Transmissão vertical do Streptococcus agalactiae: revisão sistemática da literatura científica

Abstract

This study aimed to conduct a systematic review on maternal colonization by Streptococcus agalactiae (GBS), vertical transmission rates, and associated risk factors across different geographic and socioeconomic contexts. A literature search was performed in PubMed/MEDLINE, Embase, and SciELO. Original studies published in peer-reviewed journals, available in full text, without temporal restriction, addressing maternal colonization prevalence, vertical transmission rates, and/or associated risk factors were included. Only studies involving pregnant women and newborns up to 90 days of age, published in English, Portuguese, or Spanish, were considered, while reviews, case reports, letters to the editor, editorials, conference proceedings, and studies with exclusively animal or in vitro samples were excluded. Data were organized into comparative tables, enabling descriptive synthesis and qualitative analysis. The review identified wide variability in maternal colonization prevalence (4.8% to 32%) and vertical transmission rates (0.0% to 72.3%). The average vertical transmission rate across the included studies was approximately 21% (21.8% by simple mean; 21.2% weighted by sample size), reflecting the variable impact of prophylaxis practices and population differences. Studies with systematic intrapartum prophylaxis reported minimal transmission, whereas contexts without universal screening exhibited high rates. Recurring risk factors included premature rupture of membranes, prolonged labor, prematurity, and low maternal IgG levels. Methodological and geographic heterogeneity underscores the need for universal screening, effective prophylaxis, and continuous surveillance. Furthermore, only a small proportion of identified studies provided data on vertical transmission, highlighting a gap in the literature. In conclusion, these findings emphasize the importance of maternal screening policies, consistent implementation of intrapartum prophylaxis, and maternal immunization strategies to reduce Streptococcus agalactiae vertical transmission and prevent early neonatal infections.