TISSUE CELL CULTURE CONTAMINATION IN RELATION TO BACTERIAL PLEUROPNEUMONIA-LIKE ORGANISMS-L FORM CONVERSION

Abstract

This paper describes the experimental induction in tissue culture of an L phase variant from a gram-negative bacillary contaminant of a tissue cell culture (NCTC clone 929, mouse fibroblast) when treated with 15 to 25 units per ml. of polymyxin B, and the subsequent reversion of the induced stable L form to the original bacterial form by withdrawal of the antibiotic. In laboratory medium, the cloned L phase variant required both horse serum and 1% yeast extract in Difco heart infusion broth to revert to the bacterial form. The L form was readily induced when certain concentrations of polymyxin B were added to the heart infusion serum broth inoculated with the bacterial form. The results support the hypothesis that the source of infections from pleuropneumonialike organisms (PPLO) in tissue cells is the conversion of bacterial contaminants to stable L forms by antibiotics commonly used to prevent bacterial contamination.