Role of cell-associated pathogen metabolism in infection of tracheal explants by Mycoplasma pneumoniae.

The effect of environmental conditions on the relative pathogenicity of Mycoplasma pneumoniae for hamster tracheal explants was investigated. Organisms from the early stages of the growth cycle (e.g., day 1 to 2) were more effective in the induction of ciliostasis than were older cultures. Both the degree of ciliostasis and the speed of onset were affected. The type of explant culture medium also affected pathogenic potential. M. pneumoniae infection produced significantly greater ciliostasis and cytonecrosis in a "permissive" medium, i.e., one capable of supporting mycoplasma metabolism and replication, than in a "nonpermissive" medium. However, no adenine protection effect could be detected under permissive conditions, though it was quite striking when a nonpermissive medium was used as the post-infection explant medium. This suggests that the cell damage noted under permissive conditions may result from processes distinct from those operative in the actual host-parasite cellular interaction.