Introduction

Bacterial meningitis is a serious and life-threatening inflammation of the protective tissues surrounding the brain and spinal cord, caused by a bacterial infection. Individuals experiencing symptoms should seek immediate medical treatment, as this condition can lead to death if not treated promptly.¹ Pregnant women are at higher risk of bacterial infections, such as infections caused by Listeria, a type of bacteria that can lead to bacterial meningitis, miscarriage, stillbirth, premature birth, or infection of the newborn. There is also a risk that bacterial meningitis can be passed on to the foetus through the placenta or during delivery. This can cause a serious infection in the foetus and can be fatal.² 

This article will discuss bacterial meningitis in pregnant women and the significance of the condition. 

Understanding bacterial meningitis

Bacterial meningitis is a bacterial infection of the meninges, and the membranes surrounding the brain and spinal cord. This infection causes inflammation in the meninges, leading to swelling in brain tissue, which can lead to paralysis, stroke, or death.^1,3 Bacterial meningitis can occur in two ways:

1. Community-acquired: when the infection arises spontaneously within the community⁴
2. Nosocomial: when the infection originates in a hospital, often as a complication from medical procedures⁴ 

Meningitis is a fatal condition, requiring immediate medical attention. Meningitis can be viral or bacterial, but bacterial meningitis is the most common type. It can cause death within 24 hours.⁵ Importantly, not all patients with a bacterial infection will develop meningitis;  this depends on the individual's ability to clear the infection before it enters the bloodstream and causes inflammation at the meninges. 

Causes of bacterial meningitis

There are four main causes of bacterial meningitis:

• Neisseria meningitidis (N. meningitidis)
• Streptococcus pneumoniae (S. pneumoniae)
• Haemophilus influenzae (H. influenzae)
• Streptococcus agalactiae (S. agalactiae)⁵

These four bacteria are responsible for over half of all meningitis-related deaths globally and can cause severe complications, such as pneumonia and sepsis.⁵ Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli), Klebsiella, Enterobacter, and Pseudomonas aeruginosa are other bacteria that can cause bacterial meningitis, although they are less common. For pregnant women, S. pneumonia and L. monocytogenes are the main causative agents of bacterial meningitis.

The causes of bacterial meningitis can vary by age group:

• In newborns, S. agalactiae, S. pneumoniae, L. monocytogenes, and E. coli are more common
• In babies and younger children, S. pneumoniae, N. meningitidis, H. influenzae are the primary causes
• In teens and young adults, N. meningitidis and S. pneumoniae are most likely to cause bacterial meningitis
• In older adults, S. pneumoniae, N. meningitidis, H. influenzae, S. agalactiae and L. monocytogenes are common causative agents² 

Pathophysiology of bacterial meningitis

For bacterial meningitis to occur, bacteria must reach the meninges, which are the protective layers that surround the brain and spinal cord.³ This can be through the bloodstream, or a spread of infection from an infected site, such as the paranasal sinus of the inner ear.⁴ N. meningitidis and S. pneumoniae are capable of crossing the blood-brain barrier, which protects the central nervous system, if present in the blood.³ 

There are several steps from bacterial infection to meningitis:

1. Pathogens can enter the host by first colonising the respiratory tract (N. meningitidis and S. pneumoniae) or the gastrointestinal tract (S. agalactiae and E. coli) before entering the bloodstream⁴ 
2. Once in the bloodstream, the bacteria must survive in an environment that is not suitable for them. However, N. meningitidis, S. pneumoniae, H. influenzae, and S. agalactiae have evolved certain mechanisms to survive. The polysaccharide capsules surrounding these bacteria act as  shields, preventing the immune system from recognising and eliminating them, allowing the bacteria to remain in the bloodstream⁴ 
3. The bacteria then interact with the endothelial cells present at the blood-brain barrier, binding via surface proteins before entering the membranes surrounding the brain tissue⁴
4. This leads to an inflammatory response in the meninges, increasing pressure in the brain and causing patients to experience severe headaches and fevers³

Epidemiology of bacterial meningitis

Bacterial meningitis can affect individuals of all age groups worldwide.⁵ The prevalence of community-acquired bacterial meningitis is relatively low, with an incidence rate of 0.94 per 100,000 in 2014 in Europe, the US and Australia.⁴ The rate of bacterial meningitis has decreased over the years in developed countries, but it remains an epidemic, especially in sub-Saharan Africa.^3,4 Bacterial meningitis remains a major global public health concern, as 1 in 6 patients will die because of the disease, and 1 in 5 individuals will experience severe complications such as paralysis or stroke.⁵ 

