Protective placental barrier against infection during pregnancy

Rare Infection Alert: What Parents Need to Know About Haemophilus influenzae and Pregnancy

Reese Marlowe in Health & Wellness June 2025 • 4 min read.

"A rare case highlights the importance of chocolate-based agar in detecting potentially dangerous infections during pregnancy and postpartum."

Pregnancy is a transformative journey, but it also brings heightened vulnerability to infections. While many infections during pregnancy are well-known, some rare cases can present unique challenges for both expectant mothers and healthcare providers. One such case involves Haemophilus influenzae (HI), a bacterium more commonly associated with childhood illnesses.

Haemophilus influenzae (HI) is a diverse group of bacteria that require specific growth factors. There are six capsular serotypes (a-f), of which type b (HIb) is the most common pathogen. However, non-typable strains (NTHI) are increasingly recognized for their role in various infections, including those affecting pregnant women and newborns.

A recent case study sheds light on a rare instance of Haemophilus influenzae placental infection associated with acute chorioamnionitis (inflammation of the fetal membranes) and acute funisitis (inflammation of the umbilical cord) in a preterm delivery. This case underscores the importance of vigilance and appropriate diagnostic techniques in prenatal care.

Understanding Haemophilus influenzae and Pregnancy Risks

Protective placental barrier against infection during pregnancy

Haemophilus influenzae (HI) is a bacterium that can cause a range of infections, from mild ear infections to severe conditions like meningitis. While HIb was once a leading cause of invasive diseases in children, widespread vaccination has significantly reduced its prevalence. However, non-typable HI (NTHI) strains remain a concern.

NTHI strains are more commonly linked to opportunistic respiratory tract infections but can also cause more severe conditions, especially in vulnerable populations such as pregnant women and newborns. HI-associated neonatal meningitis, sepsis, chorioamnionitis, and preterm delivery are rare with most cases being caused by NTHI.

Chorioamnionitis: Inflammation of the fetal membranes, which can lead to premature birth and other complications.
Funisitis: Inflammation of the umbilical cord, potentially affecting fetal oxygen and nutrient supply.
Preterm Delivery: Delivery before 37 weeks of gestation, increasing the risk of health problems for the baby.
Neonatal Sepsis: A bloodstream infection in newborns, which can be life-threatening.
Neonatal Meningitis: Inflammation of the membranes surrounding the brain and spinal cord in newborns, potentially causing long-term neurological damage.

The case study reported by Khan, Naab et al. (2014) details a 29-year-old African American woman who delivered a stillborn male fetus prematurely at 22 weeks of gestation. The placenta showed signs of acute chorioamnionitis, and the umbilical cord revealed acute funisitis. Cultures from the placenta grew non-typable beta lactamase negative HI on chocolate agar.

The Role of Chocolate Agar in Detection and Prevention

This case study highlights the importance of using chocolate-based agar for culturing specimens from pregnant women and new mothers. Chocolate agar is a specialized growth medium that allows for the isolation of fastidious organisms like Haemophilus influenzae.The study recommends that antepartum/postpartum specimens collected from maternal vagina and placenta be plated on plain chocolate agar in order to facilitate isolation of fastidious HI. By using this method, healthcare providers can more effectively detect and treat potential infections, reducing the risk of complications for both mother and child.

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Everything You Need To Know

What is Haemophilus influenzae, and why is it a concern during pregnancy?

Haemophilus influenzae (HI) is a bacterium with different strains, including type b (HIb) and non-typable strains (NTHI). While HIb infections are less common due to vaccination, NTHI can pose a risk during pregnancy. These strains are linked to conditions like chorioamnionitis, funisitis, and preterm delivery. These conditions can lead to severe complications for both the mother and the baby. HI can lead to neonatal meningitis and sepsis. The main concern during pregnancy is that infections with HI can result in severe complications for both the mother and the developing fetus, potentially leading to preterm delivery and other serious health issues.

What are the key risks associated with Haemophilus influenzae infections during pregnancy?

During pregnancy, HI infections can lead to several complications. Chorioamnionitis is the inflammation of the fetal membranes, while funisitis involves inflammation of the umbilical cord. Both can affect fetal health and may lead to preterm delivery. Preterm delivery increases the risk of health problems for the baby. Other risks include neonatal sepsis, a bloodstream infection in newborns, and neonatal meningitis, an inflammation of the membranes surrounding the brain and spinal cord in newborns, which can cause long-term neurological damage.

How does chocolate agar help in the detection of Haemophilus influenzae infections?

Chocolate agar is a specialized growth medium crucial for identifying HI infections. It allows the isolation of fastidious organisms, including Haemophilus influenzae. This is essential because HI requires specific growth factors to thrive, and chocolate agar provides these. The study recommends that samples collected from the maternal vagina and placenta be plated on chocolate agar to facilitate the detection and treatment of HI infections. This method allows healthcare providers to effectively identify potential infections and reduce complications for the mother and child.

What was the outcome of the case study involving Haemophilus influenzae?

The case study, reported by Khan, Naab et al. (2014), involved a 29-year-old African American woman who experienced a stillbirth. The delivery occurred prematurely at 22 weeks of gestation. The placenta showed signs of acute chorioamnionitis, and the umbilical cord exhibited acute funisitis. Cultures from the placenta grew non-typable beta lactamase negative HI on chocolate agar. This case underscores the critical need for vigilance and appropriate diagnostic techniques in prenatal care, particularly the use of chocolate agar to detect HI infections.

Why is it important for healthcare providers to use chocolate agar in testing for potential infections in pregnant women?

Using chocolate agar is vital because it allows healthcare providers to effectively detect and treat potential HI infections, which can cause severe complications. Chocolate agar facilitates the isolation of fastidious organisms like Haemophilus influenzae, enabling early detection. Early detection and treatment can significantly reduce the risk of complications such as chorioamnionitis, funisitis, preterm delivery, neonatal sepsis, and neonatal meningitis. This approach is essential for safeguarding both the mother and the baby's health during pregnancy and the postpartum period.