A search for the homology of our sequences with the sequences in the GenBank database was carried out by using the BLASTn program. positive by PCR. All the sequences corresponding to the 76 amplified products presented 98% NDRG1 identity withH.capsulatum. The Hc100 PCR exhibited a sensitivity of 100% and specificities of 92.4% and 95.2% when the results were compared to those for the negative controls and samples from other proven clinical entities, respectively; the positive predictive value was 83% and the negative predictive value was 100%; the positive and negative likelihood rates were 25 and 0, respectively. These results suggest that the Hc100 nested PCR assay for the detection ofH.capsulatumDNA is a useful test in areas where mycosis caused by this organism is endemic. Histoplasmosis is the most important mycosis endemic in the Americas and occurs by inhalation of the infectious propagules (microconidia) produced by the dimorphic fungusHistoplasma capsulatum(19,32). It is amply distributed in most countries, being more prevalent in specific regions of United States, such as the Mississippi and Ohio River Valleys (14,19). A high prevalence of histoplasmosis has also been Ruboxistaurin (LY333531) observed in Central America (Mexico, Panama, Honduras, Guatemala, and Nicaragua), the Caribbean (Jamaica, Puerto Rico, Cuba, and Martinique), and South America (Venezuela, French Guyana, Colombia, Peru, Brazil, and Argentina) (16,25). The severity of histoplasmosis varies greatly depending on the intensity of the exposure to the fungus and on the immune status of the infected individual (18,29). In patients with immunodeficiency disorders, and especially in those infected with HIV, histoplasmosis is considered an opportunistic infection (17,20,27); in addition, in Ruboxistaurin (LY333531) a high proportion of cases, this fungal infection is manifested as a severe disseminated process which often leads Ruboxistaurin (LY333531) to death if it is not treated promptly (17,20,27). The diagnosis of histoplasmosis is usually accomplished Ruboxistaurin (LY333531) by culture and microscopic examination of respiratory tract, biopsy, and body fluid specimens; nevertheless, these techniques yield positive results in only approximately 50% of the cases (9,16,18,32). In addition, culturing of the fungus usually takes from 2 to 6 weeks, thus delaying the times to diagnosis and the initiation of therapy. Immunological tests that detect antibodies and/or antigens are also of value and may give results faster than culture. However, they show variable values of sensitivity and specificity and may often be negative for immunodeficient patients (18). The detection of antigen in serum and urine samples appears to be a sensitive and specific diagnostic tool, especially in HIV-infected patients (81 to 95% sensitivity with urine) (8,12,13,26), although antigen detection shows cross-reactivity with the causative agents of other mycoses (12,13,16,18,30,31). In the last decade, several molecular approaches have been developed for the detection ofH. capsulatumDNA in human clinical samples. Various studies have obtained high sensitivity and specificity values for PCR-based molecular tests, including a PCR (the Hc100 PCR) that detects a gene that codes for anH. capsulatum100-kDa protein (Hc100), which is essential for the survival ofH. capsulatumin human cells (3); a PCR that detects 18S rRNA (2); a PCR that detects the internal transcribed spacer (ITS) region of the rRNA gene complex (21); and a PCR that detects the M and H antigens (4,15). Some of these PCR assays have been tested with paraffin-embedded biopsy samples (3), blood specimens (22), infected mouse tissues (2), and samples fromin vitrocultures; however, the DNA-based diagnosis of this fungal infection has not Ruboxistaurin (LY333531) yet been established as a regular diagnostic tool, nor is a PCR assay commercially available (19). In the present study, we evaluated over a 2-year period a cohort of patients with suspected or clinically diagnosed histoplasmosis,.
