Q.76 Which of the following infectious agents cross the blood-brain barrier?
(P) Streptococcus pneumoniae
(Q) Coxsackie virus
(R) Rotavirus
(S) Streptococcus pyogenes
(A) P & S
(B) R & S
(C) P & Q
(D) Q & R
Streptococcus pneumoniae and Coxsackie virus can cross the blood-brain barrier, making option (C) P & Q the correct choice. This multiple-choice question tests knowledge of microbial pathogens capable of CNS invasion.
Correct Answer
(C) P & Q
Streptococcus pneumoniae (P) and Coxsackie virus (Q) breach the blood-brain barrier (BBB), unlike rotavirus (R) or Streptococcus pyogenes (S).
Option Breakdown
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(P) Streptococcus pneumoniae: This bacterium causes bacterial meningitis by directly traversing the BBB, often via endothelial cell invasion or “Trojan horse” mechanism in infected leukocytes. Pneumococcal meningitis remains a leading CNS infection globally.
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(Q) Coxsackie virus: Enterovirus like Coxsackie B strains infect brain endothelial cells, disrupting tight junctions to cross the BBB and cause aseptic meningitis or encephalitis. Studies confirm its CNS entry via bloodstream.
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(R) Rotavirus: Primarily causes gastroenteritis; lacks neurotropism and does not cross the BBB effectively. No association with meningitis reported.
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(S) Streptococcus pyogenes: Causes pharyngitis and skin infections but rarely invades the CNS directly. BBB crossing uncommon; neurological issues typically secondary.
Clinical Relevance
Pathogens breaching the BBB trigger meningitis or encephalitis, demanding rapid diagnostics like CSF analysis. Vaccines prevent pneumococcal cases, while Coxsackie infections rely on supportive care. Understanding these mechanisms aids in microbiology exam prep and research.
