Metabolic consequences of Mycoplasma pneumoniae infection.

Mycoplasma pneumoniae is a human respiratory pathogen with the ability to infect a wide variety of cell types. Most studies on the nature of metabolic consequences of infection have used cell culture and explant models. Lung fibroblast monolayer cell cultures and rodent tracheal explant cultures have both served as host cells for M. pneumoniae and display metabolic and morphological alterations post infection. Tracheal explants exhibit a decrease in ciliary motion and desquamation, along with a generalized shutdown of major metabolic pathways. Oxygen uptake, dehydrogenase activity, and ATP content all decrease significantly, though 24 to 96 h may be required for detection. Metabolism is affected more rapidly in homogeneous fibroblast monolayers. In those cells, a significant decrease in de novo purine synthesis occurs within 4 h, whereas other pathways, such as salvage DNA synthesis and RNA synthesis had an increased activity. The molecular signals that mediate these changes remain to be delineated, although the inventory of metabolic changes provides a critical step in this process.