Isolation and Elimination of Pleuropneumonia-Like Organisms From Mammalian Cell Cultures. ∗

Abstract

Summary

One hundred sixty-six sublines representative of 68 culture lines of cells of human, rabbit, monkey, mouse, pig, cow and other species origin were tested repeatedly for contamination with pleuropneumonia-like organisms over a period of 18 months. Cells freshly dispersed with trypsin were inoculated into a medium containing pancreatic digest of beef heart enriched with yeast extract and human ascitic fluid. Of the tested sublines, 57% were contaminated with PPLO. Repeated tests with the heart digest medium on 89 sublines were consistently positive, while 5 sublines yielded variable results. PPLO strains isolated from 2 of the variable cell sublines grew sparsely and slowly, but growth of other PPLO strains was luxuriant in the test medium. Fifteen cell lines carrying PPLO of varying colonial morphology were treated for 3 weeks with 100 μg of kanamycin per ml of medium. Treated sublines yielded no PPLO during subsequent cultivation for nearly a year in the absence of kanamycin. A contaminated strain of human esophageal epithelium has been freed of PPLO by brief exposure to kanamycin. Required time of exposure appeared inversely related to kanamycin concentration employed.