Health Dictionary
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Bacilli
Introduction
Word Ambiguity
Word Ambiguity
This type of bacteria is shaped like a rod. Usually bacteria separate but sometimes they will stick together. This bacteria can cause tuberculosis in humans.
This article refers to Bacilli in the sense of the class that includes the genus Bacillus..
Although Bacillus, capitalized and italicized, specifically refers to the genus, the word ‘bacillus’ may also be used to describe any single rod-shaped bacterium, and in this sense, bacilli are found in many different taxonomic groups of bacteria.
Likewise, Bacilli refers to the particular class Bacillus belongs to, while bacilli are any rod-shaped bacteria.
It should be noted that the cell morphology term bacillus does not necessarily indicate Gram-positive staining, as E. coli is a Gram-negative, rod-shaped bacteria.
The Class Bacilli
The Class Bacilli
Taxonomically, the term Bacilli refers to a class of bacteria of the division (phylem) Firmicutes. It includes the orders Bacillales and Lactobacillales, and lower down the taxonomic tree includes the genus Bacillus, along with other Gram-positive bacteria such as Listeria.