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Helicobacter pylori
Helicobacter pylori
Gram Negativespirilla
Description
H. pylori is a spiral-shaped, gram-negative bacterium that colonizes the stomach lining. It is associated with gastritis, peptic ulcers, and increased risk of stomach cancer. Its unique helical shape and flagella allow it to penetrate the gastric mucosa.
Membrane Composition
Key Properties
Peptidoglycan:2-7 nm (thin)
Lipopolysaccharide:Present
Teichoic Acid:Absent
Outer Membrane:Present
Membrane Components
- •Inner membrane
- •Periplasmic space with thin peptidoglycan
- •Outer membrane with LPS
- •Flagella
Understanding Gram Classification
Gram-negative bacteria do not retain the crystal violet stain due to their thin peptidoglycan layer (2-7 nm) and outer membrane structure. They appear pink/red after counterstaining with safranin.
The cell envelope has a complex structure: an inner membrane, a thin peptidoglycan layer in the periplasmic space, and an outer membrane containing lipopolysaccharides (LPS). This outer membrane provides extra protection against antibiotics and immune responses.