Prevention or elimination of mycoplasma contamination of a culture of animals or plant cells.

A method for preventing or eliminating pollution of microplasma cultured plant cells or animals which comprises addition of an anti-MICROPLASMALMENTE effective amount of 5 - AMINO - 7 - (2 AMINOMETILMORFOLINO) - 1 - CYCLE PROPYL - 6, 8 - difluoro - 1, 4, DIHYDRO - 4 - oxoquinoline - 3 - carboxylic acid or its salt to a half-eDUCATED IN wHOSE animal or plant cells are grown, AND AN AGENT OR PREPARING TO PREVENT OR ELIMINATE POLLUTION microplasma CELLS cultured OF ANIMAL OR PLANT COMPRISING 5 - AMINO - 7 - (2 AMINOMETILMORFOLINO) - 1 - cyclopropyl - 6, 8 - difluoro - 1, 4 - DIHYDRO - 4 - oxoquinoline - 3 - CARBOXYLIC or salts thereof.