The etiologic agent most commonly associated with septicemia and meningitis of newborns is which organism?

• A. Streptococcus agalactiae
• B. Streptococcus bovis group
• C. Streptococcus pneumoniae
• D. Streptococcus pyogenes

Answer: (A)

Neonatal septicemia and meningitis are most commonly caused by Group B Streptococcus, Streptococcus agalactiae. This organism frequently colonizes the maternal genital tract, and transmission to the newborn can occur during labor, leading to early-onset disease within the first week of life. Its ability to invade and multiply in the neonate’s bloodstream and meninges makes it the leading cause of both sepsis and meningitis in this age group. Other streptococci listed are much less commonly implicated in newborn infections: Streptococcus pneumoniae is a major cause of meningitis in adults and older children, not typical for neonates; Streptococcus pyogenes can cause severe neonatal infections but is not the predominant agent; Streptococcus bovis group is more associated with endocarditis and colorectal pathology in adults. Thus, Streptococcus agalactiae best fits as the etiologic agent most commonly linked to septicemia and meningitis of newborns.