Light micrograph of the large rodshaped bacteria Bacillus anthracis (gram positive), causative agent of anthrax in farm animals. The disease is transmitted to man by contact with infected animal hair, hides or excrement. The bacilli attack either the lungs, causing pneumonia (woolsorter's disease), or the skin, producing severe ulceration (malignant pustule). Anthrax is treated with antibiotics. In the body the bacteria appear singly or in pairs, but when cultured they grow in long chains. B.anthracis is a spore-producing bacterium; a single spore per bacterium, which germinates into a new organism.