Infecção por toxoplasma gondii: caracterização sorológica e molecular em pacientes atendidos pelo SUS

Abstract

T. gondii infection is high in Brazil and could lead to the development of serious sequelae such as ocular and neurological injuries, especially when it occurs during pregnancy for the risk of congenital transmission, and in immunocompromised patients. Clinical diagnosis is often difficult because the majority of affected people do not develop symptoms, therefore the use of serological and molecular methods are essential to support the diagnosis. Thus the use of sensitive and specific tests for the diagnosis of this condition is necessary. Objectives: To investigate and characterize the infection by T. gondii in their serological and molecular aspects in the northwest region of São Paulo. Methods: Peripheral blood samples were collected from patients treated in the Outpatient Clinic of High Risk Pregnancy and Fetal Medicine, and Retinopathy to analyze the serological methods (ELISA and ELFA) and molecular (cnPCR, Nested PCR and qPCR). Amniotic fluid samples were collected from pregnant women with suspect toxoplasmosis to perform the cnPCR. The results were compared using the Kappa index and calculated the sensitivity (S), specificity (SP), positive predictive value (PPV) and negative (NPV). Results: For the group of pregnant women, serological tests showed good agreement when applied to the Kappa index, G1: IgG = 0.83, IgM = 1.0; G2: IgG = 1.0, IgM = 0.78. When compared to IgM class antibodies by ELISA and ELFA had S = 75.5%, E = 100.0%, PPV = 100.0%, NPV = 87.8% and S = 79.2%, and = 100.0%, PPV = 100.0%, NPV = 89.5%, respectively. When compared to IgG showed S = 100.0%, E = 46.8%, PPV = 51.5%, NPV = 100.0% and 100.0% S = E = 38.3%, PPV = 47 7% NPV = 100.0%, respectively, and molecular methods performed by PCRs cnPCR (JW62 / 63), nested PCR, cnPCR (B22 / 23) and qPCR showed 0.0% S = E = 100, 0%, PPV = 0.0%, NPV = 63.9%, S = 5.7%, E = 100.0%, PPV = 100.0%, NPV = 65.3%, S = 7.5 % E = 98.9%, PPV = 80.0%, NPV = 65.5% and S = 1.9%, E = 100.0%, PPV = 100.0%, NPV = 64.4%, respectively. For the group of patients treated in the Retinopathy Clinic, serological tests for detection of anti-T. gondii IgG antibodies showed good agreement when applied to the Kappa index, G1: IgG = 0.97, IgM = 0.49; G2: = 0.85 IgG, IgM = 0.74. When compared to IgM class antibodies by ELISA and ELFA had S = 6.1% and = 96.8%, PPV = 62.5%, NPV = 53.7% and S = 3.7%, and = 98.9%, PPV = 75.0%, NPV = 53.7% respectively. When compared to IgG showed S = 96.3%, E = 34.6%, PPV = 56.6%, NPV = 91.4% and S = 95.1%, E = 35.7%, PPV = 56,7%, NPV = 89.2%, respectively, and the molecular methods performed by PCRs cnPCR (JW62 / 63), Nested, cnPCR (B22 / 23) and qPCR showed S = 1.8% and = 99.5 %, PPV = 75.0%, NPV = 53.3%, S = 2.4%, and 99.5%, PPV = 80.0%, NPV = 53.5%, S = 6.1% E = 98.4%, PPV = 76.7%, NPV = 54.2% and S = 8.5% and = 98.4%, PPV = 82.3%, NPV = 54.8%, respectively. For the group of neonates of 50 samples tested, 45 (90.0%) were positive for IgG 1 (2.0%) for IgM, 3 (6.0%) for IgA and 13 (26.0%) in cnPCR. Conclusion: The commercial serological tests for identifying anti- T. gondii IgG and IgM antibodies by ELISA and ELFA showed concordant results, and the molecular conventional PCR tests (cnPCR), Nested PCR and real-time PCR (qPCR) were discordant.