What it means
With a capital B and in italics in print, Bacillus is a genus (group) of bacteria that make hardy spores, such as Bacillus anthracis (anthrax) and Bacillus cereus (a cause of food poisoning). In lowercase, "bacillus" (plural bacilli) describes the rod shape of any bacterium; for example, tuberculosis is caused by an acid-fast bacillus.
At a glance
| Also written | bacilli |
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Related terms
bacterium
A tiny one-celled living thing, seen only under a microscope, of which some kinds cause disease; the plural is bacteria.
tuberculosis
An infection caused by the bacterium Mycobacterium tuberculosis, which most often attacks the lungs.
spore
A tough, resting form that some bacteria and fungi make, able to survive heat, drying and many cleaning products.