Streptococcus pneumoniae, an encapsulated bacterium, enters the respiratory tract of a young child for the first time while that child has influenza. The child subsequently develops pneumococcal pneumonia, is treated with antibiotics, and recovers.
1. Normally when bacteria first enter the body, the innate immune defenses bind PAMPs on the bacterial cell wall to endocytic PRRs on the body's phagocytes and the organism is phagocytosed. Explain why the child's innate phagocytic defense was unable to remove the S. pneumoniae.
2. The pneumococcal conjugate vaccine, PCV13 or Prevnar 13® is currently recommended for all children under 5 years of age. Why might prior vaccination with this vaccine have enabled the child to to remove the S. pneumoniae via phagocytosis?