Contaminations of cell cultures with Mycoplasma are well known phenomena. The types most commonly found are: Myeoplasma orale-I and M. hominis (human); M. hyorhinis (pig) and M. arginini (bovine). Occasionally Acholeplasma laidlawii (bovine) and M. salivarium (human) are detected.
Mycoplasmas are cytopathogenic for primary cells and diploid cell cultures. In cell lines a Mycoplasma contamination often has no pathogenic effect. However, when these cell lines are used in virus research, unreliable results may be obtained.
Bovine types are probably introduced into cell cultures via contaminated calf serum. Barile and Kern (1971) isolated M. arginini from 19~ of calf serum samples. He also found A. laidlawii in a few sera. Contamination of calf serum can be attributed to the method of harvesting of the blood. Usually in our Institute, blood for calf serum is collected aseptically by venous puncture from live calfs. Mycoplasmas were not isolated from 180 such sera. However, for 30 other sera, blood was harvested without aseptic precaution, by cutting through the neck vein (Vena jugularis) of dead calfs. Two such sera were found to be contaminated by M. arginini and A. laidlawii respectively.
We found that for isolation from cell cultures, fresh ox heart broth with boiled sheep blood, inactivated horse serum and yeast extract produces better results than Difco P.P.L.O.-medium with non-inactivated horse serum and yeast extract. Furthermore cell cultures should not be tested immediately after trypsinisation.
Many investigators have tried to eliminate Mycoplasmas from cell cultures, by means of either antibiotics or with antisera. At the moment treating with antisera is preferable. It is evident from literature that treatment with antibiotics is often unsuccessful due to cytopathogenic Table 1. Sensitivity of Mycoplasmatales to various antibiotics, Minimal inhibitory concentration (M.I.C.