期刊论文详细信息
Revista da Sociedade Brasileira de Medicina Tropical
The performance of four molecular methods for the laboratory diagnosis of congenital toxoplasmosis in amniotic fluid samples
Leandro Emidio Teixeira1  Kelly Aparecida Kanunfre1  Paulo Tadashi Shimokawa1  Lilia Spaleta Targa1  Jonatas Cristian Rodrigues1  Wilson Domingues1  Lidia Yamamoto1  Thelma Suely Okay1 
关键词: Congenital toxoplasmosis;    Congenital infection;    Molecular diagnosis;    PCR;    Quantitative PCR;    Real-time PCR;   
DOI  :  10.1590/0037-8682-0095-2013
来源: SciELO
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【 摘 要 】

IntroductionToxoplasmosis 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.MethodsAmniotic 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).ResultsFifty-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).ConclusionsThe 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 (∞), NLR (0.017), and Ef (99%).

【 授权许可】

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