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Chapter 100 : Isolation of Legionella and Amoebae from Water Samples
Many studies describe Legionella's ability to survive and to multiply in about 30 species of amoebae, especially Acanthamoeba, Naegleria, and Hartmanella, and in two species of ciliates. This chapter describes isolation of Legionella from hospital water supplies and from air conditioning systems during periodic controls sometimes performed after water disinfection. The culture of amoebae was also performed, and the interactions with legionellae were studied. Legionella was isolated from 251 of 471 (53.3%) hospital water samples (239 hot and 12 cold), corresponding to 11 of 12 (91.7%) hospitals. Amoebae alone were isolated from 27 of 471 (5.7%) samples, while Legionella alone were isolated from 196 of 471 (41.6%) samples. The distribution of Legionella and amoebae in all water samples in relation to temperature have been discussed in the chapter. The results of this study confirmed those observed by other authors reporting similar data for Legionella isolation (55%). In conclusion, the Legionella isolation rate was higher than that of amoebae from hospital water supplies, but amoebae were found in higher percents from air conditioning systems (64%, the despite limited number of samples examined) where Legionella was absent.