Risk factors for group B streptococcus early-onset disease: an Italian, area-based, case-control study

J Matern Fetal Neonatal Med. 2020 Jul;33(14):2480-2486. doi: 10.1080/14767058.2019.1628943. Epub 2019 Jul 17.


Purpose: Intrapartum antibiotic prophylaxis (IAP) prevents group B streptococcus (GBS) early-onset disease (EOD). No European study evaluates the relative impact of risk factors (RFs) for EOD after a screening-based strategy and widespread IAP use We aimed to evaluate the risks of EOD in an Italian region where a screening-based strategy for preventing EOD was implemented.Materials and methods: Cases of EOD born at or above 35 weeks' gestation were reviewed and matched with controls.Results: There were 109 cases of EOD among 532,154 live births. Most cases had negative GBS prenatal screening (56/91, 61.5%) and were unexposed to IAP (86/109, 78.9%). At multivariate analysis, GBS bacteriuria (OR = 6.99), positive prenatal screening (OR = 13.7) and maternal intrapartum fever (OR = 188.3) were associated with an increased risk of EOD, whereas intrapartum beta-lactam antibiotics were associated with a decreased risk of EOD (≥4 h: OR = 0.008; <4 h: OR = 0.04). Neonates born to nonfebrile, GBS positive pregnant women, receiving beta-lactam antibiotics had very low probability of EOD, particularly if IAP was adequate.Conclusions: GBS positive prenatal screening, GBS bacteriuria and intrapartum fever are associated with EOD. Intrapartum beta-lactam antibiotics reduce the probability of EOD in neonates born to nonfebrile mothers.

Keywords: Early-onset disease; GBS screening; group B streptococcus; intrapartum antibiotic prophylaxis.

MeSH terms

  • Antibiotic Prophylaxis / methods*
  • Case-Control Studies
  • Female
  • Humans
  • Incidence
  • Infant, Newborn
  • Infectious Disease Transmission, Vertical / prevention & control*
  • Italy / epidemiology
  • Pregnancy
  • Pregnancy Complications, Infectious / diagnosis
  • Prenatal Diagnosis / methods
  • Risk Factors
  • Streptococcal Infections / epidemiology
  • Streptococcal Infections / prevention & control*
  • Streptococcus agalactiae / isolation & purification
  • beta-Lactams / administration & dosage*


  • beta-Lactams