos os animais e aparência hipoecóica em 94% dos casos (Atiee, 2014).…”

Histoplasmose pulmonar canina no estado de Pernambuco, Brasil: relato de caso

“…Apesar disso, a técnica empregada no caso relatado e a cronicidade do processo não impediram a visualização das leveduras. Guimarães et al (2006) (Kerl, 2003).…”

“…A abordagem diagnóstica é estabelecida por meio da anamnese e exame clínico do paciente, associados aos exames complementares, tais como estudo radiográfico, broncoscopia, ensaios imunoenzimáticos, testes moleculares, microbiológicos e alergocutâneos (Guimarães et al, 2006). As análises citopatológica e histopatológica das vias aéreas inferiores, além de fornecerem o diagnóstico etiológico, bem como a elucidação do mecanismo da doença, são as técnicas que apresentam maior sensibilidade.…”

Disseminated Histoplasmosis in a Patient with Aplastic Anemia

“…The gold standard for diagnosis is culture of H. capsulatum from clinical specimens. Microscopic examination of specimens stained with periodic acid-Schiff or methenamine silver may show the characteristic morphologic features of yeasts with budding and provide the rapid diagnosis [9,10]. Our diagnosis of histoplasmosis was based on the characteristic morphologic features of the fungus, and repeat biopsy for fungal culture could not be done because of refractory thrombocytopenia and poor general condition of the patient.…”