Which pathogens are associated with meningitis in neonates (0-2 months) among the most common etiologies?

• A. Group B Streptococcus, Escherichia coli, and Listeria monocytogenes
• B. Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae
• C. Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae
• D. Listeria monocytogenes, Haemophilus influenzae, Streptococcus pyogenes

Answer: (A)

In neonates, meningitis is most often caused by organisms that can be transmitted from the mother during birth or present very early after birth. The three pathogens most consistently seen in this age group are Group B Streptococcus (Streptococcus agalactiae), Escherichia coli, and Listeria monocytogenes.

Group B Streptococcus is carried by many pregnant women in the birth canal. If not prevented by intrapartum antibiotics, it can be transmitted to the newborn during delivery, leading to early-onset sepsis and meningitis. Escherichia coli, especially certain virulent strains, is another major cause of neonatal meningitis, often presenting with sepsis and CNS involvement due to its ability to invade the immature blood-brain barrier. Listeria monocytogenes, though less common than GBS or E. coli, is an important neonatal pathogen that can be transmitted transplacentally or during birth and can cause serious CNS infection in this age group.

Other organisms such as Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, or Streptococcus pyogenes are more typical causes of meningitis in older children or adults or in specific contexts, and they are much less common as neonatal pathogens. Therefore, the combination of Group B Streptococcus, Escherichia coli, and Listeria monocytogenes best represents the most common etiologies of meningitis in neonates.