Let me share with you a comparison between Gram positive and Gram negative bacteria.
| Aspect | Gram-Positive Bacteria | Gram-Negative Bacteria |
| Chemical makeup of cell wall | The cell wall is primarily composed of a thick layer of peptidoglycan. | The cell wall contains a thin layer of peptidoglycan surrounded by an outer membrane. |
| Outer Membrane | Absent | Present |
| Plasma Membrane | Contains a plasma membrane just beneath the cell wall | Contains a plasma membrane beneath the thin peptidoglycan layer and an outer membrane |
| Periplasmic Space | Smaller or absent periplasmic space | Larger periplasmic space |
| Lipopolysaccharides (LPS) | Absent | Present in the outer membrane, including lipopolysaccharides (LPS) |
| Staining Reaction | Retains the crystal violet stain during Gram staining, appearing purple under the microscope. | Takes up the counterstain (safranin or fuchsin) during Gram staining, appearing pink under the microscope. |
| Teichoic Acids | Present (lipoteichoic and wall teichoic acids) | Absent or minimal presence |
| Susceptibility to Antibiotics | Generally more susceptible to antibiotics | Often more resistant to antibiotics |
| Porins | Fewer porins in the cell wall | Abundant porins in the outer membrane |
| Exotoxins and Endotoxins | Often produces exotoxins | May produce both exotoxins and endotoxins |
| Resistance to Environmental Stress | Generally more resistant to environmental stress | More susceptible to environmental stress |
| Examples | · Staphylococcus
· Streptococcus · Bacillus |
· Escherichia
· Salmonella · Pseudomonas · Neisseria |
| Common Infections | · Skin infections
· Some gastrointestinal infections |
· Gastrointestinal infections
· Respiratory infections · urinary tract infections · sepsis |