Which statement accurately describes Escherichia coli strains associated with neonatal meningitis?

Which statement accurately describes Escherichia coli strains associated with neonatal meningitis?

• A. They are non-encapsulated.
• B. They lack fimbriae.
• C. They do not cause meningitis.
• D. They are encapsulated with a K1 antigen.

Answer: (D)

Neonatal meningitis–associated E. coli are defined by carrying a polysaccharide capsule of the K1 type. This capsule is a powerful virulence factor because it is antiphagocytic and helps the bacteria survive in the bloodstream and cross into the central nervous system, leading to meningitis in newborns. The K1 capsule also resembles host polysialic acid, which helps the bacteria evade immune detection. Non-encapsulated strains are less capable of causing meningitis, and these particular bacteria do cause meningitis in neonates, so statements claiming they do not would be inaccurate. Fimbriae can contribute to adhesion in many E. coli infections, but their presence or absence is not the defining trait of strains that cause neonatal meningitis; the K1 capsule is the key feature that links these strains to meningitis in newborns.

Neonatal meningitis–associated E. coli are defined by carrying a polysaccharide capsule of the K1 type. This capsule is a powerful virulence factor because it is antiphagocytic and helps the bacteria survive in the bloodstream and cross into the central nervous system, leading to meningitis in newborns. The K1 capsule also resembles host polysialic acid, which helps the bacteria evade immune detection.

Non-encapsulated strains are less capable of causing meningitis, and these particular bacteria do cause meningitis in neonates, so statements claiming they do not would be inaccurate. Fimbriae can contribute to adhesion in many E. coli infections, but their presence or absence is not the defining trait of strains that cause neonatal meningitis; the K1 capsule is the key feature that links these strains to meningitis in newborns.