In the group that received ciprofloxacin but no vaccine, only four of nine monkeys, or 44 percent, survived the challenge. The animals remained healthy while on antibiotics but succumbed when the antibiotics were discontinued after 14 days. In contrast, all 10 monkeys that received 14 days of antibiotics plus vaccination survived when the antibiotics were discontinued. Thus, postexposure vaccination enhanced the protection afforded by 14 days of antibiotic prophylaxis alone, and completely protected all the animals against inhalational anthrax.
"This provides direct evidence that the combination of anthrax vaccine with a short course of antibiotics given postexposure can completely protect nonhuman primates from inhalational anthrax," said senior author Arthur M. Friedlander, M.D., of USAMRIID. "Our results also suggest that the appearance of an antibody response--after treatment with antibiotics alone or in conjunction with vaccination--might be useful in determining when antibiotics can be safely discontinued."
According to Friedlander, inhalational anthrax begins when anthrax spores are ingested into the deep recesses of the lung. When the spores germinate, they are transformed into vegetative cells that produce three components contributing to virulence--lethal toxin, edema toxin, and capsule. The capsule surrounds the vegetative cell and prevents it from being ingested by host white blood cells that would otherwise destroy it, thus allowing anthrax infection to progress. The toxins are thought to act mainly by damaging defensive cells called phagocytes, causing the immune system to malfunction. The organism then spreads unimpeded to all major organs of the body, causing tissue damage and death.
While most spores probably germinate wit
Source:US Army Medical Research Institute of Infectious Diseases