Neonatal Sepsis: Definition, Causes & Types

Instructor: Jennifer Reyes

Jennifer has taught Nursing in ADN, BSN, and MSN programs and has a Master's degree in Nursing Education.

Neonatal sepsis is a potential fatal issue affecting newborns. This lesson explores the various types, definitions, and causes of neonatal sepsis. In addition, a brief overview of risk-factors associated with sepsis will be explored.

Neonatal Sepsis

Sepsis is not exclusive to one type of person or problem. Sepsis usually refers to a harmful bacteria or toxin being present in the body. Neonatal sepsis refers to harmful bacteria or toxin being present in the neonate. The neonatal time period is defined as any infant less than four weeks old. This includes infants born prematurely.


The are many physical and chemical barriers throughout the human body to protect us from infection. These barriers are in place when the newborn is born. However, the barriers are functioning at a severe deficit and are therefore not adequately protecting the newborn from illness and harm. Skin is the largest barrier and is also the first line of defense when fighting infection. Skin and mucous membranes are broken down more easily in the premature infant. Neonates who are ill, premature or both are at additional risk because of the invasive procedures that breach their physical barriers to infection.

Several organisms and risks factors exist that can cause sepsis in the neonate. The most common organisms that lead to sepsis include:

  • Group B Streptococcus (GBS)
  • Escherichia coli
  • Coagulase-negative Staphylococcus
  • Haemophilus influenzae
  • Listeria monocytogenes

In addition to specific organisms, there are several risk factors that may predispose a neonate to sepsis. Risk factors are based on the type of sepsis. These risk factors can give neonatologists important clues to the level of stress and illness the fetus had to ensure during the delivery process, as well as the hazardous uterine environment surrounding the fetus before delivery. Early-onset, late-onset, and antibiotic-resistant are the most common types of sepsis.

Types of Neonatal Sepsis

Early-onset neonatal sepsis refers to the presence of a sepsis infection within the first 72 hours of birth for the premature, hospitalized neonate. Early-onset neonatal sepsis is most commonly associated with GBS. However, early-onset sepsis caused by E. coli is the most fatal. Early-onset sepsis is associated with the following risk factors as well:

  • Maternal GBS colonization (especially if untreated during labor)
  • Premature rupture of membranes (PROM)
  • Preterm rupture of membranes
  • Prolonged rupture of membranes (greater than 18 hours)
  • Prematurity
  • Maternal urinary tract infection
  • Chorioamnionitis
  • Low Apgar score (< 6 at 1 or 5 minutes)
  • Maternal fever greater than 38°C
  • Maternal urinary tract infection (UTI)
  • Poor or no prenatal care
  • Poor maternal nutrition
  • Low socioeconomic status
  • African American mother
  • History of recurrent abortion
  • Maternal substance abuse
  • Low birth weight
  • Meconium staining
  • Congenital anomalies

Late-onset sepsis is sepsis occurring within 4-90 days of life and is often associated with the environment in which the neonate exists in. It is often associated with the following risk factors:

  • Prematurity
  • Central venous catheterization (duration >10 days)
  • Nasal cannula or continuous positive airway pressure (CPAP) use
  • H 2 -receptor blocker or proton pump inhibitor (PPI) use
  • GI tract pathology such as necrotizing enterocolitis (NEC)

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