Aplicación de ensayos de PCR en tiempo real para el diagnóstico de histoplasmosis utilizando tres dianas moleculares en tejidos FFPE humanos y sangre completa

Objective: Histoplasmosis is a fungal infection that causes significant morbidity and mortality in persons living with HIV/AIDS, especially in countries with limited resources. Currently used diagnostic tests rely on culture and serology, lack sensitivity and often require weeks to obtain results causing significant diagnosis delays; molecular assays are not commercially available. Methods: we aimed to apply quantitative real-time PCR (qPCR) targeting three protein-coding genes of Histoplasma capsulatum (100-kDa, H and M antigens) for detection of H. capsulatum infection in formalin-fixed paraffin-embedded (FFPE) and whole blood (WB) samples from patients with proven histoplasmosis. Results: For FFPE samples, the sensitivity of 100-kDa, H and M qPCR assays were 93.9%, 91% and 57%, respectively; however, the same qPCR assays showed only 23%, 19% and 11.5% of sensitivity for 100-kDa, H y M qPCR assays when used with the WB samples. The specificity of qPCR was determined by testing samples from patients with other clinical infections and healthy controls and was 93%-100% depending upon the assay and the specimen type. Conclusion: we applied three qPCR assays for detecting H. capsulatum DNA in human samples, and demonstrated that the molecular protocols based on amplification of 100-kDa and H antigen can be successfully used for diagnosing this mycosis when using FFPE samples; however, we do not recommend WB for routine diagnosis of histoplasmosis by qPCR in patients with progressive disseminated histoplasmosis

Understanding the exposure risk of aerosolized Coccidioides in a Valley fever endemic metropolis

Coccidioides is the fungal causative agent of Valley fever, a primarily pulmonary disease caused by inhalation of fungal arthroconidia, or spores. Although Coccidioides has been an established pathogen for 120 years and is responsible for hundreds of thousands of infections per year, little is known about when and where infectious Coccidioides arthroconidia are present within the ambient air in endemic regions. Long-term air sampling programs provide a means to investigate these characteristics across space and time. Here we present data from > 18 months of collections from 11 air sampling sites across the Phoenix, Arizona, metropolitan area. Overall, prevalence was highly variable across space and time with no obvious spatial or temporal correlations. Several high prevalence periods were identified at select sites, with no obvious spatial or temporal associations. Comparing these data with weather and environmental factor data, wind gusts and temperature were positively associated with Coccidioides detection, while soil moisture was negatively associated with Coccidioides detection. These results provide critical insights into the frequency and distribution of airborne arthroconidia and the associated risk of inhalation and potential disease that is present across space and time in a highly endemic locale. © 2024, The Author(s).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Molecular characterization of environmental Cryptococcus neoformans isolated in Vitoria, ES, Brazil Caracterização molecular de cepas ambientais de Cryptococcus neoformans isoladas em Vitória, ES, Brasil

Cryptococcus neoformans is the major cause of fungal meningitis, a potentially lethal mycosis. Bird excreta can be considered a significant environmental reservoir of this species in urban areas, thirty-three samples of pigeon excreta were collected within the city of Vitoria, Brazil. Cryptococcus neoformans was isolated and identified using standard biochemical assays in ten samples. PCR amplification with primer M13 and orotidine monophosphate pyrophosphorylase (URA5) gene-restriction fragment length polymorphism (RFLP) analysis discerned serotypes and genotypes within this species. All isolates were serotype A (C. neoformans var. grubii) and genotype VNI. The two alternative alleles a and &#945; at the mating type locus were determined by PCR amplification and mating assays performed on V8 medium. All isolates were MAT &#945; mating type but only 50% were able to mate in vitro with the opposite mating type MAT a tester strains (JEC20, KN99a and Bt63). This study adds information on the ecology and molecular characterization of C. neoformans in the Southeast region of Brazil.<br>O "complexo Cryptococcus neoformans" é constituído por C. neoformans var. neoformans, C. neoformans var. grubii, e C. gattii. Trinta por cento de amostras de excrementos de pombos coletados dentro da cidade de Vitória, Brasil, foram positivas para Cryptococcus neoformans, espécie identificada por testes bioquímicos convencionais. Amplificação por PCR com primer M13 e análise por orotidine monophosphate pyrophosphorylase (URA5) gene-"restriction fragment length polymorphism" (RFLP) distinguiram sorotipos e genotipos dentro desta espécie. Todos os isolados ambientais foram sorotipo A (C. neoformans var. grubii) e genotipo VNI. Os dois alelos alternativos a e &#945; do locus "mating type" foram determinados por PCR e por testes de "mating" em meio V8. Todos os isolados foram "mating type" tipo MAT &#945; mas somente 50% foram capazes de conjugar in vitro com cepas MAT a, de "mating type" oposto (JEC20, KN99a e Bt63). Este estudo adiciona informações sobre a ecologia e caracterização molecular de cepas ambientais de C. neoformans, isoladas na região sudeste do Brasil