Susceptibility of irradiated mice to Bacillus anthracis sterne by the intratracheal route of infection.
The susceptibility of sublethally irradiated mice to pulmonary infection with Bacillus anthracis was investigated in a mouse model. Female B6D2F1/J mice were challenged intratracheally with 4.3 x 10(6), 3.7 x 10(7) and 4.4 x 10(8) cfu of B. anthracis Sterne spores 4 days after 60Co gamma-radiation at a dose of 0, 1, 2, 3, 4, 5, 6 or 7 Gy. Bacterial cultures were obtained from lung, spleen homogenates and heart blood. A biphasic mode of mortality was observed, with a constant response of up to 3 or 4 Gy (up to 18% mortality), after which a sharp increase in mortality occurred (up to 100%). When irradiation was delayed beyond 15 days after inoculation, the susceptibility to B. anthracis infection and subsequent mortality disappeared. B. anthracis was recovered from the organs and blood of up to 89% of the animals. However, organisms of enteric origin were also isolated mixed with B. anthracis from up to 36% of the animals exposed to 3, 5 or 7 Gy. Inoculation of B. anthracis delta-Sterne-1 that lacks lethal toxin and oedema toxin also induced infection with B. anthracis, but not translocation of enteric micro-organisms. The synergic adverse effect of exposure to gamma-radiation followed by intratracheal challenge with B. anthracis was observed above 4 Gy. The lethal toxin of B. anthracis may enhance the emergence of polymicrobial infection with B. anthracis and enteric micro-organisms.
Brook
Itzhak
I
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Elliott
Thomas B
TB
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Harding
Rita A
RA
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Bouhaouala
S Samy
SS
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Peacock
Susan J
SJ
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Ledney
G David
GD
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
Knudson
Gregory B
GB
Radiation Medicine Department, Armed Forces Radiobiology Research Institute, 8901 Wisconsin Avenue, Bethesda, MD 20889-5603, USA.
D000818:Animals; D000881:Anthrax / Q000276:immunology* / Q000401:mortality; D001408:Bacillus anthracis / Q000472:pathogenicity*; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004198:Disease Susceptibility; D004487:Edema; D005260:Female; D005720:Gamma Rays; D006321:Heart / Q000382:microbiology*; D008168:Lung / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D013154:Spleen / Q000382:microbiology* / Q000473:pathology; D013171:Spores, Bacterial; D016019:Survival Analysis