Viability and ultrastructural changes in group E Streptococci after in vitro phagocytosis by swine macrophages.

The loss of viability and ultrastructural changes were studied in group E Streptococci (GES) after in vitro phagocytosis in immune swine macrophages. There was a 50% reduction in the viability of intracellular GES during the first 60 minutes of incubation and a total loss of viability by 300 minutes as compared to the control tubes where the GES increased. Loss of viability in phagocytized group E Streptococci was associated with the appearance of degenerative changes in the bacterial cytoplasm. This was followed by disruption of the bacterial cell membrane and its separation from the bacterial cell wall. No definite evidence of cell wall degeneration could be found. Unphagocytized organisms incubated for similar periods and fixed in the same manner did not lose viability nor have any degenerative changes.