AEROSOLS AS A SOURCE OF WIDESPREAD MYCOPLASMA CONTAMINATION OF TISSUE CULTURES.

Mycoplasma isolates were cultured from 15 antibiotic-free cell cultures obtained from a single laboratory. Complement-fixation tests showed that these isolates were antigenically related to each other but were unrelated to M. hominis type 1, M. hominis type 2, M. arthritidis, M. laidlawii type B, Mycoplasma sp. H.Ep. #2 (Barile), or M. salivarium. Examination of serum used to feed the infected cell lines revealed no Mycoplasma. Infection resulting from cross-contamination by a single Mycoplasma strain from one cell culture to another was investigated. Although the organisms were not found in the air over the work area, aerosols containing these contaminants were produced in tissue culture bottles during the trypsinization of cell monolayers. The minimal infectious dose of Mycoplasma for tissue cultures was measured, and it was determined that one organism was capable of initiating an infection in a tissue culture. The pattern of contamination and the small dose required for infection indicated that Mycoplasma contamination was spread from one tissue culture to another via aerosols. It was demonstrated that Mycoplasma can be transferred from one cell culture to another through the use of a common burette for dispensing medium.