Streptococcus pneumoniae

Streptococcus pneumoniae

Virulence factors:

– Its polysaccharide capsule inhibits phagocytosis, and recombination of capsular genes facilitates antibiotic resistance. – Surface proteins bind respiratory tract epithelia, which facilitates respiratory infections. – IgA protease keeps the bacteria trapped within the mucin and inhibits clearance. – Pneumolysin lyses phagocytic cells and ciliated respiratory epithelium, which also prevents bacterial clearance. – Complement activation produces inflammation, and is triggered by pneumolysin, teichoic acid, and peptidoglycan fragments.

Hydrogen peroxide damages host tissues.
Phosphorylcholine facilitates entry into host cells, which protects bacteria from removal and promotes migration to deeper tissues.

Infectious Diseases

– Pneumonia, particularly in the lower lobes: In the sample, we can see that bacteria, red blood cells, and white blood cells infiltrate the alveolar tissue. Symptoms include chest pain (aka, pleurisy) with fever and chills with coughing that produces rust-colored sputum. Be aware that patients with dysfunctional or absent spleens can have severe forms of pneumococcal pneumonia. – Otitis media and sinusitis can occur after viral infections that obstruct sinus drainage and allow bacteria to proliferate. – Pneumococcal meningitis can occur when Streptococcus pneumoniae spreads to the central nervous system. This can happen as a result of bacteremia or when trauma produces a connection between the nasopharynx and subarachnoid space.

References

Streptococcal meningitis (CDC/ Dr. Edwin P. Ewing, Jr.).

Streptococcus pneumoniae

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