Avaliação das técnicas de PCR convencional e qPCR em relação ao padrão-ouro para a detecção de streptococcus agalactiae em gestantes.

Abstract

Streptococcus agalactiae or Group B Streptococcus (GBS) is one of the main causative agents of invasive neonatal infections. Maternal colonization by SGB is the main risk factor for vertical transmission and the development of neonatal infections. Screening of pregnant women between the 35th and 37th weeks of pregnancy and antimicrobial administration during labor to colonized patients is an effective strategy for the prevention of neonatal infections. Currently the method considered the gold standard for detection of GBS is the microbiological culture. In this study, we aimed to evaluate the performance of conventional PCR and PCR in real-time (qPCR) assays, as screening methods for GBS in pregnant women compared to the gold standard. We conducted a cross-sectional study, which analyzed 130 samples of anal / vaginal combined material, pregnant women at 35 weeks or more of gestation, treated at Hospital de Clínicas de Porto Alegre (HCPA). The results were evaluated for the sensitivity, specificity, positive and negative predictive values of both PCR assays. Statistical analysis was performed using SPSS version 20.0 program. The verified colonization rate was 3.8% through the gold standard, 17.7% by the conventional PCR assay and 29.2% in the test qPCR. The trials of conventional PCR and qPCR showed a sensitivity of 100%, specificity of 85.6% and 73.6% respectively. The negative predictive value was 100% in both tests and the positive predictive value was 21.7% in the conventional PCR assay and 13.1% in the qPCR test. The qPCR assay evaluated, showed high performance when compared to the gold standard and greater detection of colonization by SGB compared to conventional PCR assay. It offers results in a shorter period, demonstrating the potential to be used in routine screening, contributing to the optimization of preventive approaches to neonatal GBS infection.