Production of Respirable Vesicles Containing LiveLegionella pneumophila Cells by TwoAcanthamoeba spp

ABSTRACT Two Acanthamoeba species, fed at three temperatures, expelled vesicles containing living Legionella pneumophilacells. Vesicles ranged from 2.1 to 6.4 μm in diameter and theoretically could contain several hundred bacteria. Viable L. pneumophila cells were observed within vesicles which had been exposed to two cooling tower biocides for 24 h. Clusters of bacteria in vesicles were not dispersed by freeze-thawing and sonication. Such vesicles may be agents for the transmission of legionellosis associated with cooling towers, and the risk may be underestimated by plate count methods.

[1]  W. Johnson,et al.  Interaction of Legionella pneumophila with Acanthamoeba castellanii: uptake by coiling phagocytosis and inhibition of phagosome-lysosome fusion , 1996, Infection and immunity.

[2]  R. Bhopal,et al.  Legionnaires' disease: the infective dose paradox , 1993, The Lancet.

[3]  F. Schuster.  8 – Small Amebas and Ameboflagellates , 1979 .

[4]  S. Berk,et al.  Stimulatory effect of cooling tower biocides on amoebae , 1993, Applied and environmental microbiology.

[5]  W. Martin,et al.  Proliferation of Legionella pneumophila as an intracellular parasite of the ciliated protozoan Tetrahymena pyriformis , 1984, Applied and environmental microbiology.

[6]  T. Ezaki,et al.  Factors Stimulating Propagation of Legionellae in Cooling Tower Water , 1992, Applied and environmental microbiology.

[7]  S. Falkow,et al.  Growth of Legionella pneumophila in Acanthamoeba castellanii enhances invasion , 1994, Infection and immunity.

[8]  T. Rowbotham.  Current views on the relationships between amoebae, legionellae and man. , 1986, Israel journal of medical sciences.

[9]  M. R. Brown,et al.  Trojan horses of the microbial world: protozoa and the survival of bacterial pathogens in the environment. , 1994, Microbiology.

[10]  T. Rowbotham,et al.  Preliminary report on the pathogenicity of Legionella pneumophila for freshwater and soil amoebae. , 1980, Journal of clinical pathology.

[11]  Rowbotham Tj,et al.  Current views on the relationships between amoebae, legionellae and man. , 1986 .