Bacillus species are Gram-positive, aerobic, ubiquitous bacteria characterized by their ability to form resistant spore coats. About 48 known species exist in the genus Bacillus but only B. anthracis and B. cereus are associated with human disease. Bacillus species produce heat-resistant endosopores and have a growth range of 10°C to 48°C, with optimal growth at 28°C to 35°C. They can grow in a broad pH range of 4.9 to 9.3.
Bacillus anthracis causes the disease Anthrax in humans and animals via direct contact with infected carriers or by inhalation of spores. In rare instances, consumption of contaminated meats has led to foodborne illnesses associated with B. anthracis. Conversely, B. cereus causes the majority of foodborne illnesses attributed to Bacillus. Although the incidence of naturally acquired anthrax is extremely rare in the United States, the Centers for Disease Control and Prevention estimated that in the year 2001, 22 cases occurred. From 1993 to 1997, B. cereus was linked to 14 outbreaks and caused 691 reported cases of foodborne illness in the United States.
Because of recent acts of terrorism and the threats of bioterrorism, B. anthracis remains an organism for which control mechanisms are necessary. While the most efficient method of delivering this biological weapon would be via an airborne route, the contamination of foodstuffs and water sources is possible. With the Public Health Security and Bioterrorism Preparedness and Response Act of 2002 and as the government continually prepares and responds to the threat of bioterrorism, clinical microbiological laboratories could play key roles in the detection, identification, and control of B. anthracis.