Intrabronchial Instillation of Streptococcus pneumoniae in Immunocompetent Rodent Models

Obtain a sterile intubation device consisting of a metal cannula with polyethylene tubing connected to a metal needle.

Attach a syringe containing Streptococcus pneumoniae to the needle, and fill the tubing.

Next, position an anesthetized immunocompetent rat in a supine position.

Insert the free end of the metal cannula into the rat's mouth. Advance it into the trachea toward the left bronchus and down the left lung to an appropriate depth.

Advance the tubing to the end of the cannula and instill the bacterial suspension into the left lung lobe.

The bacterial capsule and surface-associated enzymes prevent bacterial entrapment in the mucus. Further, Streptococcus pneumoniae attach to the surface receptors on bronchial epithelial cells, facilitating endocytosis and release to the basolateral surface. 

Bacteria secrete toxins that damage the epithelial cells and barriers, triggering an immune response.

However, Streptococcus pneumoniae has developed strategies to evade the host immune response and establish lung infection.