Slides containing bacteria are stained with crystal violet and iodine, destained with alcohol, and counterstained with safranin. Under the mircoscope, the bacteria appear a bluish-purple color. Which class of bacteria are on the slide?
Gram-positive bacteria
Helicobacter
Mycobacteria
Gram-negative bacteria
What is the shape of a streptobacillus bacterium?
Rod-shaped
Rigid helix
Round
Non-rigid helix