Neonatal meningitis caused by E. coli is most commonly associated with which capsular polysaccharide serotype, whose structure resembles neural cell adhesion molecule (NCAM) antigens and facilitates blood-brain barrier penetration?
- A K2
- B K1 ✓
- C K5
- D K12
Correct answer: B. K1
Explanation
E. coli K1 is responsible for approximately 80% of neonatal meningitis cases. The K1 capsular polysaccharide is a homopolymeric sialic acid (alpha2-8-linked) that is immunologically identical to the polysialic acid of NCAM on neural tissue, enabling immune evasion and blood-brain barrier penetration. K2 and K5 are associated with UTIs and sepsis but rarely meningitis. K12 is a laboratory strain.
Reference: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.