What are the three basic shapes of pathogenic bacteria?

The three basic shapes of pathogenic bacteria are coccus, bacillus, and spirillum.

Coccus refers to spherical-shaped bacteria, which can exist as single cells or form clusters. Bacillus describes rod-shaped bacteria, which can also vary in arrangement, such as being single or forming chains. Spirillum refers to bacteria that have a spiral or corkscrew shape, which assists in their mobility in various environments.

Understanding these shapes is essential in microbiology and pathology because the shape can influence how bacteria function, their reproduction methods, and the types of infections they may cause. Additionally, identifying the shape is a fundamental step in differentiating between types of bacteria during laboratory tests and diagnostics.

The other options mentioned do not accurately represent the recognized shapes of pathogenic bacteria in the scientific community, making option A the correct choice.