Experience with testing for mycoplasma with five different methods.

Five methods for mycoplasma-content detection in cell-cultures are established in this laboratory. Results with about 20 different cell lines continuously grown in this laboratory in some determinations indicate that four methods give good correspondence. A microbiological method gave contrary results in many cases. It is possible that new infections will grow on mycoplasma broth but the older infections are adapted to cell-culture and give negative results on artificial medium. New low-level infections cannot be detected by the other methods which do not include any efficient enrichment step. The most convenient method in our opinion is a DNA-staining method according to Chen because this is a very quick, inexpensive and easily performable process. In practice it seems necessary to check cell cultures in two ways, firstly with a quick method and additionally with the microbiological test to ensure the detection of new low-level infections.