Effects of exposure to peroxyacetyl nitrate on susceptibility to acute and chronic bacterial infection

A significant increase in mortality due to acute respiratory pneumonia caused by inhalation of Streptococcus pyogenes aerosol was seen after a single 3-h exposure of mice to 14.8-28.4 mg/m3 peroxyacetyl nitrate (PAN). The excess mortality ranged from 8 to 39% and the decrease in survival time from 2.4 to 7.9 d. A single exposure to 25.0 mg/m3 PAN resulted in a significant increase in total number of cells lavaged from the lungs but somewhat decreased levels of adenosine triphosphate (ATP) in alveolar macrophages. Exposure to 7.4 mg/m3 PAN for 3 h/d, 5 d/wk, for 2 wk resulted in a reduced total count of free pulmonary cells and a significant reduction of ATP levels in alveolar macrophages but had no effect on mortality or survival rate. Scanning electron microscopic observations of the respiratory tract after both single and multiple exposures to PAN showed raised and sloughing nonciliated cells in the nasal cavities and tracheas and presence of excess mucus. Six daily 3-h exposures to 25.0 mg/m3 PAN did not produce any marked changes in a chronic respiratory infection in mice as measured by Mycobacterium tuberculosis lung titers.