Bacterium
The correct term for a single bacterial cell is "bacterium."
Terminology Clarification
The word "bacteria" is plural and refers to multiple bacterial cells, while "bacterium" is the singular form referring to a single bacterial cell. This distinction is important in medical and microbiological communication.
The term "bacteria" was originally created by biologist Christian G. Ehrenberg to describe a single bacterial genus, but eventually became the formal denomination for the entire bacterial group 1. In modern usage:
- Bacterium = singular (one bacterial cell)
- Bacteria = plural (multiple bacterial cells)
Clinical Context
When discussing susceptibility testing and clinical microbiology, the guidelines consistently refer to "a bacterium" when describing individual organisms and their characteristics 2. For example:
- "A bacterium resistant to penicillin..." 2
- "A bacterium is classified as being of intermediate susceptibility..." 2
This singular/plural distinction matters in clinical documentation, laboratory reporting, and scientific communication to maintain precision and clarity.