18 - Bacillus

Abstract

Members of the genus Bacillus are large, aerobic, gram-positive, and sporeforming rods. They are catalase positive; many are fermentative and most are motile. Bacillus species occur widely in nature, being found in the air, water, and soil. They are among the most common laboratory contaminants and are usually ignored when recovered from clinical materials. More than 40 species of Bacillus have been identified. This chapter discusses the more common and important species of Bacillus. They are Bacillus anthracis, Bacillus cereus, and Bacillus licheniformis. Anthrax is most frequently seen in cattle, in which it usually causes an acute septicemic infection. The numbers affected depend upon the source of Bacillus anthracis. The chapter reviews the pathogenicity, laboratory diagnosis, isolation procedures, and methods of identification of Bacillus anthracis. Bacillus cereus is a widespread saprophyte that is capable of infecting the bovine udder and producing acute and sometimes fatal gangrenous mastitis. It is a cause of abortion in cows and ewes.. The Bacillus species that have been implicated in human infections are Bacillus cereus, Bacillus circulans, Bacillus coagulans, Bacillus brevis, Bacillus pumulus, Bacillus macerans, Bacillus subtilis, Bacillus sphaericus, and Bacillus thuringiensis.