Anthrax bacteria in lung. Coloured scanning electron micrograph (SEM) of a cluster of anthrax bacteria (Bacillus anthracis) in a capillary of the lung. These rod-shaped, Gram-positive bacteria are highly pathogenic. Commonly an infection of livestock, B. anthracis is transmitted to humans by contact with contaminated animal hair, hides or excrement. Two forms of the disease occur: pneumonia in the lungs (woolsorter's disease), and cutaneous anthrax, which causes a large boil at the site of the bacteria's entry. Antibiotic treatment, if prompt, may be effective for the skin infection. Pulmonary anthrax is fatal in most cases. Magnification: x540 at 6x7cm size. x1750 at 7.5x9.5"~LANDSCAPE"