Abstract
Paracoccidioidomycosis (PCM) cannot always be diagnosed by conventional means such as direct examination of histopathology or clinical samples, and serological methods, used as an alternative, still have many cases of cross-reactivity. In this scenario, molecular techniques seem to arise as a rapid approach, specific and direct that could be used in the diagnosis of this mycosis. In this study we analyzed 76 serum samples from patients in southern Bahia suspected of having paracoccidioidomycosis using a conventional PCR with primers for the ITS1 ribosomal DNA of P. brasiliensis. Of these 76 patients, 5 were positive for PCM by double immunodiffusion and/or direct examination and histopathology. To test specificity of PCR, we used human DNA and three isolates of P. lutzii (1578, 01 and ED01). Additionally, we analyzed by serial dilutions of DNA the limit of detection of the assay. The test of PCR proved specific, as only a 144 bp fragment of the three isolates of P. lutzii and no human DNA was amplified. Detection limit was 1.1 pg/µL of DNA. Despite the high detection limit and specificity of PCR none of the 76 serum samples were found positive by PCR, but a biopsy specimen obtained from one of the patients with PCM was positive. These results, albeit limited, show that PCR is not effective in detecting DNA of P. brasiliensis or P. lutzii in serum, but could perhaps be used with other types of clinical samples, especially in those instances in which conventional methods fail.
Highlights
Paracoccidioidomycosis (PCM) is a deep mycosis caused by the thermo-dimorphic fungus Paracoccidioides brasiliensis, endemic in some countries of Latin America, mainly in Brazil [1]
We aim to develop a conventional PCR using a pair of primers specific for the known ITS1 region of ribosomal DNA of P. brasiliensis [13], and know what is the viability of this PCR in serum samples
Paracoccidioidomycosis (PCM) has been included in such diseases neglected since this impact on public health have not been measured
Summary
Paracoccidioidomycosis (PCM) is a deep mycosis caused by the thermo-dimorphic fungus Paracoccidioides brasiliensis, endemic in some countries of Latin America, mainly in Brazil [1]. In this disease, the fungus can remain confined in the lungs, the primary focus of infection, or spread to other organs and tissues, resulting in different clinical manifestations. The conventional diagnosis of PCM is based on viewing and/or isolation of the fungus in clinical specimens. The specimen may not always be viewed and microbiological culture is time-consuming and mostly negative [3]. The scene of the PCM have been changed since the discovery of a new species, P. lutzii, which has very distinct behaviors of P. brasiliensis [6]
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