The Brazilian Journal of Infectious Diseases The Brazilian Journal of Infectious Diseases
Braz J Infect Dis 2017;21:638-47 - Vol. 21 Num.6 DOI: 10.1016/j.bjid.2017.07.003
Original article
Molecular diagnosis of symptomatic toxoplasmosis: a 9-year retrospective and prospective study in a referral laboratory in São Paulo, Brazil
Lilian Muniz Camiloa, Vera Lucia Pereira-Chioccolaa,, , Ricardo Gavaa, Cristina da Silva Meira-Strejevitcha, Jose Ernesto Vidalb,c,d, Cinara Cássia Brandão de Mattose, Fábio Batista Fredericof, Luiz Carlos De Mattose, Lígia Cosentino Junqueira Franco Spegiorine,g, FAMERP Toxoplasma Research Group
a Centro de Parasitologia e Micologia, Instituto Adolfo Lutz, São Paulo, SP, Brazil
b Instituto de Infectologia Emilio Ribas, São Paulo, SP, Brazil
c Faculdade de Medicina, Hospital das Clínicas, da Universidade de São Paulo, São Paulo, SP, Brazil
d Laboratório de Investigação Médica (LIM) 49, Instituto de Medicina Tropical da Universidade de São Paulo, São Paulo, SP, Brazil
e Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, SP, Brazil
f Ambulatório de Oftalmologia, Fundação Faculdade Regional de Medicina-Hospital de Base, São José do Rio Preto, SP, Brazil
g Hospital da Criança e Maternidade, São José do Rio Preto, SP, Brazil
Received 17 May 2017, Accepted 23 July 2017
Abstract

Symptomatic forms of toxoplasmosis are a serious public health problem and occur in around 10–20% of the infected people. Aiming to improve the molecular diagnosis of symptomatic toxoplasmosis in Brazilian patients, this study evaluated the performance of real time PCR testing two primer sets (B1 and REP-529) in detecting Toxoplasma gondii DNA. The methodology was assayed in 807 clinical samples with known clinical diagnosis, ELISA, and conventional PCR results in a 9-year period. All samples were from patients with clinical suspicion of several features of toxoplasmosis. According to the minimum detection limit curve (in CT), REP-529 had greater sensitivity to detect T. gondii DNA than B1. Both primer sets were retrospectively evaluated using 515 DNA from different clinical samples. The 122 patients without toxoplasmosis provided high specificity (REP-529, 99.2% and B1, 100%). From the 393 samples with positive ELISA, 146 had clinical diagnosis of toxoplasmosis and positive conventional PCR. REP-529 and B1 sensitivities were 95.9% and 83.6%, respectively. Comparison of REP-529 and B1 performances was further analyzed prospectively in 292 samples. Thus, from a total of 807 DNA analyzed, 217 (26.89%) had positive PCR with, at least one primer set and symptomatic toxoplasmosis confirmed by clinical diagnosis. REP-529 was positive in 97.23%, whereas B1 amplified only 78.80%. After comparing several samples in a Brazilian referral laboratory, this study concluded that REP-529 primer set had better performance than B1 one. These observations were based after using cases with defined clinical diagnosis, ELISA, and conventional PCR.

Keywords
Toxoplasma gondii, Symptomatic toxoplasmosis, Diagnosis, Real-time polymerase chain reaction
Braz J Infect Dis 2017;21:638-47 - Vol. 21 Num.6 DOI: 10.1016/j.bjid.2017.07.003