RT Journal Article
SR Electronic
T1 <em>Mycobacterium avium</em> Bacilli Grow Saprozoically in Coculture with <em>Acanthamoeba polyphaga</em> and Survive within Cyst Walls
JF Applied and Environmental Microbiology
JO Appl. Environ. Microbiol.
FD American Society for Microbiology
SP 2256
OP 2261
VO 64
IS 6
A1 Steinert, Michael
A1 Birkness, Kristin
A1 White, Elizabeth
A1 Fields, Barry
A1 Quinn, Frederick
YR 1998
UL http://aem.asm.org/content/64/6/2256.abstract
AB Protozoans are gaining recognition as environmental hosts for a variety of waterborne pathogens. We compared the growth ofMycobacterium avium, a human pathogen associated with domestic water supplies, in coculture with the free-living amoebaAcanthamoeba polyphaga with the growth of M. avium when it was separated from amoebae by a 0.1-μm-pore-size polycarbonate membrane (in a parachamber). Although viable mycobacteria were observed within amoebal vacuoles, there was no significant difference between bacterial growth in coculture and bacterial growth in the parachamber. This suggests that M. avium is able to grow saprozoically on products secreted by the amoebae. In contrast,Legionella pneumophila, a well-studied intracellular parasite of amoebae, multiplied only in coculture. A comparison of amoebae infected with L. pneumophila and amoebae infected with M. avium by electron microscopy demonstrated that there were striking differences in the locations of the bacteria within amoebal cysts. While L. pneumophila resided within the cysts, M. avium was found within the outer walls of the double-walled cysts of A. polyphaga. These locations may provide a reservoir for the bacteria when environmental conditions become unfavorable.