| Autor: |
Stephenson, E. H., Moeller, R. B., York, C. G., Young, H. W. |
| Zdroj: |
American Industrial Hygiene Association Journal; March 1988, Vol. 49 Issue: 3 p128-135, 8p |
| Abstrakt: |
The effectiveness of two aerosol delivery systems, nose-only and whole-body, were compared using Swiss-Webster mice and two pathogens, Klebsiella pneumoniae and Venezuelan equine encephalitis (VEE) virus. With K. pneumoniae the median lethal dose (LD50) and the mean time to death correlated with the inhaled dose. An LD50 value of 335 colony forming units (cfu) for nose-only exposure was significantly less than the LD50 value of 3741 cfu obtained for whole-body exposure. The LD50 values obtained with VEE virus for nose-only exposure [8 plaque forming units (pfu)] and whole-body exposure (11 pfu) were similar to each other. Following a 10-min nose-only exposure, concentrations of K. pneumoniae approximating lO4/g were present after 24 hr in the upper respiratory tract (URT) and lungs. The numbers of bacteria reached a peak at 72 hr, when resolution of the infection began. Detectable levels of bacteria in the blood and tissues were delayed in mice given whole-body exposure, plus there was a decreased concentration of bacteria per gram of tissue. Major pathological lesions induced by K. pneumoniae were mild suppurative rhinitis and minimal suppurative bronchopneumonia. Viremia was greatest at 96 hr following aerosol exposure to VEE. Virus concentrations in the URT, lungs, cerebrum, spleen and mesenteric lymph nodes reached maximum titers earlier for mice exposed by nose-only than for mice exposed to whole-body aerosols. High virus concentrations were associated with necrosis of the lymphoid tissues which was the probable cause of death. Disease induced with VEE virus by both aerosol systems was identical. |
| Databáze: |
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