EXPERIENCES WITH IMPROVED METHODS FOR THE DETECTION OF LEGIONELLAE INDRINKING-WATER

Entry of Legionellae into domestic water systems by passing through th e drinking water distribution network has been assumed. To prove this question, samples were collected within a two years period at warm and cold water taps of households, the pipeline network and three water w orks of the city of Mainz, and examined for the presence of Legionella e. To detect even very small numbers of Legionellae, improvement of th e conventional isolation procedure was necessary. Additionally, large volumes of cold water samples (50-250 L) were processed by using a pre ssure filter. For identification of Legionellae, an immunological rapi d test (colony-blot-assay, own development) and a commercial gene-prob e test (EnvironAmp(TM) Legionella Kits, Applied Biosystems) were enclo sed in the programm. With the refined techniques the detection limit w as improved while expenses of time and labour were reduced. Finally, t he advantages and disadvantages of the single methods are discussed. F or routine detection of Legionellae in the microbiological laboratory, a combination of effective methods is proposed which are easy to perf orm.