THE OCCURRENCE OF DEGRADED PNEUMOCOCCI IN VIVO

Area of Science:

• Microbiology
• Immunology
• Pathogenesis

Background:

• Pneumococcus exhibits S (virulent) and R (avirulent) forms.
• The transformation between these forms is crucial for understanding pneumococcal disease progression.

Purpose of the Study:

• To investigate the in vivo transformation of virulent S-form Pneumococcus to avirulent R-form.
• To determine if this transformation is a significant factor in pneumococcal infection outcome.

Main Methods:

• Pneumococcus cultures (S-form) were embedded in agar and implanted subcutaneously in guinea pigs and rabbits.
• Bacterial forms were monitored in vivo and in vitro under various conditions, including in immunized and normal animals, and in normal serum.

Main Results:

• Transformation from S to R forms was observed in vivo (guinea pigs, rabbits, horses) and in vitro.
• Complete S to R transformation was not demonstrated before bacterial clearance.
• R forms appeared in vivo independently of specific immune bodies and persisted even when accessible to phagocytes.
• In vitro cultures in normal serum showed minimal variation, suggesting living tissue fluids may provoke changes.

Conclusions:

• While S to R Pneumococcus transformation occurs in vivo, these experiments do not confirm it as a primary mechanism for recovery from infection.
• Unknown factors within living tissues may induce bacterial variation more readily than in vitro conditions.
• The role of R-form phagocytosis in natural infection resolution requires further investigation.