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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The performance of four molecular methods for the laboratory diagnosis of congenital toxoplasmosis in amniotic fluid samples

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Author(s):
Teixeira, Leandro Emidio [1] ; Kanunfre, Kelly Aparecida [1, 2] ; Shimokawa, Paulo Tadashi [1] ; Targa, Lilia Spaleta [1] ; Rodrigues, Jonatas Cristian [1, 2] ; Domingues, Wilson [1] ; Yamamoto, Lidia [1] ; Okay, Thelma Suely [1]
Total Authors: 8
Affiliation:
[1] Univ Sao Paulo, Inst Med Trop Sao Paulo, Lab Soroepidemiol & Imunobiol, Sao Paulo - Brazil
[2] Univ Sao Paulo, Fac Med, Dept Doencas Infecciosas & Parasitarias, Lab Imunol, Sao Paulo - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Revista da Sociedade Brasileira de Medicina Tropical; v. 46, n. 5, p. 584-588, SEP-OCT 2013.
Web of Science Citations: 14
Abstract

Introduction: Toxoplasmosis may be life-threatening in fetuses and in immune-deficient patients. Conventional laboratory diagnosis of toxoplasmosis is based on the presence of IgM and IgG anti-Toxoplasma gondii antibodies; however, molecular techniques have emerged as alternative tools due to their increased sensitivity. The aim of this study was to compare the performance of 4 PCR-based methods for the laboratory diagnosis of toxoplasmosis. One hundred pregnant women who seroconverted during pregnancy were included in the study. The definition of cases was based on a 12-month follow-up of the infants. Methods: Amniotic fluid samples were submitted to DNA extraction and amplification by the following 4 Toxoplasma techniques performed with parasite B1 gene primers: conventional PCR, nested-PCR, multiplex-nested-PCR, and real-time PCR. Seven parameters were analyzed, sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and efficiency (Ef). Results: Fifty-nine of the 100 infants had toxoplasmosis; 42 (71.2%) had IgM antibodies at birth but were asymptomatic, and the remaining 17 cases had non-detectable IgM antibodies but high IgG antibody titers that were associated with retinochoroiditis in 8 (13.5%) cases, abnormal cranial ultrasound in 5 (8.5%) cases, and signs/symptoms suggestive of infection in 4 (6.8%) cases. The conventional PCR assay detected 50 cases (9 false-negatives), nested-PCR detected 58 cases (1 false-negative and 4 false-positives), multiplex-nested-PCR detected 57 cases (2 false-negatives), and real-time-PCR detected 58 cases (1 false-negative). Conclusions: The real-time PCR assay was the best-performing technique based on the parameters of Se (98.3%), Sp (100%), PPV (100%), NPV (97.6%), PLR (co), NLR (0.017), and Ef (99%). (AU)

FAPESP's process: 10/15022-1 - Frequency of HLA-DQA1 and DQB1 alleles in fetuses with toxoplasmosis: association with the parasite genotype and the parasite load
Grantee:Thelma Suely Okay
Support type: Regular Research Grants