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Rocz Panstw Zakl Hig 2000, 51(2): 183-190

Wykrywanie i izolacja bakterii z rodzaju Legionella ze środowiska wodnego
[Detection and isolation of Legionella from water environment]

R. Matuszewska , В. Krogulska

ABSTRACT

The aim of this work was to find method of isolation of bacteria of genus Legionella from water evironment. Were used reference strains such as: L. pneumophila ATCC 33152, strains of bacteria contaminated water samples: E. coli ATCC 35218, S. aureus ATCC 12600, Str. faecalis ATCC 29212 and P. aeruginosa - strain from own colection, isolated from water environment. Because of the slow growth of bacteria of genus Legionella and dangers of contamination the preliminary treatment of examined water samples should be done. Water samples inoculated with standard strains of bacteria before inoculation by plated membrane filtration or plated directly methods were undergone acid pretreatment (acid buffer pH 2,2) and heat pretreatment (temp. 50°C). The contact time used for studies was respectlively 10,20,30 min. and 30, 45 min. The best time used for acid treatment procedure was 10 min. , for heat treatment procedure was 30 min. Such adjust parameters of preliminary treatment of water samples should reduce enough growth of non-Legionella organisms and not to influence the growth of searched Legionella strains. The researches showed that the most succesfull of isolation is membrane filtration method, where filters are directly placed on the culture medium. In studies buffered charcoal yeast extract agar medium with cysteine, activated charcoal and selective suplements were used. The growth of bacteria on the cellulose, polycarbonate and polyvinylidene fluoride filters were compared. The best results were achieved with cellulose and polyvinylidene fluoride filters. Growth of colonies of bacteria on the filters should be examinated between 3rd and 7th days of incubation period at 37°C and 90% relative humidity. Legionella forming colonies growing on membrane filters are shining with smooth edge, cream or white. On the polyvinylidene fluoride filters around colonies clear zones are observed.

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