<prompt> Which of the following is true regarding anthrax ?M Fadyean reaction shows capsuleHumans are usually resistant to infectionLess than 100 spores can cause pulmonary infectionAll  <response>: Ans. is a i.e., M Fadyean reaction shows capsule; b i.e., Humans are usually resistant to infection; c i.e., Less than 100 spores can cause pulmonary infection . M Fadyeans reaction represents the capsular material and is characteristic of the anthrax bacillus. . Man is relatively resistant to infection with B. anthracis. - Green wood 16the 226 . In animal studies, it has been shown that aerosolized anthrax -- 10,000 spores required to produce lethal disease. However, it has been suggested that as few as one to three spores may be adequate to cause disease in some setting. - Harrison 17thie 1344 . Spores are of same width as the bacillary body so that they do not cause bulging of the vegetative cell in contrast the clostridia have bulging spores. . For laboratory diagnosis, specimens to be examined are fluid or pus from a local lesion, blood or sputum. Stained smears often show chains of large gram positive rods. 