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PURIFICATION OF CONTAMINATED CULTURES

The purification of contaminated cultures can be performed with the following methods:

Filtration

Contaminating bacteria usually do not pass a membrane filter with a pore size of 0.22 um.

FU in media

5-fluoro-uracil (200 microgram per ml medium) does not interfere strongly with leptospiral growth, but suppresses the growth of contaminating bacteria.

Plating

Inoculate ten-fold dilutions of culture ranging from 1:1000 to 1:1,000,000 on solid medium. Growing of leptospires on solid media will take 2-3 weeks and should be done in a humid environment to avoid drying of the medium plates.

Animals

Inject the contaminated culture in a hamster or a guinea pig (intraperitoneally). Take blood by heart-puncture after 10-15 minutes and inoculate the blood in culture medium.