Bacterial meningitis in pregnant people

Fortunately, bacterial meningitis is rare in pregnancy compared to the general population, but prevalence rates can vary based on geographical location, healthcare facilities, and underlying risks.⁶ L. monocytogenes and S. pneumoniae have been identified as the main causes of bacterial meningitis in pregnant people.⁷ 

Risk factors specific to pregnant people 

• L. Monocytogenes and S. pneumoniae are more likely to cause bacterial meningitis during pregnancy than other pathogens⁷
• Ear infections, such as otitis and sinusitis are important risk factors associated with a pregnant woman developing bacterial meningitis⁷ 
• Age is not considered a risk factor that increases the likelihood of developing bacterial meningitis during pregnancy

Clinical presentation and diagnosis

The symptoms of bacterial meningitis in pregnant people do not follow the usual flu-like pattern. Instead, the clinical presentations are:

• Headaches 
• Altered mental status 
• Otitis infection
• Fever⁶

Clinical evaluation begins with a medical professional taking a medical history and performing a physical examination. They will look for usual symptoms of bacterial meningitis, such as headaches, sore neck, fever and otitis infection. 

To diagnose bacterial meningitis, a lumbar puncture is performed to withdraw some cerebrospinal fluid (CSF), which is further analysed.⁷ Examples of CSF analyses include:

• Microbiological culture
• Measuring blood count and inflammatory markers
• PCR testing of the cerebrospinal fluid for the presence of bacterial DNA

Complications and prognosis of bacterial meningitis during pregnancy

Bacterial meningitis can pose serious health issues to both the pregnant person and the foetus. Spontaneous miscarriages are a common risk and are often caused by septic shock and multiorgan failure. However, symptoms are usually relatively mild and asymptomatic. However, the mortality is high for pregnant people with bacterial meningitis caused by L. monocytogenes, and mortality rates increase for newborns, with a neonatal mortality of 57%.⁷ Bacterial meningitis is rare in pregnant women but the disease does have a big impact on the health of both the gestational carrier and the foetus. 

Bacterial meningitis is a dangerous, life-threatening disease that can cause severe complications and even death if left untreated. Complications can include:

• Septic shock
• Brain herniation, the movement of brain tissue due to pressure
• Paralysis
• Stroke
• Miscarriage, stillbirth and premature birth⁷

Challenges in diagnosis during pregnancy

There are several challenges when trying to diagnose bacterial meningitis in pregnant people, including:

• The symptoms experienced by pregnant people differ from non-pregnant patients with bacterial meningitis
• Symptoms such as headaches are common during normal pregnancy, which makes diagnosis difficult
• A lumbar puncture comes with side effects that may pose risks to both the pregnant person and the foetus

Management and treatment of bacterial meningitis during pregnancy

Bacterial meningitis requires immediate intervention, typically with antibiotic therapy. For pregnant people, these can include:

• Cephalosporin
• Penicillin
• Amoxicillin
• Ceftriaxone
• Betamethasone⁷ 

However, choosing the right antibiotic is important to consider, especially for pregnant people, as some antibiotics can affect the foetus. The potential benefits and risks of each antibiotic must be carefully considered to treat bacterial meningitis effectively without causing further harm to the foetus. 

Monitoring is important for managing bacterial meningitis in pregnancy. Monitoring maternal and neonatal health is important for follow-up care and for managing any complications caused by bacterial meningitis. 

Prevention strategies

Vaccines are available that protect against the bacteria that cause bacterial meningitis:

1. Meningococcal vaccine = against N. meningitidis
2. Pneumococcal vaccine = against S. pneumoniae
3. Haemophilus influenzae type b vaccine = against H. influenzae¹

Hygiene practices are important prevention strategies to reduce transmission of the bacteria that cause bacterial meningitis.¹ These practices include washing your hands frequently, covering your mouth and nose when sneezing, and avoiding contact with infected individuals. Pregnant people are encouraged to take a Streptococcus test during the 36th or 37th week of pregnancy; if positive, antibiotics will be administered.

Conclusion

Bacterial meningitis is a serious, life-threatening disease that can cause severe complications and even death if it is not medically treated. Although the incidence of bacterial meningitis is rare in pregnant people, the prognosis is typically poor. The condition can cause serious health consequences in pregnancy, including death. Early diagnosis and antibiotic treatment increases the chance of recovery.