Rapid Classification of Serum from Patients with Paracoccidioidomycosis Using Infrared Spectroscopy, Univariate Statistics, and Linear Discriminant Analysis (LDA).

Paracoccidioidomycosis (PCM) is a systemic mycosis that is diagnosed by visualizing the fungus in clinical samples or by other methods, like serological techniques. However, all PCM diagnostic methods have limitations. The aim of this study was to develop a diagnostic tool for PCM based on Fourier transform infrared (FTIR) spectroscopy. A total of 224 serum samples were included: 132 from PCM patients and 92 constituting the control group (50 from healthy blood donors and 42 from patients with other systemic mycoses). Samples were analyzed by attenuated total reflection (ATR) and a t-test was performed to find differences in the spectra of the two groups. The wavenumbers that had p < 0.05 had their diagnostic potential evaluated using receiver operating characteristic (ROC) curves. The spectral region with the lowest p value was used for variable selection through principal component analysis (PCA). The selected variables were used in a linear discriminant analysis (LDA). In univariate analysis, the ROC curves with the best performance were obtained in the region 1551-1095 cm-1. The wavenumber that had the highest AUC value was 1264 cm-1, achieving a sensitivity of 97.73%, specificity of 76.01%, and accuracy of 94.22%. The total separation of groups was obtained in the PCA performed with a spectral range of 1551-1095 cm-1. LDA performed with the eight wavenumbers with the greatest weight from the group discrimination in the PCA obtained 100% accuracy. The methodology proposed here is simple, fast, and highly accurate, proving its potential to be applied in the diagnosis of PCM. The proposed method is more accurate than the currently known diagnostic methods, which is particularly relevant for a neglected tropical mycosis such as paracoccidioidomycosis.

Standardization of Semi-Quantitative Dot Blotting Assay-Application in the Diagnosis, Follow-Up, and Relapse of Paracoccidioidomycosis.

INTRODUCTION: This study standardized a semi-quantitative dot blotting assay (DB) and a quantitative real-time polymerase chain reaction (qPCR) to detect specific antibodies for Paracoccidioides brasiliensis and its DNA in PCM patients. METHODOLOGY: We evaluated 42 confirmed PCM patients upon admission using a serological double agar gel immunodiffusion test (DID), DB, and molecular tests (qPCR in total blood). The control groups included 42 healthy individuals and 37 patients with other infectious diseases. The serological progress during treatment was evaluated in eight patients, and there was a relapse diagnosis in ten patients using the Pb B.339 strain antigen. The cut-off points for the serological tests were determined by a receiver operator characteristic curve. RESULTS: The DB and DID tests showed similar accuracy, but the DB identified lower antibody concentrations. Cross-reactions were absent in the DB assay. In the relapse diagnoses, DB exhibited much higher sensitivity (90%) than DID (30%). CONCLUSIONS: A DB assay is easier and faster than a DID test to be performed; DB and DID tests show the same accuracy, while blood qPCR is not recommended in the diagnosis at the time of admission; cross-reactions were not observed with other systemic diseases; DB and DID tests are useful for treatment monitoring PCM patients; and a DB assay is the choice for diagnosing relapse. These findings support the introduction of semi-quantitative DB assays in clinical laboratories.

Reproducibility of double agar gel immunodiffusion test using stored serum and plasma from paracoccidioidomycosis patients.

Background: Serological evaluation performed by double agar gel immunodiffusion test (DID) is used for diagnosis, evaluation of severity, management of paracoccidioidomycosis patients, and development of new clinical studies. For these reasons, the Botucatu Medical School of UNESP maintains a serum bank at the Experimental Research Unit with patient clinical data. This study aimed to evaluate the influence of the freeze-thaw cycle and different blood matrices on the titration of circulating antibodies. Methods: The study included 207 patients with confirmed (etiology-demonstrated) or probable (serology-demonstrated) paracoccidioidomycosis, and DID was performed with culture filtrate from Paracoccidioides brasiliensis B339 as antigen. First experiment: the antibody levels were determined in serum samples from 160 patients with the chronic form and 20 with the acute/subacute form, stored at -80oC for more than six months. Second experiment: titers of 81 samples of serum and plasma with ethylenediaminetetraacetic acid (EDTA) or heparin, from 27 patients, were compared according to matrix and effect of storage at -20oC for up to six months. Differences of titers higher than one dilution were considered discordant. Results: First experiment: test and retest presented concordant results in serum stored for up to three years, and discordant titers in low incidence in storage for four to six years but high incidence when stored for more than six years, including conversion from reagent test to non-reagent retest. Second experiment: serum, plasma-EDTA and plasma-heparin samples showed concordant titers, presenting direct correlation, with no interference of storage for up to six months. Conclusions: Storage at -80oC for up to six years has no or little influence on the serum titers determined by DID, permitting its safe use in studies depending on this parameter. The concordant titrations in different blood matrices demonstrated that the plasma can be used for immunodiffusion test in paracoccidioidomycosis, with stability for at least six months after storage at -20oC.

