Group B Streptococcus early-onset disease and observation of well-appearing newborns

Abstract

Background: International guidelines lack a substantial consensus regarding management of asymptomatic full-term and late preterm neonates at risk for early-onset disease (EOS). Large cohorts of newborns are suitable to increase the understanding of the safety and efficacy of a given strategy.

Methods: This is a prospective, area-based, cohort study involving regional birth facilities of Emilia-Romagna (Italy). We compared cases of EOS (at or above 35 weeks' gestation) registered in 2003-2009 (baseline period: 266,646 LBs) and in 2010-2016, after introduction of a new strategy (serial physical examinations, SPEs) for managing asymptomatic neonates at risk for EOS (intervention period: 265,508 LBs).

Results: There were 108 cases of EOS (baseline period, n = 60; intervention period, n = 48). Twenty-two (20.4%) remained asymptomatic through the first 72 hours of life, whereas 86 (79.6%) developed symptoms, in most cases (52/86, 60.5%) at birth or within 6 hours. The median age at presentation was significantly earlier in the intrapartum antibiotic prophylaxis (IAP)-exposed than in the IAP-unexposed neonates (0 hours, IQR 0.0000-0.0000 vs 6 hours, IQR 0.0000-15.0000, p<0.001). High number of neonates (n = 531) asymptomatic at birth, exposed to intrapartum fever, should be treated empirically for each newborn who subsequently develops sepsis. IAP exposed neonates increased (12% vs 33%, p = 0.01), age at presentation decreased (median 6 vs 1 hours, p = 0.01), whereas meningitis, mechanical ventilation and mortality did not change in baseline vs intervention period. After implementing the SPEs, no cases had adverse outcomes due to the strategy, and no cases developed severe disease after 6 hours of life.

Conclusions: Infants with EOS exposed to IAP developed symptoms at birth in almost all cases, and those who appeared well at birth had a very low chance of having EOS. The risk of EOS in neonates (asymptomatic at birth) exposed to intrapartum fever was low. Although definite conclusions on causation are lacking, our data support SPEs of asymptomatic newborns at risk for EOS. SPEs seems a safe and effective alternative to laboratory screening and empirical antibiotic therapy.

Fig 1. EOS cases (at or above 35 weeks of gestation) in the 2 study periods (2003–2009 vs 2010–2016).

Cases are divided according to the presence (or absence) of risk factors, the presence (or absence) of symptoms during the first 72 hours of life and the time of onset of symptoms. Cases of severe disease are shown in the grey boxes. Neonates managed through SPEs are shown in the dashed box.ARN, at-risk neonates; EOS, early-onset disease; h, hours; NARN, not at-risk neonates; wks, weeks. ¶ One neonate with severe disease was unexposed to IAP; he was born preterm (36 weeks of gestation) to an unscreened mother, and symptoms developed at 2 hours of age. Another neonate was treated in labour with 8 doses of clindamycin; he was born after a prolonged membrane rupture (60 hours) and symptoms developed at 4 hours of age.

Fig 2. Age of onset of symptoms among IAP-exposed and unexposed neonates (asymptomatic neonates are excluded).

IAP, intrapartum antibiotic prophylaxis. Empty bars: cases unexposed to IAP. Black bars: cases exposed to any IAP. Symptoms developed at 0 hours (beta-lactam antibiotics ≥4 hours, n = 4; beta-lactam antibiotics <4 hours, n = 4; non-beta-lactam antibiotics, n = 5). Symptoms developed at 1 to 6 hours (non-beta-lactam antibiotics, n = 1). Symptoms developed at >6 hours (beta-lactam antibiotics ≥4 hours, n = 1).