Introduction: L.Pneumophila has been known as a facultative intracellular bacterium which could proliferate within mammalian macrophages and a wide spectrum of free-living protozoa such as A. castellianii. Its pathgenicity for both host cell types could be mostly dependent on the intracellular living conditions.
Materials and Methods: L. pneumophila-infected acanthamoeba were examined by a flour rescent microscopy after lysosomal labeling with acridine orange (AO) to determine whether intracellular survival of the bacteria is associated with the failure of legionella containing phagosomes to fuse with the primary lysosomes.
Results L. pneumophila acrively inhibited phagosome-lysosome-fusion and appeared to preferentially divide within unfused phagocytic vesicles. Interestingly, most of the E.coli containing phagosomes can fuse with amoebae lysosomes.
Conclusion: Free-living amoebae usually engulf different ubiquitous bacteria in the environment and ingest them as food particles. Legionaries, disease bacterium however, overcome nasty intra-amoebae phagosomes by inhibition of phago-lysosome. This simply explains how the efforts for legionella eradiation from the water sources have had unsuccessful results