A scoping study of pulmonary paracoccidioidomycosis: severity classification based on radiographic and tomographic evaluation.

The lungs have great importance in patients with paracoccidioidomycosis since they are the portal of entry for the infecting fungi, the site of quiescent foci, and one of the most frequently affected organs. Although they have been the subject of many studies with different approaches, the severity classification of the pulmonary involvement, using imaging procedures, has not been carried out yet. This study aimed to classify the active and the residual pulmonary damage using radiographic and tomographic evaluations, according to the area involved and types of lesions.

Using infrared spectroscopy of serum and chemometrics for diagnosis of paracoccidioidomycosis.

Paracoccidioidomycosis (PCM) is a systemic granulomatous mycosis endemic to Latin America, whose etiologic agents are fungi of the genus Paracoccidioides. PCM is usually diagnosed by microscopic observation of the fungus in biological samples, combined or not with other techniques such as serological methods. However, all currently used diagnostic methods have limitations. The objective of this study was to develop a method based on Fourier transform infrared spectroscopy (FTIR) and chemometric analysis for PCM diagnosis. We included 224 serum samples: 132 PCM sera, 24 aspergillosis sera, 10 cryptococcosis sera, 8 histoplasmosis sera, and 50 sera from healthy blood donors. Samples were analyzed by attenuated total reflection (ATR), and chemometric analyses including exploratory analysis through principal component analysis (PCA) and a classification method (PCM and non-PCM) through orthogonal partial least squares discriminant analysis (OPLS-DA). The spectra were similar, with the main bands up to approximately 1652 cm-1 and 1543 cm-1 (amide I and amide II bands). This same region was mainly responsible for the partial separation of the samples in PCA. The OPLS-DA model correctly classified all serum samples with only one latent variable, with a determination coefficient (R²) higher than 0.999 for both the calibration set and prediction set. Sensitivity and specificity were 100% for both sets, showing better performance than the reference diagnostic methods. Therefore, the use of FTIR/ATR together with OPLS-DA modeling proved to be a promising method for PCM diagnosis.

Antifungal activity of liriodenine on clinical strains of Cryptococcus neoformans and Cryptococcus gattii species complexes.

Background: Cryptoccocal meningitis continues to present high incidence among AIDS patients. The treatment of choice is the synergistic combination of flucytosine (5-FC) with amphotericin B deoxycholate (AmBd) or its lipid formulations. However, 5-FC is unavailable in many countries and AmB demands hospitalization. The combination of AmB with the fungistatic fluconazole (FLC) or the use of high FLC daily doses alone became the choice. Nonetheless, sterilization of cerebrospinal fluid is delayed with FLC monotherapy, mainly with high fungal burden. These findings suggest the search for new antifungal compounds, such as liriodenine. Methods: Liriodenine antifungal activity was evaluated by three procedures: determining the minimum inhibitory concentration (MIC) on 30 strains of the Cryptococcus neoformans (C. neoformans) complex and 30 of the Cryptococcus gattii (C. gattii) complex, using EUCAST methodology and amphotericin B deoxycholate as control; performing the time-kill methodology in two strains of the C. neoformans complex and one of the C. gattii complex; and injury to cryptococcal cells, evaluated by transmission electron microscopy (TEM). Liriodenine absorption and safety at 0.75 and 1.50 mg.kg-1 doses were evaluated in BALB/c mice. Results: Liriodenine MICs ranged from 3.9 to 62.5 µg.mL-1 for both species complexes, with no differences between them. Time-kill methodology confirmed its concentration-dependent fungicidal effect, killing all the strains below the limit of detection (33 CFU.mL-1) at the highest liriodenine concentration (32-fold MIC), with predominant activity during the first 48 hours. Liriodenine induced severe Cryptococcus alterations - cytoplasm with intense rarefaction and/or degradation, injury of organelles, and presence of vacuoles. Liriodenine was better absorbed at lower doses, with no histopathological alterations on the digestive tract. Conclusion: The fungicidal activity confirmed by time-kill methodology, the intense Cryptococcus injury observed by TEM, the absorption after gavage administration, and the safety at the tested doses indicate that the liriodenine molecule is a promising drug lead for development of anticryptococcal agents.

A scoping study of pulmonary paracoccidioidomycosis: severity classification based on radiographic and tomographic evaluation

The lungs have great importance in patients with paracoccidioidomycosis since they are the portal of entry for the infecting fungi, the site of quiescent foci, and one of the most frequently affected organs. Although they have been the subject of many studies with different approaches, the severity classification of the pulmonary involvement, using imaging procedures, has not been carried out yet. This study aimed to classify the active and the residual pulmonary damage using radiographic and tomographic evaluations, according to the area involved and types of lesions.