Amoeba-Resistant Microbe Facts :
Studies have confirmed that free-living amoebae are necessary for Legionella multiplication in water biofilm, although they may survive in a latent state in biofilm without amoebae(4)
Microbes that are engulfed by amoebae are encased in internal structures called vesicles. A single vesicle inside an amoeba may harbor thousands of Legionella bacteria(5,6).
When an amoeba containing L. pneumophila encysts to protect itself from adverse environmental conditions, it may protect L. pneumophila from the effects of chlorine(7).
The survival of Mycobacterium avium within amoeba cysts has been well documented(8,9).
Contamination of intensive care unit tap water led to a cryptic epidemic of ventilatoracquired pneumonia caused by L. anisa(10).
Amoeba-Resistant Microbes and Point-Of-Use Filtration :
Free-living Acanthamoeba spp. measure 15-45 microns in diameter, while their cysts measure 10-25 microns in diameter(11). They and the Amoeba-resistant microbes that they might harbor are therefore easily retained by point-of-use 0.2 micron filters.
Some waterborne amoeba-resistant microorganisms include the following :
Legionella pneumophila
Other Legionella spp.
Pseudomonas aeruginosa
Burkholderia cepacia
Burkholderia pseudomallei
Mycobacterium avium
Mycobacterium fortuitum
Mycobacterium simiae
Flavobacterium spp.