Group B serotypes prevalence at time of delivery in high-risk pregnant women in a private maternity in São Paulo

Abstract

IntroductionThe group B Streptococcus (GBS) or Streptococcus agalactiae is the main etiologic agent of neonatal sepsis worldwide. Maternal colonization of the genitourinary and gastrointestinal tract is the primary risk factor for the disease. Clinically, neonatal infection may present as early sepsis (ES) until the seventh day route, or as late onset sepsis (LOS) between seven and 89 days of life.It is estimated that 10-30% of pregnant women are colonized with GBS in their genital or intestinal tract and that half of their newborns will be colonized by bacteria.According to the Centers for Disease Control and Prevention (CDC), in United States of America (USA), there were about 7,500 cases of early sepsis annually in the country (2-3 cases per 1000 live births) before the introduction of routine intrapartum prophylaxis .Some vaccines for GBS are at different stages of clinical development, and may allow the reduction of early and late forms of the disease, but until now the main strategy for preventing neonatal infection is the identification of pregnant women colonized by bacteria (Tracking) associated with the use of intrapartum antibiotics.The GBS is an aerobic gram positive encapsulated diplococcic and - in accordance with the polysaccharide composition of its external capsule - can be classified into 10 different serotypes: Ia, Ib, II, III, IV, V, VI, VII, VIII and IX. The prevalence of these serotypes varies in different populations and there are few Brazilian studies evaluating such distribution.The knowledge of the most prevalent serotypes in different populations - with the expectation that we can count on multivalent vaccines against GBS - brings the possibility of planning the antigenic composition of candidate vaccine and estimating their potential efficacy and effectiveness in a given population.ObjectiveThe objective of this study is to determine the prevalence of serotypes of Streptococcus group B (GBS) in risk pregnant women at delivery in a private hospital in São Paulo. As a secondary objective, this study will seek to correlate these findings with gestational and demographic variables. This study was approved by the Committee on Ethics in Research (CER) of UNIFESP, see number 933,138.MethodologyThe study will be conducted at the complex of private hospitals in the city of São Paulo, namely Hospital e Maternidade Santa Joana and ProMatre Paulista, which perform about 1,200 and 800 deliveries per month, respectively.As part of the routine investigation and the institutions of the intrapartum prophylaxis, defined by the infection control committee related to health hospitals, vaginal and anal swabs of pregnant women considered at risk at the time of hospital admission are collected for GBS research. Pregnant women are considered at risk when there is: rupture of membranes for more than 18 hours, prematurity, maternal fever or chorioamnionitis signals.Positive samples for GBS will be sent to the Special Laboratory of Microbiology (LEMC) UNIFESP and analyzed to identify the different serotypes.The sample size was estimated based on the prevalence reported in the literature of the less common serotypes (IV and V). 95% IC (alpha error type 5%) and margin of error of 5%, it came to the sample size of 400 isolates.After DNA molecular extraction, GBS micro- organism identification will be done through a polymerase chain reaction (PCR) using a pair of specific primers (CFB) to each serotype (Ia - VIII).Result analysis: data analysis will reveal the proportional distribution among the different serotypes of GBS colonizing risk pregnant women and any demographic and gestational variables that may relate to this distribution. (AU)