THE PASSAGE OF RABBIT VIRULENT TYPE III PNEUMOCOCCI FROM THE RESPIRATORY TRACT OF RABBITS INTO THE LYMPHATICS AND...

Area of Science:

• Bacteriology
• Immunology
• Pathogenesis

Background:

• Streptococcus pneumoniae, particularly virulent Type III strains, can cause severe respiratory infections.
• Understanding the initial host-pathogen interactions and lymphatic spread is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the early lymphatic dissemination of rabbit virulent Type III pneumococci following intranasal or intratracheal inoculation.
• To evaluate the efficacy of early intravenous antiserum administration in preventing bacterial spread.

Main Methods:

• Rabbit virulent Type III pneumococci were instilled into the nasal or tracheal passages of rabbits.
• Lymph and blood samples were collected over a 4-hour period to detect bacterial presence.
• Intravenous antiserum was administered 2.5 to 3 hours prior to bacterial instillation in a subset of animals.

Main Results:

• Pneumococci were consistently recovered from draining lymphatics within 1-4 hours post-instillation, often detectable by the first hour.
• Bacterial presence was predominantly observed first in lymphatics, with subsequent, less frequent, recovery from the blood.
• Pre-treatment with antiserum significantly reduced the number of animals with positive lymph or blood cultures and the duration of bacterial recovery in lymph.

Conclusions:

• Virulent Type III pneumococci rapidly disseminate via lymphatics from the initial site of respiratory tract infection.
• Early administration of specific antiserum can effectively limit pneumococcal spread to lymphatics and bloodstream, indicating a critical window for therapeutic intervention.