(bă-sil′ŭs)

[L. bacillus, diminutive of baculum, a staff, walking stick]
A genus of gram-positive, spore-forming, often aerobic, rod-shaped bacteria in the family Bacillaceae. The bacteria grow singly or in chains. Most inhabit soil and water. Some, such as B. anthracis and B. cereus, cause serious human diseases.
SEE: bacterium

Bacillus anthracis

A species that is the causative agent of anthrax. It is one of two bacteria that produces a protein capsule and the only pathogenic bacterium to have the edema factor. (The other bacterium that produces a protein capsule is Yersinia pestis.)
SEE: anthrax toxin; SEE: edema factor; SEE: Yersinia pestis

Bacillus cereus

A species that causes two types of food poisoning syndromes: emesis and diarrhea. Type 1, the emetic syndrome, is caused by the production of a heat-stable cereulide (a small, heat-stable dodecadepsipeptide), which can damage the host cell mitochondria and in rare cases cause liver damage. Foods containing large amounts of rice are more likely to cause the type 1 syndrome. The emetic toxin may not be destroyed by brief cooking. Type 2, the diarrheal syndrome, is caused by production of the heat-labile enterotoxins hemolysin BL and nonhemolytic enterotoxin. These enterotoxins stimulate the adenylate cyclase-cyclic adenosine monophosphate system in intestinal epithelial cells, leading to profuse watery diarrhea. Foods commonly associated with type 2 syndrome are meat and vegetables.
SEE: heat-labile enterotoxin; SEE: heat-stable enterotoxin

Bacillus stearothermophilus

A species that may survive disinfection or sterilization. Its presence on a clinical instrument or surface is an indicator of inadequate sterility.