XI International Meeting on Paracoccidioidomycosis

XI International Meeting on Paracoccidioidomycosis

Resume:137-2

Poster (Painel)

137-2

Serological diagnosis of paracoccidioidomycosis. Evaluation of negative serum samples on immunodiffusion test from patients with confirmed disease.

Authors:

Talísia Collachite Moreto (FMB - UNESP - Faculdade de Medicina de Botucatu - UNESP) ; Adriana Pardini Vicentini (IAL - SÃO PAULO - Instituto Adolpho Lutz) ; Angela N Passos (IAL - SÃO PAULO - Instituto Adolpho Lutz) ; V.s Kohara Kohara (IAL - SÃO PAULO - Instituto Adolpho Lutz) ; Lidia Raquel Carvalho (IBB - UNESP - Instituto de Biociencias - UNESP) ; Rinaldo Poncio Mendes (FMB - UNESP - Faculdade de Medicina de Botucatu - UNESP)

Abstract

Introduction. About 10% of paracoccidioidomycosis-patients (PCM-p) with a mycological and/or histopathological diagnosis present negative double agar gel immunodiffusion test (DID) and constituted the objective of this study. Patients and methods. Serum samples from 32 patients with confirmed PCM but negative pre-treatment DID test were evaluated. As controls, positive sera from 32 additional confirmed PCM-p were analyzed. These assays were carried out at the TDA laboratory and at the MIL. DID tests were performed using culture filtrate antigens from Pb-113 prepared at the Laboratory of Clinical Mycology – UNESP/Araraquara (DIDr); and from Pb-113 (DID1) and Pb B-339 (DID2) prepared at MIL. Immunoblotting was also carried out at MIL using strains Pb-113 (IB1) and Pb B-339 (IB2). As healthy controls serum samples from 64 Botucatu Blood Bank donors (PCM hyperendemic area) were evaluated. Sensitivity (S), specificity Sp), positive and negative predictive values (PPV and NPV), and accuracy (A) were evaluated and expressed as percentage. Statistical analysis was carried out by McNemar’s or binomial test; significance was set up at p<0.05. Results. Sensitivity of DID tests performed at TDA laboratory presented no difference as to antigens (DIDr=DID1=DID2; p>0.05), but at MIL DIDr showed lower positivity[(DID1=DID2) > DIDr; p < 0.05]. Reproducibility between laboratories was observed with DID1 and DID2, but DIDr presented higher positivity at LTDA. Immunoblotting tests presented the following accuracy findings as to antigen and glycoprotein: a) IB1gp43: S=97, Sp=50, PPV=65, NPV=94, A=73; b) IB1gp70: S=97, Sp=100, PPV=100, NPV=97, A=98; c) IB2gp43: S=92, Sp=12, PPV=52, NPV=58, A=52; d) IB2gp70: S=0, Sp=90, PPV=0, NPV=47, A=44. Conclusions. Our findings demonstrated that DID tests present high reproducibility but its sensitivity does not increase with different antigens. As to the immunoblotting tests, use of Pb 113 antigen and gp70 recognition seems to be the best choice to diagnose PCM-p.

Keyword: Serological diagnosis, negative serum, immunodiffusion test

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