Cooling Towers House New Bacteria-Infecting Amoebas

An amoeba is infected with a novel bacterium, CC99. Numerous coccoid bacteria fill the nucleus of the amoeba 48 hours after infection as it begins to rupture.  Art/Mary Farone 

Results of a new study published online by Environmental Science & Technology suggest these amoebas infected with bacteria are more prevalent in cooling towers than in natural environments. Sharon Berk of Tennessee Technological University and colleagues sampled 40 cooling towers in hospitals, universities and industries and 40 natural environmentslakes, rivers, creeks and pondsfinding infected amoebas in 22 of the cooling towers and only three of the natural samples.

"The bacteria responsible for Legionnaire's disease use amoebas as a host, as do many related bacteria," said Berk, a TTU biology professor.

The bacteria can then hijack the amoeba's cellular machinery and then multiply profusely. According to Berk, eventually the amoeba swells and bursts like a balloon, releasing the bacteria by the hundreds.

People can contract pneumonia after inhaling Legionella in aerosol drifts from cooling towers, according to a related ES&T article. It is possible that other amoeba-associated microorganisms, such as those found in cooling towers in the study, may be unrecognized causes of other respiratory disease.

Source: Tennessee Technological University